1 - G Embryology Of Male/female Reproductive Systems

Front 1

Where does urogenital system derive from?

Back 1

Common ridge of intermediate mesoderm that lies in POSTERIOR ABDOMINAL WALL.

Front 2

Up until what point of gestation are the MALE AND FEMALE SYSTEMS IDENTICAL?

Back 2

up until 7 weeks

Front 3

How is blood exchanged in the placenta?

Back 3

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.

Front 4

What is the intermediate mesoderm?

Back 4

Embryologic organ that develops into cloaca, KIDNEYS, and gonads, mesonephros, meso and parameso -nephric ducts

Front 5

What is the mesonephros?

Back 5

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

Front 6

What is the mesonephric duct (Wollfian duct)?

Back 6

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.

Front 7

What is the paramesonephric duct (Mullerian ducts)?

Back 7

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.

Front 8

What is the cloaca attached to?

What does the cloaca differentiate into?

Back 8

Allantois (waste) and hindgut.

Anorectal canal. Urogential canal.

Front 9

Where do Primordial Germ Cells originate?

Where do PGC's migrate to?

Back 9

Yolk sac endoderm.

Gonadal ridge (via hindgut)

Front 10

Where is the gonadal ridge located? When does it appear?

What does the gonadal ridge give rise to?

Back 10

It is in mesothelium (coelemic epithelium).

it appears around 5 wks gestation.

Gives rise to SEX CORDS.

Front 11

What happens to coloemic epithelium of mesothelium (gonadal ridge) UPON ARRIVAL OF PGC's?

Back 11

Coelomic epithelium begins to proliferate INTO UNDERLYING mesenchyme.

Front 12

Where do SEX CORDS come from?

What do they become?

Back 12

SEX CORDS arise from proliferating mesothelium in the gonadal ridge.

They will become the seminiferous/testes cords (NOT TUBULES). They support/nourish Sertoli cells.

Front 13

Where are PGC's contained in gonadal ridge?

Back 13

In SEX CORDS.

Front 14

What happens to PGC's for EACH sex upon arrival to gonadal ridge?

Back 14

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.

Front 15

How many oogonia does female have upon birth?

Back 15

NONE! All eggs should be at primary prophase by birth. At 5th month of gestation, oogonia meoisis into primary oocytes.

Front 16

What is SRY?

Where is SRY expressed?

Back 16

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.

GONADAL RIDGE!

Front 17

What is TDF?

Back 17

Testis-determining factor. ENCODED IN SRY.

It induces gonadal cords to condense and form seminiferous tubules.

Front 18

What is the female equivalent of SRY?

Back 18

WNT-4. WNT-4 is required for growth of female reproductive tract AND SUPRESSION of male repro tract.

Front 19

How does SRY suppress WNT-4?

Back 19

SRY activates SF1, which both INHIBITS WNT-4, but also ACTIVATES SOX-9. Sox-9 triggers tests development

Front 20

What suppresses SF1

Back 20

SF1, which inhibits WNT-4 and SOX9 in developing males, is itself INHIBITED BY DAX-1.

Dax-1 is found on the X-chromosome.

Front 21

Where do seminiferous cords come from and what do they become?

Back 21

Seminiferous cords come from sex cords, which comes from gonadal ridge and coelomic epithelium.

They will BECOME the rete testis and house spermatogonia.

Front 22

What is located IN BETWEEN seminiferous cords?

Back 22

Mesenchyme which contains TESTOSTERONE-producing Leydig cells.

Front 23

What does testosterone do?

Back 23

Testosterone triggers mesonephric duct differentiation and that of external genitalia.

Front 24

What are Sertoli cells?

Back 24

They are found adjacent to spermatogenesis cells.

They are the epithelial cells of the seminiferous tubules.

They secrete AMH and suppress paramesophric development.

Front 25

At how many weeks are ovaries identifiable?

Back 25

At 10 weeks should be histologically identifiable.

Front 26

What is the function of PRIMARY AND SECONDARY SEX CORDS in ovary?

Back 26

Primary sex cords - Not present.

Primitive sex cords become secondary sex cords - Surface epithelium grows. Extension into mesenchyme. INCORPORATE GERM CELLS TO FORM FOLLICLES.

Front 27

How are follicles created?

Back 27

Via the incorporation of germ cells with secondary sex cords (cortical cords)

Front 28

At what point is a woman's number of eggs at its HIGHEST PEAK?

Back 28

by 20 weeks gestation. ~6-7 oogonia.

Front 29

What percentage of eggs have undergone programmed atresia by near birth?

Back 29

2/3 undergo atresia.

Front 30

Where do para and meso -nephric ducts come from?

Back 30

They come from mesonephros, which comes from intermediate mesoderm.

Front 31

What hormone is NECESSARY for mesonephric duct differentiation?

Back 31

TESTOSTERONE from Leydig cells.

Front 32

What are two urogenital sinus derivatives?

Back 32

Prostate gland (endodermal outgrown of urethra) AND bulbourethral glands.

Front 33

TRUE / FALSE:

Female development IS DEPENDENT on ovary or female hormones?

Back 33

FALSE!!!

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

No mesonephric development because no testosterone to stimulate.

Front 34

Where is BROAD LIGAMENT of UTERUS from?

Back 34

It is from paramesonephric system.

Front 35

What is the role of the hymen?

Back 35

To separate the vaginal lumen from the UG sinus

Front 36

What is the uterovaginal primordium?

Back 36

It is formed when BOTH PARAMESONEPHRIC DUCTS fuse.

Fusion of PD's creates broad ligament. Unfused portion of PD creates fallopian tubes.

Front 37

How does UV primordium trigger vaginal plate formation?

Back 37

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.