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37 Cards in this Set

  • Front
  • Back
Where does urogenital system derive from?
Common ridge of intermediate mesoderm that lies in POSTERIOR ABDOMINAL WALL.
Up until what point of gestation are the MALE AND FEMALE SYSTEMS IDENTICAL?
up until 7 weeks
How is blood exchanged in the placenta?
Chorionic villi grow into placenta containing small fetal arteries and veins.

Maternal blood enters via lacunae into INTERVILLOUS SPACE.

Fetal/maternal blood do not mix, but come very close.
What is the intermediate mesoderm?
Embryologic organ that develops into cloaca, KIDNEYS, and gonads, mesonephros, meso and parameso -nephric ducts
What is the mesonephros?
It is one of three excretory bodies in embryo. It also acts as a temporary kidney. Connects with allantois to form cloaca.

Derived from intermediate mesoderm. Becomes efferent tubules of testes, epididymis, vas deferens, seminal vesicles
What is the mesonephric duct (Wollfian duct)?
It connects the mesonephros to the cloca.

In men, it is stimulated by testosterone and develops into the rete testes, efferent tubules of testes, vas deferens, seminal vesicle, and prostate.

Its function is to STORE AND MATURE sperm.
What is the paramesonephric duct (Mullerian ducts)?
Embryonic ducts that connect to cloaca.

Mullerian ducts will grow in ABSENCE of AMH (anti-mullerian hormone). Tests produce AMH.

Paramesonephric ducts originate from intermediate mesoderm.

Will become upper 2/3 of vagina, cervix, uterus, and fallopian tubes.
What is the cloaca attached to?

What does the cloaca differentiate into?
Allantois (waste) and hindgut.

Anorectal canal. Urogential canal.
Where do Primordial Germ Cells originate?

Where do PGC's migrate to?
Yolk sac endoderm.

Gonadal ridge (via hindgut)
Where is the gonadal ridge located? When does it appear?

What does the gonadal ridge give rise to?
It is in mesothelium (coelemic epithelium).

it appears around 5 wks gestation.

Gives rise to SEX CORDS.
What happens to coloemic epithelium of mesothelium (gonadal ridge) UPON ARRIVAL OF PGC's?
Coelomic epithelium begins to proliferate INTO UNDERLYING mesenchyme.
Where do SEX CORDS come from?

What do they become?
SEX CORDS arise from proliferating mesothelium in the gonadal ridge.

They will become the seminiferous/testes cords (NOT TUBULES). They support/nourish Sertoli cells.
Where are PGC's contained in gonadal ridge?
What happens to PGC's for EACH sex upon arrival to gonadal ridge?
PGC for women.

Women --> PGC's undergo mitosis and differentiate into PRIMARY OOGONIA. Enter meiosis by 5TH GESTATIONAL MONTH. Then arrest in PROPHASE I until puberty.

In MEN, PGC's undergo a FEW MITOTIC DIVISIONS and remain dormant until Puberty. MEIOSIS IN MEN NOT UNTIL AFTER PUBERTY.
How many oogonia does female have upon birth?
NONE! All eggs should be at primary prophase by birth. At 5th month of gestation, oogonia meoisis into primary oocytes.
What is SRY?

Where is SRY expressed?
SRY is region found on short arm of Y chromosome as Sex-determining region.

Without SRY, NO MALE. X chromosomes with SRY develop into men.

What is TDF?
Testis-determining factor. ENCODED IN SRY.

It induces gonadal cords to condense and form seminiferous tubules.
What is the female equivalent of SRY?
WNT-4. WNT-4 is required for growth of female reproductive tract AND SUPRESSION of male repro tract.
How does SRY suppress WNT-4?
SRY activates SF1, which both INHIBITS WNT-4, but also ACTIVATES SOX-9. Sox-9 triggers tests development
What suppresses SF1
SF1, which inhibits WNT-4 and SOX9 in developing males, is itself INHIBITED BY DAX-1.

Dax-1 is found on the X-chromosome.
Where do seminiferous cords come from and what do they become?
Seminiferous cords come from sex cords, which comes from gonadal ridge and coelomic epithelium.

They will BECOME the rete testis and house spermatogonia.
What is located IN BETWEEN seminiferous cords?
Mesenchyme which contains TESTOSTERONE-producing Leydig cells.
What does testosterone do?
Testosterone triggers mesonephric duct differentiation and that of external genitalia.
What are Sertoli cells?
They are found adjacent to spermatogenesis cells.

They are the epithelial cells of the seminiferous tubules.

They secrete AMH and suppress paramesophric development.
At how many weeks are ovaries identifiable?
At 10 weeks should be histologically identifiable.
What is the function of PRIMARY AND SECONDARY SEX CORDS in ovary?
Primary sex cords - Not present.

Primitive sex cords become secondary sex cords - Surface epithelium grows. Extension into mesenchyme. INCORPORATE GERM CELLS TO FORM FOLLICLES.
How are follicles created?
Via the incorporation of germ cells with secondary sex cords (cortical cords)
At what point is a woman's number of eggs at its HIGHEST PEAK?
by 20 weeks gestation. ~6-7 oogonia.
What percentage of eggs have undergone programmed atresia by near birth?
2/3 undergo atresia.
Where do para and meso -nephric ducts come from?
They come from mesonephros, which comes from intermediate mesoderm.
What hormone is NECESSARY for mesonephric duct differentiation?
TESTOSTERONE from Leydig cells.
What are two urogenital sinus derivatives?
Prostate gland (endodermal outgrown of urethra) AND bulbourethral glands.

Female development IS DEPENDENT on ovary or female hormones?

Paramesonephric system persists because of absence of MIS (AMH).

No mesonephric development because no testosterone to stimulate.
It is from paramesonephric system.
What is the role of the hymen?
To separate the vaginal lumen from the UG sinus
What is the uterovaginal primordium?
It is formed when BOTH PARAMESONEPHRIC DUCTS fuse.

Fusion of PD's creates broad ligament. Unfused portion of PD creates fallopian tubes.
How does UV primordium trigger vaginal plate formation?
UV promordium fuses with urogenital sinus to form sinovaginal bulbs.

Sinovaginal bulbs fuse in the midline to form vaginal plates.

Central cells break down and form vaginal lumen.