Home > Flashcards > Women's & Gender Studies > Embryo of Fem/M Repro Org

Details Title: Embryo of Fem/M Repro Org Description: 4.17.07 Total Flash Cards: 74 Created: 04/21/2007 10:08:33	To study from this set of flash cards, or to create your own your own study flash cards, register HERE. If you are already a registered user, CLICK HERE.
Cards Term Why are the urinary and genital systems "interwoven?" Definition Both systems are derived from a common ridge of intermediate mesoderm that lies along the posterior abdominal wall. Term up to when are the male/female repro systems identical? Definition Up until 7 weeks, the reproductive system is indifferent, i.e., no male/female distinction. Term Where do most UG structures arise from? Definition Most UG structures arise from the intermediate mesoderm Term Where is the other part of the UG from? Definition the cloca (hindgut), which is endodermnal, and not mesodermal Term Fromt he intermediate mesoder, what system do you get? Definition the mesonephric system Term What is the mesonephric system comprised of? Definition Mesonephric system: 1. Mesonephros (which differentiated from the intermediate mesoderm), 2. Mesonephric duct (derived from Mesonephros), 3. Paramesonephric duct (derived from Mesonephric duct) Term What divides the cloca into 2 different sections? Definition the urorectal septum Term When does the cloaca divide? Definition at 5 weeks Term What does the urorectal septum % the cloaca into? Definition the urogenital sinus (ventral) and the anorectal canal (dorsal) Term hat are 2 parts of the gonads? Definition 1. the Primordial Germ cells and 2. the gonadal ridge. These are both essential because you must have cells, and a place a for them to go. Term What makes up the gonadal ridge? Definition Mesothelium lining the posterior abdominal wall, and Underlying mesenchyme Term Where do PGCs originate? Definition THEY ORIGINATE IN THE YOLK SAC ENDODERM Term wHERE do they migrate to? Definition Migrate through dorsal mesentary of hindgut to gonadal ridge, where they loose their motility Term What is another name for the mesothelium? Definition the coelomic epithelium Term Ho are the primary sex cords formed? Definition Arrival of the germ cells stimulates coelomic epithelium to proliferate and grow into the mesenchyme. . As a result, the primary sex cords form. Term What occurs at the end of 6 weeks? Definition Gonad has a cortex and a medulla. Primary sex cords contain germ cells. Term Whe PGCs enter the GR, what happens if Female? If Male? Definition If female, PGCs undergo mitosis and differentiate into oogonia, enter meiosis by 5th month of gestation and then are arrested in the 1st meiotic prophase until puberty. If male, PGCs undergo a few mitotic divisions and remain dormant until puberty. They do NOT enter meiosis until after puberty. Term What determines gender? Definition SRY = Sex determining region of the Y chromosome, TDF = testis - determining factor , No Y chromosome = ovary Term What is SRY? Definition SRY = Sex determining region of the Y chromosome Term What is TDF? Definition TDF = testis - determining factor Term Where do you find the SRY gene? Definition Short arm of Y chromosome. FOund only in genital ridge Term What is SRY's function? Definition Functions as a transcription regulatory factor for other genes that determine maleness. SF-1 WT1 SOX9 DAX-1 Presence of SRY leads to male development. Term What does TDF do? Definition This gene transcribes proteins which produces male sex cords: Induces gonadal cords to condense and extend into the medulla of the indifferent gonad, i.e., form seminiferous cords. Term What happens with Female (XX) mouse with an SRY gene? Definition Study using transgenic 46,XX mice who had an SRY gene on the X chromosome produced an 46,XX mouse with testes and male external genitalia. Mouse is sterile. Term Is there a female equivalent of SRY? Definition Murine Wnt4 is required for development of the female repro tract AND suppression of the male repro tract. Term What is Wnt4? Definition Wnt4 is a growth factor involved in multiple developmental processes such as the formation of the kidney, adrenal, mammary gland, pituitary and the female reproductive system. During mammalian embryogenesis, Wnt4 is expressed in the gonads of both sexes before sex determination events take place and is subsequently down-regulated in the male gonad. Inactivation of the Wnt4 gene in mice has revealed that it is involved at several steps of female reproductive development. Wnt4 is implicated in Mullerian duct regression, the formation of sex-specific vasculature, the inhibition of steroidogenesis and in sex-specific cell migration events. A mouse model of sex-reversal has partially unravelled the molecular pathways in which Wnt4 operates during the development of the female reproductive system. However, the specific molecular mechanism of action of Wnt4 during gonadal development remains unknown. This and downstream signaling pathways involved in Wnt4 action during female gonad development are reviewed and models of Wnt4 action are proposed for Mullerian duct formation, sex-specific vasculature development, and sex determination events. Further identification of critical downstream effectors of the Wnt4 signaling pathway in mouse models and in patients with sex-reversal conditions could help in understanding sex-reversal pathologies