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Embryology
Embryology
301
Medical
Graduate
11/19/2011

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Cards

Term
When does fertilization normally occur (how many days after onset of previous menstrual period)?
Definition
14-15 days
Term
How long does fertilization occur prior to delivery?
Definition
38 weeks
Term
What is capacitation and why is it necessary?
Definition
It is the activation of sperm in the ejaculate. Sperm must be capacitated in order to fertilize the ovum
Term
Where does fertilization occur in the female reproductive tract (be specific)
Definition
Ampulla of the uterine (fallopian) tube
Term
T/F: The zygote enters the uterus immediately after fertilization. (If false, why not?)
Definition
F. Size of the zygote prevents it from moving through the isthmus of the uterine (fallopian) tube. This is due to corona radiata cells.
Term
How long after ovulation does fertilization occur?
Definition
Within 12 hours after ovulation
Term
How long is the ovum viable?
Definition
About 24 hours
Term
How long does it take for the fertilized zygote to travel from ampulla to uterus?
Definition
About 3.5 days
Term
At 16-cell stage the embryo is considered to be a (1). Its cells are called (2).
Definition
1. Morula
2. Blastomeres
Term
What are the function of the cortical granules in the ovum to fertilization?
Definition
They are released once sperm membrane fuses with cell membrane of ovum and cause a change in the physical properties of zona pellucida. This prevents polyspermy.
Term
What is the zona reaction?
Definition
The release of cortical granules in the ovum in response to fertilization by a sperm that changes the physical properties of the zona pellucida, thus preventing polyspermy
Term
The blastocyst is composed of an outer layer of cells called (1) that will eventually form the (2) and an inner layer of cells called the (3) that will eventually form the (4). The fluid-filled space between these two layers is called the (5)
Definition
1. Trophoblast
2. Placenta
3. Embryoblast
4. Embryo
5. Blastocoele
Term
T/F: Normal implantation usually occurs when the embryo is at the mature blastocyst stage
Definition
True
Term
T/F: Normal implantation requires contact of cytotrophoblast with uterine epithelium
Definition
True
Term
T/F: Normal implantation usually occurs on or about the 6th day after fertilization
Definition
True
Term
T/F: Normal implantation leads eventually to complete burial of the blastocyst beneath uterine tissues
Definition
True
Term
T/F: Concerning fertilization: immediately after release from the ovary, the ovum is surrounded by a zona pellucida that must be shed before a sperm can contact the ovum.
Definition
False. The zona pellucida is an essential barrier to polyspermy and is not shed until 5 days post-fertilization.
Term
T/F: Concerning fertilization: Successful fertilization normally occurs from 16-24 hours following ovulation.
Definition
False. It occurs before 24 hours following ovulation (the period of viability of the ovum) and normally occurs within 12 hours after ovulation
Term
T/F: Concerning fertilization: At the time of fertilization the ovum has reached the isthmus of the uterine tube.
Definition
False. The ovum remains in the ampulla of the uterine tube because its size (due to corona radiata) prevents entrance into the isthmus.
Term
T/F: Concerning fertilization: The mean time of birth is 38 weeks following fertilization
Definition
True
Term
Concerning attachment of the blastocyst:
1. When does this usually occur (days post-fertilization)?
2. Where does this usually occur?
3. What complications can arise?
Definition
1. 6 days post-fertilization
2. Most common=posterior wall of uterus; less common=anterior wall of uterus
3. Complications arise when implantation near cervix or within uterine tube (ectopic pregnancy)
Term
Implantation of the blastocyst occurs after (1) produces receptors for uterine epithelium
Definition
1. Trophoblast
Term
Pregnancy tests test for the presence of (1). This is first produced by the (2).
Definition
1. Human Chorionic Gonadotropin (HCG)
2. Syncytiotrophoblast
Term
T/F: Concerning the chorion: It is composed of trophoblast lined by connective tissue derived from extraembryonic mesoderm
Definition
True
Term
T/F: Concerning the chorion: The chorionic cavity is derived from the extraembryonic coelom
Definition
True
Term
T/F: Concerning the chorion: The chorionic cavity is ultimately obliterated.
Definition
True
Term
T/F: Concerning the chorion: The villous chorion has the same DNA as the fetus, not the mother
Definition
True
Term
The placenta is comprised of two components. What are they?
Definition
Villous chorion and deciduas basalis.
Term
At the time of implantation the blastocyst is composed of
Definition
Cytotrophoblast (outer layer) and embryoblast (inner layer)
Term
The finger-like out-pocketing of the endoderm of the yolk sac just caudal to, right adjacent to, the cloacal membrane is called the (1).
Definition
Allantoic diverticulum.
Term
The primitive streak is derived from (1). It is the source of what for the embryo?
Definition
1. Epiblast cells.
Primitive streak is the source of striated muscle of the abdominal wall and most of the cells of the body wall.
Term
T/F: Concerning the primitive streak: It consists solely of proliferating epiblast
Definition
True
Term
T/F: Concerning the primitive streak: It is induced to form by the underlying notochord
Definition
False. The primitive streak gives rise to the notochord
Term
T/F: Concerning the primitive streak: It is the source of the body's epidermis
Definition
False. It is the source of striated muscle of cells of the abdominal wall and of most of the cells in the body wall (mesoderm)
Term
T/F: Concerning the primitive streak: Its first appearance coincides with the initiation of implantation
Definition
False. Implantation occurs before the development of the primitive streak.
Term
T/F: Concerning somites: They form as a result of segmentation of the lateral plate mesoderm
Definition
False. They form as a result of segmentation of paraxial mesoderm
Term
T/F: Concerning somites: They give rise to the dorsal root and autonomic ganglia.
Definition
False. Neural crest cells give rise to the dorsal root and autonomic ganglia.
Term
T/F: Concerning somites: They give rise to the nucleus pulposi of intervertebral discs
Definition
False. The notochord gives rise to the nucleus pulposi of intervertebral discs
Term
T/F: Concerning somites: They give rise to all the striated muscle of the trunk
Definition
True
Term
T/F: Concerning somites: Failure to form in the sacrococcygeal region leads to the condition known as spinal dermal sinus.
Definition
False. Spinal dermal sinus is an anomaly of neural tube closure characterized by a midline pit or dimple in the skin of the back marking the site where the epidermis was connected to the neural tube during the final stage of neural tube closure.
