aka embryonic period

when each of the germ layers gives rise to tissues

1. neural plate formation induces neuroectoderm

2. the neural plate elongates

3. lateral edges of plate elevate and meet at the midline

4. edges fuse into a tube

1. cells from the lateral border (crest) of the neural plate break away while the neural tube is forming

2. the cells change from epithelial to mesenchymal

3. BMP induces the formation, migration, proliferation, and differentation of the neural crest cells

all ganglia

connective tissue and bones of face and scull

C cells of thydoid

conotruncal seprum of the heart

odontoblasts

dermis of face and neck

adrenal medulla

schwann cells

glial cells

meninges of the forebrain

melanocytes

smooth muscle cells of blood vessels in the face and forebrain

neural tube defect

fails to close at crainial end

leads to death, inability to swallow, usually still born

neural tube fails to close in the cervical region or down farther

the patient can live fine most of the time

paraxial mesoderm on the sides of the axis

lateral plate mesoderm

somatic / parietal mesoderm

splanchnic / visceral mesoderm

formed by the parietal and visceral mesoderm

later makes the thorasic and abdominal cavity

unorganized somitomeres (first in cephalic)

later it maes organized somites which turn into muscle, dermis, skeletal, vertebre, ribs

1. VEGF activates hemangioblasts

2. hemangioblasts induce to form blood cells and blood islands (week 3)

3. blood islands form vessels

vascular endothelial growth factor

mesoderm secretes them so they induce hemangioblasts to do vasculogenesis

foregut: cranial region

heind gut: tail region

midgut

holds the ectoderm and endoderm together at the cephalic end

breaks down in week 4 connecting the amniotc cavity and the primitive gut

evuntally makes the mouth

the more minor ones someone has the more changes there are that they have a major one.

especially look at the ears, many major anomalys have malformed ears

fetal age, growth, structural abnormalities

dopplar functions can be used for fluid levels and blood flow

multiple gestations

neural tube, abdominal wall, heart, and facial defects

develop from a single fertilized egg

split a various stages

monozygotic twins

cells developing the embryo split apart into two embryos, they have their own placentas and membranes

monozygotic twins

diamniotic, monochorionic

inner cell mass splits, out cell mass does not. two babies form and share the placenta but it is early enough that they get their own amniotic sac

monozygotic twins

monoamniotic, monochorionic

2 embryos form but because development is too far along they share a chorionic and amniotic sac and a placenta

higher morbidity and mortality, 12% are premes, smaller, shorter gestation, vanishing twin, twin twin transfusion, delivery issues, conjoined

birth

factors that induce are not known, divided into 3 stages

1. effacement and dilation of cervix

2. delivery of fetus

3. delivery of placenta and membranes

clinical: from last period, 280d, 140 weeks

ours: from fertilization, 266d, 138 weeks

skin reddish and wrinkled, by the end the length is 25 cm and 1100 grams

no connective tissue or CNS maturity

villi continue to grow and expand on the embryonic pole becoming the chorion fondosum

villi on abembryonic pole degenerate (chorion leave)

forms in month 4/5

projections of the decuidia into the intervillous spaces, dont reach chorionic plate, divides placenta into cotyledons

early on LH induces progesterone secretion to develop and maintain it

if mom wasn't pregant, it would die around menstration time

if pregnat, hCG supplies the corpus leutum until the placenta can provide enough progesterone on its own and the corpus leutim dies (end of month 4)

hormone made in the synctiotrophoblast

mostly estradiol

uterine growth, mammary gland development

hormone made in the synctiotrophoblast

helps baby to moms glucose first making mom a little diabetogenic

breast development, milk production, growth hormone like

early ambilical cord

located where ectoderm meets amnion

as the amniotic cavity expands, amnion begins to envelope the connecting stalk and yolk stalk forming the umbilical cord

evuntally only umbilical vessels and Wharton's jelly will in in it

if mom has an autoimmunie disease antibodies generated by the disease may attack the fetus

ex: systemic lupus erythematosus

abormal blastocyst develops and placental tissues form, hCG is secreted from the milagnant tumor that develops

aka invasive mole or choriocarcinoma

it causes holoprosencephaly

it kills cells in the anterior midline of the germ disc making a deficiency in the midline in craniofacial structures

viscera (organs) of are reversed

some patients have respiratory issues like chronic sinusitis due to abnormal cillia (kartagner's syndrome)

they will build up in the sacctococcygeal region, they are pluripotent and proliferate and form tumors

they were supposed to migrate to the gondal ridge and differentate

it is between the top of the notochord and the buccopharyngeal membrane

it is important in induction of the forebrain

under the neural tube

basis for axial skeleton

it is at the caudal end of the disc and has a diverticulum (allantos) that extends into the connecting stalk (to the uterus)

made of ectoderm and endoderm

too much BMP4 inhibitors are made or not enough are made causing malformations in the head

ex: over expression --> head duplications, conjoined twins

gastrulation is interrupted by genetic abnormalities

the formation of the lower limbs, urogenital system, and lumbosacral vertebre is abnormal causing hypoplasia, fusion of the lower limbs, vertebral abnormalities, renal agenesis, imperforate anus, genital abnormailities

it is almost always fatal: 50% still born, 50% dead within days

transcription factor on the right lateral plate mesoderm that regulates effector grnes responsible for establishing right sidedness

the cascade is initiated on the left but cilia in the node beat to create a gradient established by gap junctions and small ion transport

1. premordial germ cells move to the gonads week 5

2. differentate into oogonia

3. divide into follicular cells

4. some stop in diplotene becoming primary oocytes, some atresia

1. follicle filles with fluid making antrum becoming mature

2. follicular cells make projections into the zona pellucida

3. granulosa makes zona pellucida

4. theca follucili --> theca interna and externa

5. cumulus oophous cells form from granulosa around oocyte

6. LH incuces completion through meiosis 2 making secondary oocyte

1. LH induces collagenases to digest stigma

2. oocyte and cuumulus oophorus cells leave

3. fimbare sweep them into the ampulla

4. cumulus oophorus --> crona radiata

day 8

cytotrophoblast and syncytriotrophoblast

cyto migrates to syncytrio

hypoblast and embryoblast

day 8

day 8

in the epiblast, some cells called amnioblasts

day 9

lacunar form in the synctotriptrophoblast

vacolules become lacunae

lining the cytotrophoblast (so the blascocele cavity) creating the primitive yolk sac

day 9

between lacunae and sinusoids

day 11/12

day 11/12

between cytotrophoblast ad exocoelomic cavity

day 11/12

in the extraembryonic mesoderm except at the connecting stalk

day 11/12

endometrium fills with glycogen and lipids around implation and then spreads to the rest of the tissue

formed day 13

cells from the cytotrphoblast protrude into the synctriotrophoblast

7 hours