in humans. Term If no SRY gene? Will you express Wnt4? Definition If NO sry, NO suppression of SF1, which allows for expression of Wnt4 Term If male, what will primary sex cord do? Definition TDF induces primary sex cords to condense and extend into medulla of an undifferentiated gonad where they will branch and form the rete testis (which are connections of sex cords). Finally, the connections of the cords will be lost when the Tunica Albuginea develops. Term What does SRY compete with? Definition SRY competes with the DAX1 protein to activate or repress the SF1 gene. If a single X and Y chromosome are present, the SRY will be favored, and the activation of SF1 will occur. If two copies of DAX1 are present on the X chromosome (or if there is no Y chromosome), the SF1 gene will not be activated. The SF1 protein is thought to activate the SOX9 gene, which instructs the sex cords to develop into the Sertoli cells of the testes, and may also repress WNT4. WNT4 would otherwise cause the differentiation of the gonad into an ovary. Most of the genes activated by WNT4 and SOX9 have not been identified, and the mechanisms by which SRY and DAX1 function are not yet known. Term List the sequence to testes development Definition 1. Primary sex cords condense and extend into the medulla of the developing gonad and become: a. Seminiferous cords b. Rete testis 2. Cords will separate from the cortex when Formation of tunica albuginea 3. Mesenchyme forms between the seminiferous cords Term What does the mesenchyme between the sex cords in males become? Definition Leydig cells secreting androgenic horomones Term What are the 2 main male horomones? Definition A. Androgenic hormones (testosterone, androstenedione) B. Mullerian inhibiting substance (MIS) = Antimullerian hormone (AMH) Term Which are the androgenic horomones? Definition Androgenic hormones (testosterone, androstenedione) Term What are Leydig cells? Definition Interstitial cells of Leydig (mesenchyme between seminiferous cords) Term What do androgenic horomone secretion result in? Definition Differentiation of the mesonephric ducts and external genitalia Term What does MIS result in? Definition Mullerian inhibiting substance (MIS) = Antimullerian hormone (AMH) Suppresses development of paramesonephric ducts Term Where does MIS get secreted from? Definition Sertoli cells (epithelial cells from cords) Term What makes up majority of Seminiferous cords? Definition sertoli cells Term What are the high points (summary) of testes development? Definition Seminiferous cords ( Sertoli cells, House spermatogonia, Rete testis) Formation of the tunica albuginea, Mesorchium – mesentery that suspends the testis, efferent ductules Term What houses spermatogonia? Definition Seminiferous cords House spermatogonia Term What is the mesorchium? Definition = Mesorchium – mesentery ligament that suspends the testis Term What is the rete testis? Definition extension of the seminif. chords, importnat for sperm production Term When are ovaries histologically identifiable? Definition not until week 10 Term What significance does the rete ovarii have? Definition none. it's a useless strucure. Term What do the primary gonadal cords become? Definition the rete ovarri. which has no function Term What do the secondary cords become? Definition Secondary cortical cords : 1. Surface epithelium outgrowths 2. Extend into mesenchyme 3. Incorporate primordial germ cells to form follicles. Term How are primary follicles formed? Definition Surface epithelium outgrowths, Extend into mesenchyme, Incorporate primordial germ cells to form follicles. Term What are primordial follicles? Definition Primordial follicles: Oogonium develops into an oocyte, Single layer of follicle cells – derived from the surface epithelium of the ovary. Term Are there any oogonia formed after birth? Definition NO! All oogonia formed by 5 months. Term Do oocytes go through programmed cell death? Definition Yes! infact, By 8 months gestation, 2/3 oocytes undergo programmed cell death. Term What do you have @ an indifferent stage? Definition 1. Gonads with primordial germ cells 2. Mesonephric ducts w/ uterovaginal primordium 3. Paramesonephric ducts Term When do Paramesenephric ducts degenerate? Definition Paramesenephric ducts degenerate (by 9-10 weeks) under the influence of MIS. Term What do the mesonephric ducts/glads become in males? Definition Mesonephric duct and tubules: 1. Efferent ductules 2. Ductus epididymis 3. Ductus deferens 4. Seminal gland (vesicle) 5. Ejaculatory duct – between seminal vesicle and urethra. Term What must be present for MND to develop? Definition Testosterone must be present for mesonephric duct structures to develop. Term Where does the prostate come from? What is it an outgrowth of? What does it grow into? Definition Prostate gland starts out as an endodermal outgrowth of the urethra. The endoderm grows into the surrounding mesenchyme to form the prostate gland. Term What are the other UG sinus derivates? Definition The other urogenital sinus derivatives are the bulbourethral glands = outgrowth of spongy urethra. Term what are the bulbourethal glands? Definition bulbourethral glands = outgrowth of spongy urethra. Term What are the 3 remnants of the PMNDucts? Definition 1. Appendix of the testis = vesicular attachment at superior pole of testis 2. Prostatic utricle = saclike structure that opens