Term
T/F: Concerning amniotic fluid: Failure of the fetus to absorb swallowed amniotic fluid is one factor that might cause its volume to decline
Definition
False. It would cause its volume to increase. This condition is known as esophageal or duodenal atresia and it leads to polyhydramnios.
Term
Define polyhydramnios. What can cause it?
Definition
Defined as more than twice the normal volume of amniotic fluid for any particular time in gestation. It can be caused by anencephaly (which disrupts neural basis of swallowing) and esophageal or duodenal atresia (which prevent swallowed fluid from being absorbed).
Term
T/F: Concerning amniotic fluid: Failure of fetal kidneys to develop is one possible cause for an increase in amniotic fluid volume
Definition
False. This condition is known as renal agenesis. It can lead to oligohydramnios (amniotic fluid volume less than half of normal).
Term
Define oligohydramnios. What can cause it?
Definition
Defined as less than half the normal volume of amniotic fluid for any particular time in gestation. Usually caused by renal agenesis (failure of fetal kidneys to develop)
Term
T/F: Concerning amniotic fluid: Too much amniotic fluid interferes with proper joint development.
Definition
False. Too little amniotic fluid (oligohydramnios) will interfere with proper joint development because the squished fetus can't move normally
Term
What are the consequences of oligohydramnios?
Definition
1. Defective development of fetal joints because the squished fetus can't move normally
2. Pulmonary hypoplasia (underdeveloped lungs)
3. Death due to compression of the umbilical cord
Term
What is pulmonary hypoplasia. What can cause it?
Definition
Underdevelopment of the fetal lungs. It is usually caused by oligohydramnios (too little amniotic fluid).
Term
T/F: Concerning amniotic fluid: Too little amniotic fluid interferes with proper lung development.
Definition
True
Term
T/F: Concerning amniotic fluid: Too much amniotic fluid causes pressure on the umbilical cord that can lead to fetal death.
Definition
False. Oligohydramnios (too little amniotic fluid) would lead to compression of the umbilical cord and fetal death.
Term
T/F: Open myelomeningocele (in clinical terminology) is one o the major fetal causes of polyhydramnios
Definition
False. Anencephaly and/or esophageal or duodenal atresia is the major cause of polyhydramnios
Term
T/F: Open myelomeningocele (in clinical terminology) is the only spinal dysraphism associated with release of alpha-fetoprotein into amniotic fluid.
Definition
True
Term
What is the only spinal dysraphism associated with release of alpha-fetoprotein into amniotic fluid?
Definition
Open myelomeningocele
Term
T/F: Open myelomeningocele (in clinical terminology) is the spinal cord's equivalent of encephalocystocele
Definition
False. Myelocystocele is the spinal cord's equivalent to encephalocystocele because it involves the spinal cord in addition to the dura and arachnoid meninges however results in complete closure of the neural tube.
Term
1. What causes open myelomeningocele? 2. Where does it usually occur? 3. What are the symptoms/complications?
Definition
1. Caused by a localized failure of the spinal neural folds to meet and fuse. 2. Usually occurs in the lumbar region. 3. Causes paralysis in body regions caudal to site. Often associated with hydrocephalus and Arnold-Chiari malformation
Term
T/F: Open myelomeningocele (in clinical terminology) arises from a failure of neural crest cells to differentiate into dorsal portions of vertebral arches
Definition
False. This is describing a meningocele or myelocystocele.
Term
1. What causes a meningocele? 2. What are the symptoms/signs?
Definition
1. Caused by a vertebral arch defect that allows the dura and arachnoid mater to protrude through the spinal column. 2. This causes a bulge beneath the skin of the back, which is often thinner than normal and often is connected to the spinal cord by a fibrous cord.
Term
1. What causes a myelocystocele? 2. What are the symptoms/signs?
Definition
1. Caused by a localized vertebral arch defect as well as improper formation of the dorsal portion of the spinal cord. The dura and arachnoid mater make a bulge beneath the skin and a portion of the dorsal spinal cord joins it. 2. May cause minor neurological deficits.
Term
What is the differences and similarities between a myelocystocele and a meningocele?
Definition
They are both caused by a localized vertebral arch defect that allows the dura and arachnoid mater to make a bulge underneath the skin of the back. The difference is that a myelocystocele also involves a defect in the dorsal portion of the spinal cord that allows it to become part of the bulge.
Term
What is the spinal cord's equivalent of encephalocystocele?
Definition
Myelocystocele, because it also involves the spinal tissue in addition to the dura and arachnoid meninges.
Term
What is the cranial equivalent of myelomeningocele? What substance can be detected in both abnormalities?
Definition
Anencephaly. Both result in the incomplete closure of the neural tube, and both can be detected by the presence of alpha fetoprotein in the amniotic fluid.
Term
T/F: Concerning partitioning of the coelomic cavity: Failure of the pleuroperitoneal fold to form on the left is associated with underdeveloped lungs
Definition
True
Term
T/F: Concerning partitioning of the coelomic cavity: Failure of the pleuroperitoneal fold to form on the right is associated with right ventricular hypoplasia
Definition
False. This would result in a Bochdalek foramen on the right with subsequent hepatic herniation. This would lead to right PULMONARY hypoplasia, not ventricular.
Term
T/F: Concerning partitioning of the coelomic cavity: Failure of the pleuropericardial fold to form on the left is associated with Bochdalek hernia
Definition
False. Failure of the pleuroperitoneal fold to form on one side (usually occurs on the left) results in Bochdalek foramen.
Term
What is Bochdalek foramen and how is it significant?
Definition
Bochdalek foramen is caused by a failure of the pleuroperitoneal membrane (also referred to as fold) to form, resulting in an open communication between pleural cavity and peritoneal cavity. The abdominal contents can herniate through and cause pulmonary hypoplasia (underdevelopment of the lungs).
Term
T/F: Concerning partitioning of the coelomic cavity: Open communication of the pleural and peritoneal cavities will occur if myotome cells from the 3rd-5th cervical somites fail to enter the septum transversum
Definition
False. This would result in a failure of the diaphragmatic muscles to form (which would be fatal) since they are derived from the 3rd-5th cervical hypaxial dermomyotomes. This would NOT result in Bochdalek foramen specifically.
Term
T/F: Twin-twin transfusion syndrome occurs only in monozygotic twins
Definition
True
Term
T/F: Twin-twin transfusion syndrome occurs only if there is one chorion
Definition
True
Term
T/F: Twin-twin transfusion syndrome occurs only if there is one placenta
Definition
True
Term
T/F: Twin-twin transfusion syndrome is characterized by one oligohydramniotic and one polyhydramniotic twin
Definition
True
Term
What are the complications of polyhydramnios?
Definition
Cardiac problems (CHD) due to the heart having to pump harder against the increased fluid.
Term
What causes Twin-Twin Transfusion Syndrome?
Definition
Is caused by a arteriovenous anastomosis in the placenta between two monozygotic twins (with originally separate placentas). This anastomosis shunts one twin's blood into the other. Donor twin is smaller and oligohydramniotic. Recipient is polyhydramniotic and normal-sized.
Term
T/F: Fertilization of an ovum by two sperm is more likely to occur if an ovary releases two ova or if the right and left ovaries release ova simultaneously
Definition
False. This would result in dizygotic twins.
Term
T/F: Fertilization of an ovum by two sperm is the second leading cause of monochorionic monoamniotic twins
Definition
False. Monochorionic monoamniotic twins arise when two primitive streaks form within a single embryonic disc.
Term
T/F: Fertilization of an ovum by two sperm is usually prevented by a change in the properties of the zona pellucida soon after the first sperm enters the ovum
Definition
True.
Term
T/F: Fertilization of an ovum by two sperm increases in frequency with maternal age and tends to run in families
Definition
False. Age increases the chance of various complications of birth and of certain birth defects, but not of polyspermy.
Term
T/F: Commencement of blood circulation is associated with the fourth week of development
Definition
False. The circulatory system is active by the end of the 3rd week.
Term
When does the circulatory system become active?
Definition
By the end of the 3rd week (21 days)
Term
T/F: Commencement of hCG (human chorionic gonadotropin) secretion is associated with the fourth week of development
Definition
False. hCG can be detected during the end of the 2nd week (14 days)
Term
When can you detect the pregnancy? What test?
Definition
By the end of the 2nd week post-fertilization via hCG (produced by the syntrophoblast). Note: This is the time when the woman would be "late" for her next menstruation.
Term
T/F: Obliteration of uterine cavity by the expanding chorion is associated with the fourth week of development
Definition
False. Obliteration of the uterine cavity by the expanding chorion occurs early in the 3rd month.
Term
When is the uterine cavity obliterated by the expanding chorion?
Definition
Early in the 3rd month
Term
T/F: Mesodermal formation is associated with the fourth week of development
Definition
False. Mesodermal formation occurs by the end of the 2nd week via the primitive streak.
Term
When does mesodermal formation occur?
Definition
During the 2nd week via the primitive streak.
Term
T/F: Neural tube closure is associated with the fourth week of development
Definition
True
Term
When does neural tube closure occur?
Definition
During the 4th week
Term
T/F: Concerning the umbilical cord: It's outer layer is skin
Definition
False. The outer layer of the umbilical cord is the amnion
Term
What comprises the outer layer of the umbilical cord?
Definition
The amnion
Term
T/F: Concerning the umbilical cord: It's outer layer is chorion
Definition
False. The outer layer of the umbilical cord is the amnion
Term
T/F: Concerning the umbilical cord: It is surrounded by the fluid of the extraembryonic coelom
Definition
False. It is surrounded by fluid of the amniotic cavity
Term
T/F: Concerning the umbilical cord: It provides room for the development of the small intestine.
Definition
True
Term
How is the umbilical cord important to the development of the midgut?
Definition
It houses the future ileum during the 7th-10th weeks of development via the herniation of the midgut into the umbilical cord.
Term
T/F: Concerning the umbilical cord: Ladd's bands may be produced when it tears
Definition
False. Ladd's bands are caused by malrotation of the intestine. Tearing of the umbilical cord may result in gastroschisis if it occurs during the period of physiologic herniation of the midgut
Term
What is an omphalocele?
Definition
It is the presence of intestine in the umbilical cord at birth and results from failure of the midgut to return from its physiologic umbilical herniation. Alpha fetoprotein may be detected in amniotic fluid and it is associated with cardiac and renal abnormalities
Term
What is gastroschisis?
Definition
It is caused by a tear in the umbilical cord during the period of physiologic midgut herniation. The midgut becomes exposed directly to amniotic fluid and therefore alpha fetoprotein can be detected in amniotic fluid. At birth, the umbilical cord is healed however part of the bowel protrudes through a gap in the abdominal wall.
Term
What are Ladd's bands and how do they form?
Definition
Ladd's bands are formed by malrotation of the intestine. This leads to the cecum being attached to the abdominal wall by a fibrous stalk of peritoneal tissue. Often this causes an obstruction of the duodenum.
Term
T/F: One of the reasons most of the pancreatic secretory volume normally enters the duodenum at the same site as does bile is the duct of the ventral pancreas establishes a connection with the duct of the dorsal pancreas
Definition
True
Term
Why does most of the secretory volume of the ventral pancreas enter the duodenum at the same site as bile?
Definition
Because the dorsal pancreas establishes a connection with the duct of the ventral pancreas which shares a connection with the bile duct. This is the main pancreatic duct of Wirsung.
Term
What is the duct of Santorini and how is it embryologically relevant?
Definition
It is the original duct of the dorsal pancreas. It may be completely lost during development due to the established connection of the ventral pancreas to the dorsal pancreas via the main pancreatic duct of Wirsung.
Term
T/F: One of the reasons most of the pancreatic secretory volume normally enters the duodenum at the same site as does bile is the dorsal pancreas and liver arise from a common diverticulum
Definition
False. The ventral pancreas and liver arise from a common diverticulum (the hepatopancreatic diverticulum)
Term
T/F: One of the reasons most of the pancreatic secretory volume normally enters the duodenum at the same site as does bile is the entire second part of the duodenum is derived from the foregut
Definition
False. Only the first part of the duodenum is derived from the foregut. The rest is derived from the midgut.
Term
T/F: One of the reasons most of the pancreatic secretory volume normally enters the duodenum at the same site as does bile is the uncinate process of the pancreas is derived from the ventral pancreas
Definition
False. Although the ventral pancreas does become the uncinate process and head of the pancreas, it does not answer the question.