into prostatic urethra 3. Seminal colliculus = elevation in posterior wall of prostatic urethra Term Why are the PMNduct remnant structures important? Definition Important because these remants can become csytic and dilated.Sag Term What is the dual nature of fetal testicular horomone? Definition Dual nature of fetal testicular hormone: testosterone maintains the Wolffian ducts and virilizes the urogenital sinus and external genitalia via the androgen receptor; anti-Mullerian hormone (AMH) represses the development of Mullerian ducts, the anlagen of the female internal genital tract via the AMH receptor(s) Term Is Female development dependent on the presence of ovaries or female hormones? Definition Female development is NOT dependent on the presence of ovaries or female hormones!! Term What is an example of Female development NOT dependent on the presence of ovaries or female hormones? Definition Turner's Syndrome - 45, X (a little bit of ovarian tissue, but it still develops as a female) Term Why do Mesonephric ducts regress? Definition The mesonephric ducts regress because of the absence of testosterone. Term Why do PMN ducts persist? Definition The paramesonephric ducts persist because of the absence of MIS. Term What forms from PMN ducts? Definition Paramesonephric ducts form most of the female reproductive tract. Inferiorally, the PM ducts fuse = uterovaginal primordium Uterus, cervix, and upper (2/3) of the vagina Fusion of the PM ducts brings together a peritoneal fold that will form the broad ligament and create two peritoneal compartments. The uterine cavity is created by resorption after PM duct fusion. The unfused portion of the paramesonephric ducts form the fallopian tubes. Term What is a summary of female genital duct formation? Definition In the absence of AMH, the Müllerian ducts develop to form the Fallopian tubes, uterus, cervix and upper part of the vagina (Box 6.3). This differentiation begins around the 10th week of gestation and the Wolffian ducts begin to degenerate. Around the same time, the germ cells, that are now destined to become oogonia, enter their first meiotic division and are subsequently surrounded by a layer of granulosa cells to form primordial follicles. Such follicular development does not begin until about 15 weeks gestation (some 8 weeks later than the differentiation of the testes). At birth, each ovary contains about 2 million primordial follicles though this declines to about 200 000 primordial follicles by menarche. Each primordial follicle contains a primary oocyte half way through its first meiotic division. There is a vast over provision of potential oocytes and many become atretic well before the menopause. Thus, females are born with all the eggs they will ever have. This contrasts with the male germ cells or spermatogonia that, from puberty and throughout life, continue their ability to divide and to produce sperm. Term What does the fusion of the PM ducts create? Definition the uterovaginal primordium-- uterus, cervix, and the upper 2/3 of the vagina Term How do you form the broad ligament? Definition Fusion of the PM ducts brings together a peritoneal fold that will form the broad ligament and create two peritoneal compartments. Term How is the uterine cavity created? Definition The uterine cavity is created by resorption after PM duct fusion. Term What happens if no PM duct fusion? Definition 2 uterusi Term What does the unfused portion of the PMDucts become? Definition the fallopian tubes Term Where does the vagina come from ? Definition upper 2/3, from the uterovag primordium, from the PMNDucts, lower 1/3 comes from Contact of the uterovaginal primordium with the urogenital sinus results in formation of the sinovaginal bulbs. Term How do you form the vagina (ctd)? Definition Sinovaginal bulbs fuse in the midline to form the vaginal plate. Then, Central cells breakdown leads to the lumen of the vagina. Then the Hymen separates lumen of vagina from UG sinus In embryos of Carnegie stages 22 and 23, two Müllerian ducts made contact with each other and fused into a single tube. This fusion process appears to work as follows: First, the basement membranes of the two Müllerian ducts fuse with each other upon the disappearance of the basement membrane of each contact side. Second, the epithelial cells of the two Müllerian ducts are rearranged when the septum vanishes (see Figs. 4 and 8). Many clinicians and embryologists believe that the fused Müllerian ducts reach the urogenital sinus and invaginate into its wall to form the Müllerian tubercle. The bifurcation of the fused duct (uterovaginal canal) at the caudal portion at Carnegie stages 22 and 23 is a new finding. As shown in Figure 7, the caudal portion of the fused Müllerian duct separates again and returns to the respective Wolffian ducts. The caudal elongation of the uterovaginal canal arises from the lengthening of the Müllerian ducts. Since the Müllerian ducts have not yet reached the urogenital sinus in Carnegie stage 23, the Müllerian tubercle has not yet formed. There has never been a report of two Müllerian tubercles in a normal fetus; therefore, the caudal bifurcated uterovaginal canal that reaches the urogenital sinus forms one Müllerian tubercle. Term Name 3 Mullarian anomalies? Definition 1. Agenesis of one gonadal ridge  no PM duct 2. Abnormal fusion of the PM ducts 3. Incomplete canalization