Term
What does the ventral pancreas become?
Definition
The uncinate process and the head of the pancreas
Term
What does the dorsal pancreas become?
Definition
The neck, body, and tail of the pancreas
Term
T/F: One of the reasons most of the pancreatic secretory volume normally enters the duodenum at the same site as does bile is the final stage of normal pancreatic development results in migration of the common bile duct opening onto the dorsal surface of the duodenum
Definition
False. While this is true anatomically, the rotation of the common bile duct opening is caused by rotation of the duodenum NOT the duct itself. This answer also does not answer the question.
Term
T/F: The developmental reason that the SMA is the source of the right hepatic artery in ~25% of adults is the right lobe of the liver may be derived from the segment of the midgut caudal to the vitelline duct
Definition
False. The segment caudal to the vitelline duct is the hindgut
Term
T/F: The developmental reason that the SMA is the source of the right hepatic artery in ~25% of adults is the liver arises from a diverticulum adjacent to the cranial border of the midgut
Definition
True. Dr. Stern indicates this difference may be as small as 50 microns more caudal than normal. If so, part of liver will be supplied by SMA.
Term
T/F: The developmental reason that the SMA is the source of the right hepatic artery in ~25% of adults is the liver grows into the septum transversum, which is supplied by the SMA
Definition
False. Although it is true the liver grows into the septum transversum, the septum transversum is supplied entirely by the celiac artery.
Term
T/F: The developmental reason that the SMA is the source of the right hepatic artery in ~25% of adults is the SMA is the main supply of the caudal one-quarter of the abdominal foregut
Definition
False. This is a tricky question that relates to the formation of the duodenum. Recall that only the most proximal portion of the duodenum is derived from the foregut. The rest is midgut (and thus supplied by the SMA)
Term
T/F: The developmental reason that the SMA is the source of the right hepatic artery in ~25% of adults is the arterial supply to the liver is established after the duodenum becomes retroperitoneal.
Definition
False. The arterial supply occurs before this happens.
Term
What is the developmental reason the SMA is the source of the right hepatic artery in ~25% of adults?
Definition
The liver arises from a diverticulum (cystic diverticulum) adjacent to the cranial border of the midgut. If this happens just caudal to what is normal, the SMA (which supplies the midgut) will provide part of the arterial supply to the liver
Term
T/F: Concerning Meckel's diverticulum: It is an inconsistent remnant of the allantoic duct
Definition
False. It is a remnant of the vitelline duct
Term
T/F: Concerning Meckel's diverticulum: Its presence is associated with cardiac defects
Definition
False. Its presence is associated with GI defects similar to appendicitis.
Term
T/F: Concerning Meckel's diverticulum: It attaches to the antimesenteric border of the ileum
Definition
True
Term
T/F: Concerning Meckel's diverticulum: It may contain splenic tissue
Definition
False. It may contain aberrant gastric and/or pancreatic tissue, but not splenic.
Term
What is a Meckel's diverticulum?
Definition
It is a persistence of a portion of the vitelline duct closest to the midgut (about 2" long and 2 feet proximal to ileocecal valve). It attaches to the antimesenteric border of the ileum. It can become infected like an appendix and may contain aberrant gastric and/or pancreatic tissue
Term
T/F: Concerning Hirchsprung's disease: It is associated with polyhydramnios
Definition
False. It does not lead to problems swallowing or any renal problems
Term
T/F: Concerning Hirchsprung's disease: It is associated postnatally with diarrhea and painful urination.
Definition
False. It is associated with delayed passage of meconium, constipation, and painful defecation
Term
T/F: Concerning Hirchsprung's disease: It is fundamentally a defect in neural crest migration
Definition
True
Term
T/F: Concerning Hirchsprung's disease: It usually involves the distal ileum, cecum, and appendix
Definition
False. It usually involves the sigmoid colon and rectum. (95% of time it is distal to splenic flexure).
Term
What causes Hirchsprung's disease?
Definition
It is caused by a problem with neural crest migration into the large intestine (usually confined to the sigmoid colon and rectum). This leads to an aganglionic portion of the intestine as these neural crest cells provide postganglionic parasympathetic innervation. Result is aperistalsis, delayed passage of meconium, constipation, and painful defecation.
Term
T/F: Concerning gastroschisis: It involves direct contact of the bowel wall with amniotic fluid
Definition
True
Term
T/F: Concerning gastroschisis: It is associated with few other congenital defects
Definition
True
Term
T/F: Concerning gastroschisis: The involved segment of the bowel is inflamed
Definition
True
Term
T/F: Concerning gastroschisis: It may be associated with alpha-fetoprotein in the amniotic fluid
Definition
True
Term
Which of the following adult structures are not derived from the embryonic aortic arches:
1. Arch of the aorta
2. Ligamentum arteriosum
3. Pulmonary arteries
4. Ascending aorta
5. Common carotid arteries
Definition
Answer: Ascending aorta
1. 4th aortic arch
2. 6th aortic arch
3. 6th aortic arch
5. 3rd aortic arch
Term
What aortic arch gives rise to the arch of the aorta?
Definition
4th
Term
What aortic arch gives rise to the ligamentum arteriosum in the adult?
Definition
6th
Term
What aortic arch gives rise to the pulmonary arteries?
Definition
6th
Term
What aortic arch gives rise to the common carotid arteries?
Definition
3rd
Term
T/F: During embryonic and fetal development the umbilical arteries carry well-oxygenated blood
Definition
False. The umbilical vein carries well-oxygenated blood
Term
T/F: During embryonic and fetal development the pulmonary arteries carry well-oxygenated blood
Definition
False. Most of the blood is shunted from the pulmonary trunk to the aortic arch via the ductus arteriosus. The blood that makes it to the lungs is of a moderate oxygen content.
Term
T/F: During embryonic and fetal development the post hepatic portion of the IVC carries well-oxygenated blood
Definition
True
Term
T/F: During embryonic and fetal development the ductus venosus carries poorly oxygenated blood
Definition
False. The ductus venosus shunts blood from the umbilical vein to the IVC and therefore carries well-oxygenated blood.
Term
T/F: During embryonic and fetal development the SVC carries well-oxygenated blood
Definition
False. The SVC is returning blood from the cranial region of the fetus to the heart. This blood is poorly oxygenated
Term
Tetralogy of Fallot is a set of cardiac defects stemming from an unequal division of the truncus arteriosus. What are those defects?
Definition
1. Pulmonary stenosis
2. Right ventricular hypertrophy
3. Interventricular septal defect
4. Overriding aorta
Term
T/F: Cardiac development begins in the intraembryonic mesoderm anterior to the prochordal plate during the 3rd week of development
Definition
True
Term
T/F: Failure of the truncal ridges to spiral results in transposition of the great vessels
Definition
True
Term
T/F: The sinus venarum is the smooth-walled part of the right atrium derived from the sinus venosus
Definition
True
Term
T/F: The foramen primum is normally obliterated during embryonic development
Definition
True (it is replaced by the foramen ovale)
Term
T/F: The bulboventricular loop bends toward the left, producing the leftward position of the ventricles in adult heart anatomy
Definition
False. It bends to the right
Term
T/F: Concerning development of the heart: The interatrial septum is formed by fusion of the septum primum and septum secundum
Definition
True
Term
T/F: Concerning development of the heart: Closure of the foramen ovale after birth is accomplished by fusion of the septum secundum to the endocardial cushions
Definition
False. It is accomplished by fusion of the septum primum to the septum secundum
Term
T/F: Concerning development of the heart: The adult left ventricle is derived entirely from the primitive embryonic ventricle
Definition
False. It is derived from the primitive embryonic ventricle and the bulbus cordis, truncal ridges, and endocardial cushions.
Term
T/F: Concerning development of the heart: The embryonic bulbus cordis gives rise to the ascending aorta in the adult
Definition
False. The aortic sac gives rise to the ascending aorta
Term
T/F: Concerning development of the heart: The only remnant of the primitive atrium in the adult is the auricle of the left atrium
Definition
False. The primitive atrium turns into the trabeculated part of right and left atria and both auricles.
Term
What do the 3rd aortic arches turn into?
Definition
Common carotid arteries (right and left)
Term
What do the 4th aortic arches turn into?
Definition
Right become right subclavian artery (proximal part).
Left becomes part of the aortic arch
Term
What do the 6th aortic arches turn into?
Definition
Right becomes the pulmonary trunk and pulmonary arteries
Left becomes ductus arteriosus (ligamentum arteriousus in adult)
Term
What does the truncus arteriosus turn into?
Definition
The initial parts of ascending aorta and pulmonary trunk
Term
What do the 7th intersegmental arteries turn into?
Definition
Right becomes distal part of right subclavian artery
Left becomes the left subclavian artery
Term
What do the embryonic dorsal aortae become?
Definition
Fuse to become the descending aorta
Term
What does the aortic sac become in the adult?
Definition
The ascending aorta and brachiocephalic artery
Term
What do the longitudinal anastomosis between the first 7 intersegmental arteries become?
Definition
The vertebral arteries (the 7th intersegmentals become the portions of the subclavian aa so this makes sense).
Term
What does the bulbus cordis become?
Definition
Smooth parts of right and left ventricles
Term
What does the primitive ventricle become?
Definition
The trabeculated part of right and left ventricles
Term
What does the primitive atrium become?
Definition
The trabeculated part of the right and left atria. Right and left auricles
Term
What does the sinus venosus become?
Definition
The smooth-walled portion of the right atrium
Term
What does the embryonic umbilical artery become?
Definition
The adult umbilical artery (serves the bladder). Obliterated distal portion.
Term
What is the most common type of cardiac defect?
Definition
Membranous type ventricular septal defect
Term
T/F: Concerning derivatives of pharyngeal pouches: The first pouch becomes the lining of the external auditory meatus
Definition
False. It becomes the eustachian tube and middle ear cavity. The 1st branchial cleft becomes the lining of the external auditory meatus
Term
What does the first pharyngeal pouch become?
Definition
The eustachian tube and middle ear cavity
Term
What does the first branchial cleft become?
Definition
The lining of the external auditory meatus
Term
T/F: Concerning derivatives of pharyngeal pouches: The second pouch becomes the epithelium overlying the palatine tonsil
Definition
True
Term
What does the second pharyngeal pouch become?
Definition
The epithelium overlying the palatine tonsils.
Term
T/F: Concerning derivatives of pharyngeal pouches: The third pouch becomes a lobe of the thyroid gland
Definition
False. The third pouch becomes the inferior parathyroid gland and nonlymphoid part of the thymus.
Term
What does the third pharyngeal pouch become?
Definition
The inferior parathyroid gland and nonlymphoid part of the thymus
Term
T/F: Concerning derivatives of pharyngeal pouches: The fourth pouch becomes the nonlymphoid part of the thymus
Definition
False. The fourth pouch becomes the superior parathyroid gland and C cells (calcitonin-secreting cells) of the thyroid gland
Term
What does the fourth pharyngeal pouch become?
Definition
The superior parathyroid gland and C cells (calcitonin-secreting cells) of the thyroid gland
Term
T/F: Concerning derivatives of pharyngeal pouches: The sixth pouch becomes a lung
Definition
False. This is a tricky question. Specifically, the 6th gives rise to the laryngeal diverticulum, which becomes the lung
Term
What does the sixth pharyngeal pouch become?
Definition
The laryngeal diverticulum (which eventually forms the lungs)
Term
T/F: Concerning branchial arches: The mesenchyme filling all arches is derived predominantly from neural crest cells
Definition
True. Specifically this is call ectomesenchyme
Term
T/F: Concerning branchial arches: The cartilage of the first arch gives rise to the malleus and incus
Definition
True
Term
T/F: Concerning branchial arches: The striated muscles derived from somitomere cells entering the second arch become muscles innervated by the facial nerve (CN7)
Definition
True
Term
T/F: Concerning branchial arches: The external surfaces of the 3rd-6th arches become buried beneath the skin of the neck
Definition
True
Term
What does the cartilage of the first branchial arch become?
Definition
Malleus and incus of middle ear. The sphenomandibular ligament
Term
What does the cartilage of the second branchial arch become?
Definition
Stapes, styloid process of temporal bone, lesser horn of hyoid bone, superior portion of the body of the hyoid bone
Term
What does the cartilage of the 3rd branchial arch become?
Definition
Greater horn of the hyoid bone and most of the body of the hyoid bone
Term
What does the cartilage of the 4th branchial arch become?
Definition
Degenerates
Term
What does the cartilage of the 6th branchial arch become?
Definition
Degenerates
Term
What happens to the 5th branchial arch?
Definition
It does not form but for a small nub
Term
What does the ectomesenchyme ventral to pharynx become?
Definition
Connective tissue of tongue and epiglottis
Term
What happens to the external regions of the 3rd-6th branchial arches?
Definition
Become buried beneath the skin of the neck
Term
What provides innervation to the muscles derived from the 1st branchial arch?
Definition
Trigeminal nerve (CN5)
Term
What provides innervation to the muscles derived from the 2nd branchial arch?
Definition
Facial nerve (CN7)
Term
What is the most common anomaly arising from a defect in development of the thyroid diverticulum?
Definition
A thyroglossal cyst (cyst located beneath the skin of the anterior surface of the neck, just inferior to the hyoid bone)
Term
What gives rise to the muscles of facial expression?
Definition
Occipital dermomyotomes and somitomeres of the second branchial arch
Term
What causes a lingual thyroid and what are its symptoms?
Definition
Occurs when thyroid tissue is left behind embedded in the tongue. If the mass is large it can lead to dysphagia, dysphonia, and/or dyspnea. Majority of persons with symptomatic lingual thyroid have no thyroid gland in the neck
Term
What causes a thyroglossal cyst? How is it detected?
Definition
Occurs when a portion of the thyroglossal duct persists. This causes a cyst to be formed beneath the skin of the anterior surface of the neck, just inferior to the hyoid bone. The mass will move superiorly when the child protrudes his/her tongue
Term
What major structure arises as an outpocketing of the floor of the pharynx between the copula caudally and the median tongue bud cranially?
Definition
Thyroid gland
Term
What is a recognizable anomaly of parathyroid development? How does this occur?
Definition
Location of the inferior parathyroids in the mediastinum near the thymus. Caused by inferior parathyroids continuing their attachment to the portion associated with the thymus for too long (they are dragged into the mediastinum).
Term
What causes a pyramidal lobe of the thyroid gland?
Definition
When a portion of the thyroglossal duct persists and fills in with glandular tissue
Term
T/F: Both cleft lips and cleft palates can occur unilaterally or bilaterally
Definition
True
Term
T/F: Cleft lip results from a failure of the intermaxillary segment and maxillary prominence to completely merge or fuse
Definition
False. Cleft lip results from a failure of the maxillary prominence to fuse with one (unilateral) or both (bilateral) medial nasal prominences
Term
What causes a bilateral cleft lip?
Definition
Failure of the maxillary prominences fail to fuse completely with both medial nasal prominences
Term
T/F: The lateral nasal prominences give rise to the nasal septum
Definition
False. The medial nasal prominences give rise to the nasal septum
Term
What causes a unilateral cleft lip?
Definition
Failure of the maxillary prominence to merge with the medial nasal prominence of the affected side
Term
What causes median cleft lip?
Definition
Failure of the medial nasal prominences to fuse
Term
What causes a median cleft lower lip and/or cleft mandible?
Definition
Failure of the mandibular prominences to fuse
Term
T/F: A median cleft of the lower lip results from a failure of the left and right mandibular prominences to completely merge or fuse
Definition
True
Term
T/F: Cleft palate results from the failure of the primary and secondary palates to fuse together
Definition
True
Term
T/F: Cleft lip is more common in males than in females
Definition
True
Term
What causes an oblique facial cleft?
Definition
Failure of the maxillary prominence to fuse with both a medial nasal prominence and a lateral nasal prominence. They can be unilateral or bilateral. The affected side will not have a nasolacrimal duct.
Term
What causes a unilateral secondary cleft palate?
Definition
Failure of one of the lateral palatine processes to fuse with the other and the nasal septum
Term
What causes a bilateral secondary cleft palate?
Definition
Failure of both lateral palatine processes to fuse with each other and the nasal septum
Term
What causes a unilateral primary cleft palate?
Definition
Failure of one medial nasal prominence to fuse with the lateral palatine process and/or maxillary prominence
Term
What causes a bilateral primary cleft palate?
Definition
Failure of both medial nasal prominences to fuse with the lateral palatine processes and/or maxillary prominences
Term
T/F: Cleft palate is more common in males than in females?
Definition
False. It is more common in females
Term
T/F: The nasolacrimal groove develops between the maxillary prominence and the nasofrontal prominence
Definition
True
Term
How does the nasolacrimal duct form?
Definition
Precluded by the fusion of the maxillary prominence with the medial nasal prominence and lateral nasal prominence. It develops between the maxillary prominence and the nasofrontal prominence
Term
T/F: The fused medial nasal prominences give rise to the philtrum, premaxilla, and the primary palate?
Definition
True
Term
What does the fused medial nasal prominences give rise to?
Definition
1. Philtrum
2. Premaxilla
3. Primary palate
Term
What do the lateral nasal prominences give rise to?
Definition
Alar cartilage of nose
Term
T/F: The soft palate is derived from the lateral palatine processes (palatal shelves)
Definition
True
Term
T/F: The maxillary and mandibular prominences are produced by mesenchyme derived from neural crest cells
Definition
True. Specifically this is called ectomesenchyme
Term
T/F: With respect to the development of the urinary system: The urinary bladder is a derivative of the cloaca
Definition
True
Term
What does the cloaca become in the adult?
Definition
Urinary bladder
Term
T/F: With respect to the development of the urinary system: The human kidney is derived from both the mesonephric duct and metanephric blastema
Definition
True
Term
What do the mesonephric ducts become?
Definition
Uteric buds that differentiate into the ureter, calyces, and pyramids.
Term
What does the metanephric blastema become?
Definition
The nephrons of the kidney
Term
T/F: With respect to the development of the urinary system: The suprarenal gland develops independently from the kidney
Definition
True. Specifically it is a derivative of neural crest cells
Term
T/F: With respect to congenital anomalies of the urinary system: Urachal fistulas connect the urinary bladder to the rectum
Definition
False. Urachal fistulas connect the urinary bladder to the umbilicus
Term
What causes a urachal fistula?
Definition
Caused by a persisting (patent) allantois that results in an open communication (fistula) between the bladder and umbilicus. This can lead to leakage of urine from the belly button
Term
T/F: With respect to congenital anomalies of the urinary system: Supernumerary renal vessels (arteries and veins) are rare
Definition
False. They are relatively common
Term
What are some complications of supernumerary renal vessels? Are these vessels likely to be venous or arterial in nature?
Definition
They may compress the ureter. They are more likely to be arterial
Term
T/F: With respect to congenital anomalies of the urinary system: Polycystic kidneys are usually associated with duplication of the uretic bud
Definition
False. Polycystic kidney disease is an autosomal recessive disorder in which the kidney contains hundreds of small cysts that result in damage to the functional renal tissues.
Term
What causes polycystic kidney disease?
Definition
Polycystic kidney disease is an autosomal recessive disorder in which the kidney contains hundreds of small cysts that result in damage to the functional renal tissues.
Term
T/F: With respect to congenital anomalies of the urinary system: Urinary incontinence is a possible symptom of ureteric duplication
Definition
True
Term
What can result from ureteric duplication?
Definition
Urinary incontinence because the sphinctor urethrae cannot control the extra orifices. In a female they can open into the vagina
Term
T/F: With respect to congenital anomalies of the urinary system: Ectopic "horseshoe" kidneys are usually trapped during ascent by the SMA
Definition
False. They are trapped during ascent by the IMA
Term
T/F: With respect to the development of the gonadal-genital system: Ovaries arise primarily from the medulla of the undifferentiated gonad
Definition
False. Ovaries arise primarily from the cortex of the undifferentiated gonad
Term
T/F: With respect to congenital anomalies of the gonadal-genital system: Androgen insensitivity is the cause of the "andrenogenital" syndrome in female pseudo-hermaphrodites
Definition
False. Androgen insensitivity results in a externally phenotypically normal female however there is no uterus and there are testes instead of ovaries.
Term
T/F: With respect to the development of the gonadal-genital system: The prostate gland is derived from the mesonephric duct
Definition
False. The prostate is derived from the urogenital sinus
Term
T/F: With respect to the development of the gonadal-genital system: The uterovaginal primordium is created by the caudal fusion of the paramesonephric ducts
Definition
True
Term
T/F: With respect to the development of the gonadal-genital system: The phallus gives rise to the penis only
Definition
False. It gives rise to the penis in the male and the clitoris in the female
Term
T/F: With respect to congenital anomalies of the gonadal-genital system: Hypospadias is often observed in conjunction with exstrophy of the bladder
Definition
False. Epispadias is observed in conjunction with extrophy of the bladder
Term
T/F: With respect to congenital anomalies of the gonadal-genital system: Vaginal atresia can result if sinovaginal bulbs fail to develop
Definition
True
Term
T/F: With respect to congenital anomalies of the gonadal-genital system: Only one X-chromosome is required for the development of the normal female phenotype
Definition
False. You need two for a fertile female phenotype. This is describing Turner's syndrome
Term
What does the mesonephric duct differentiate into for the male?
Definition
Ureter, ejaculatory duct, seminal vesicle, epididymis, vas deferens
Term
What does the mesonephric duct differentiate into for the female
Definition
Nothing. Certain components of the female genital/gonad are derived from the paramesonephric duct
Term
What does the paramesonephric duct differentiate into for the male?
Definition
Nothing. Certain components of the male genital/gonad are derived from the mesonephric duct
Term
What does the paramesonephric duct differentiate into for the female?
Definition
Uterus, uterine tube, upper portion of the vagina
Term
What does the urogenital sinus become for the male?
Definition
Urinary bladder, penile urethra, bulbourethral glands, and prostate
Term
What does the urogenital sinus become for the female?
Definition
Urinary bladder, greater vestibular glands, and lower portion of the vagina
Term
The round ligament of the uterus is homologous with the (1) in the male?
Definition
Gubernaculum of testes
Term
The gubernaculum of testes is homologous with the (1) in the female?
Definition
Round ligament of the uterus
Term
The bulb of the vestibule is homologous with the (1) in the male?
Definition
Corpus spongiosum of the penis
Term
The corpus spongiosum of the penis is homologous with the (1) in the female?
Definition
Bulb of vestibule
Term
The labia majora is homologous with the (1) in the male?
Definition
Scrotum
Term
The scrotum is homologous with the (1) in the female?
Definition
Labia majora
Term
The vestibule of the vagina is homologous with the (1) in the male?
Definition
Penile urethra
Term
The penile urethra is homologous with the (1) in the female?
Definition
Vestibule of vagina
Term
The mesonephric tubules in the female are homologous with the (1) in the male?
Definition
Efferent ductules of testes
Term
The efferent ductules of testes in the male are homologous with the (1) in the female?
Definition
Mesonephric tubules
Term
The labia minora is homologous with (1) in the male?
Definition
Ventral penis
Term
The ventral penis is homologous with (1) in the female?
Definition
Labia minora
Term
What are Gartner's ducts?
Definition
Persistent remnant of the mesonephric duct in females
Term
What is hypospadias of the penis? Is it associated with any other complications?
Definition
An incomplete fusion of the ventral penis. No other complications
Term
what is epispadias of the penis? Is it associated with any other complications?
Definition
An incomplete fusion of the dorsal penis. It is often associated with a failure of closure of the anterior abdominal wall which often results in protrusion of the urinary bladder
Term
What is agenesis of the vagina?
Definition
A failure of the vagina to form due to failure of the sinovaginal bulbs to develop and form the vaginal plate
Term
What is andrenogenital syndrome?
Definition
Occurs in females when the vagina opens into the urinary bladder, which results in a persistent urogenital sinus (which allows the bladder and uterus to be exposed to the outside world). It also may result in an enlarged clitoris
Term
What is the opercular process and what does it form from?
Definition
It is a component of the lateral aspect of the neck. It grows out of the 2nd branchial arch caudally and meets up with the epipericardial ridge (from the 6th branchial arch)
Term
What is the epipericardial ridge and what does it form from?
Definition
it is a component of the lateral aspect of the neck. It grows out of the 6th branchial arch cranially and meets up with the opercular process (from the 2nd branchial arch)
Term
How does a lateral cervical (branchial) cyst form?
Definition
Formed in the lateral portion of neck due to persistence of the cervical sinus.
Term
When the opercular process and epipericardial ridge fuse, what is formed? What happens to it?
Definition
Cervical sinus. It is filled in by ectomesenchyme to form the lateral neck.
Term
How does an external branchial sinus form?
Definition
From the persistence of the cervical sinus compounded with failure of fusion of the opercular process and epipericardial ridge. The sinus will open onto the external lateral portion of the neck.
Term
How does an internal branchial sinus form?
Definition
From the persistence of the cervical sinus compounded with the rupture of a pharyngeal pouch. If 2nd pouch ruptures, will open through palatine tonsil. If 3rd pouch ruptures, will open through the thyrohyoid membrane
Term
How does a branchial fistula form?
Definition
From the persistence of the cervical sinus compounded with failure of fusion of opercular process and epipericardial ridge, along with rupture of a pharyngeal pouch. This allows for communication to be established between pharynx and external lateral neck
Term
What is a ligament thyroglossal?
Definition
Is the result of a small remnant of the thyroid diverticulum that remains in the neck
Term
What is mandibulofacial dysostoses?
Definition
Occurs when the neural crest cells destined to populate the first branchial arch fail to do so. This results in MAJOR deformities of the maxilla, mandible and ears
Term
Define DiGeorge's syndrome
Definition
Occurs when there is improper migration of neural crest cells into the 3rd and 4th branchial arches. Causes minor deformations of the lower face combined with thymic and parathyroid aplasia and problems with aorticopulmonary septation
Term
What causes congenital retinal detachment?
Definition
When the inner and outer layers of the optic cup fail to fuse, resulting in detachment of the retina.
Term
Between what two layers of the retina does retinal detachment occur?
Definition
Neural and pigmented layers of the retina
Term
What causes coloboma of the iris and retina?
Definition
Defective closure of the optic fissure
Term
What is the abdominal diaphragm derived from?
Definition
1. Septum transversum (central tendon of diaphragm)
2. Pleuroperitoneal membranes
3. 3rd-5th cervical hypaxial dermomyotomes
4. Derived entirely from mesoderm
Term
What comprises the chorion?
Definition
Trophoblast lined by connective tissue derived from extraembyronic mesoderm
Term
What is the chorionic cavity derived from?
Definition
Extraembryonic coelom
Term
What causes esophageal atresia? What is it associated with?
Definition
Caused by improper recanalization of the esophagus or stenosis of the esophagus. They are associated with a fistula between the abnormal esophagus and trachea and polyhydramnios
Term
What are characteristics of dizygotic twins?
Definition
Two oocytes leading to two zygotes. Separate placenta (the two may fuse later on), separate chorion and separate amnion. THEY NEVER SHARE A COMMON AMNION.
Term
What are the three methods by which monozygotic twins can arise?
Definition
1. Early cleavage of embryo into two structures (30%)
2. Two separate inner cell masses form within a single blastocyst (69%)
3. Two primitive streaks within a single embryonic disc (<1%)
Term
What are the characteristics of monozygotic twins that arise from the splitting of the embryo early in development?
Definition
Separate placentas, chorions, and amnions (same as dizygotic twins)
Term
What are the characteristics of monozygotic twins that arise from two separate inner cell masses within a single blastocyst? Are there any complications of this?
Definition
Shared placenta and chorion. Separate amnions. This can lead to Twin-Twin Transfusion Syndrome.
Term
What are the characteristics of monozygotic twins that arise from two primitive streaks within a single embryonic disc? Are there any complications of this?
Definition
Shared placenta, chorion, and amniotic cavity. About half of these types of twins are conjoined.
Term
When do the fetal lungs become functional (from the last normal menstrual period)
Definition
24-28 weeks
Term
What does the dorsal mesentery of the hindgut become?
Definition
Sigmoid mesocolon
Term
What is the mesogastrium?
Definition
The portion of the dorsal mesentery that goes to the greater curvature of the stomach
Term
What is the mesoduodenum?
Definition
The portion of the dorsal mesentery that goes to the lesser curvature of the duodenum
Term
What does the lower mesogastrium become?
Definition
Gastrocolic ligament (from greater curvature of stomach to TV colon), part of the apron of the greater omentum. Fuses with the upper mesogastrium to become the dorsal mesogastrium
Term
What does the upper mesogastrium become?
Definition
Lienorenal ligament (spleen to kidney), gastrosplenic ligament (spleen to stomach), part of the apron of the greater omentum. Fuses with the lower mesogastrium to become the dorsal mesogastrium
Term
The greater omentum results from the fusion of what two structures?
Definition
Upper and lower mesogastrium
Term
What causes an annular pancreas? What are the complications of this?
Definition
Occurs when the ventral pancreatic diverticulum bifurcates around the duodenum. The two portions fuse which can result in duodenal obstruction
Term
What causes pancreatic divisum? What is it associated with?
Definition
Failure of fusion of the ventral and dorsal pancreatic ducts. It is associated with a higher incidence of pancreatitis
Term
T/F: Hirschprung's disease occurs mainly in males
Definition
True
Term
What causes dextrocardia?
Definition
If the aorticopulmonary septum fails to form in a spiral fashion. This causes the aorta and pulmonary trunk to be switched in position.
Term
Where do ventricular septal defects usually occur?
Definition
In the membranous portion of the septum
Term
What do the endocardial cushions contribute to?
Definition
Division of the atrioventricular canal and to the adult interventricular septum
Term
What is the most common congenital cardiac defects? Is it more common in males or females? Where does it usually occur? Does it result in cyanosis?
Definition
Ventricular septal defect. More common in males. Occurs mostly in the membranous portion of septum. Results in cyanosis.
Term
Are atrial septal defects more common in males or females? Where does the abnormality usually occur? Does it result in cyanosis?
Definition
More common in females. Interatrial septum fails to form properly (ex. patent foramen ovale). Most of the time does not result in cyanosis.
Term
Is coarctation of the aorta more common in males or females?
Definition
Males
Term
What are the symptoms of postductal coarctation of the aorta?
Definition
Upper body hypertension due to anastomoses between subclavian and intercostal aa (dilation of intercostal aa), and left ventricular hypertrophy
Term
What are the symptoms of preductal coarctation of the aorta?
Definition
Cyanosis of lower extremities because blood flow of lower extremities can't be compensated by anastomoses.
Term
What leads to atrioventricular septal defects? What is this usually affiliated with?
Definition
Failure of endocardial cushions to fuse, leaving a hole in the center of the heart, causing left-to-right shunting of blood and likely leading to congestive heart failure. This is common in Down's Syndrome.
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