Severson's normal genital development; 4.7 Flashcards Preview

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Flashcards in Severson's normal genital development; 4.7 Deck (41):
1

What forms the urogenital ridge?

Intermediate mesoderm

2

When does a fetus start developing specific genitalia?

7th week of development

3

What gene is necessary for male development?

SRY gene (Sex-determining Region of Y)

4

What is the SRY gene responsible for?

SRY gene → testis-determining factor → gonadal cords differentiate into seminiferous tubules

5

What is produced in fetal testes that determines maleness?

Testosterone

6

What is necessary for complete ovarian development?

XX genotype (and not having Y)

7

Is femaleness determined by hormonal influence?

No...but estrogen (produced by placenta and ovaries) → feminization of external genitalia

8

What are the contents of the gonads?

Mesothelium (coelomic epithelium)
Mesenchyme (underlying the mesothelium)
Primordial germ cells

9

Where do the primordial germ cells originate?

Primordial cells originate in the yolk sac

10

Where do the primordial germ cells migrate? When?

Along the dorsal mesentery of the hind gut to the gonadal ridges

Latter half of the 5th week

11

Where do the primordial germ cells go in males?

Migrate into the gonadal cords

12

Where do the primordial germ cells go in females?

Remain in underlying mesenchyme

13

What do the gonadal cords (w/ primordial germ cells) become?

Seminiferous tubules
Sertoli cells
Rete testis

14

Despite not maturing during the fetal period, Sertoli cells still contribute to development. What do they produce? What causes the secretion?

Sertoli cells produce anti-Mullerian hormone d/t hCG

15

What does anti-Mullerian hormone do?

Suppresses development of the paramesonephric (Mullerian) ducts

16

What do mesonephric tubules become?

Efferent ductules

17

What do efferent ductules do?

Efferent ductules connect to the mesonephric duct...which becomes the epididymis

18

What does the mesenchyme in the gonads become?

Cells of Leydig → synthesize androgenic hormones

19

What happens with primordial germ cells in ovaries?

Undergo mitosis → numerous oogonia

20

What causes oogonia to enter prophase I of meiosis?

Meiosis-stimulating factor

21

What are oogonia called after entering prophase I of meiosis?

Primary oocytes

22

What is needed for oogonia/oocytes to be considered primordial follicles?

Follicular cell association

23

How long do primordial follicles stay in prophase I?

Until a few days before ovulation

24

After ovulation, what phase of meiosis do secondary oocytes arrest in?

Metaphase II

25

How long do secondary oocytes remain in metaphase II?

Until fertilization

26

What are paramesonephric (Mullerian) ducts?

Coelomic epithelium along the mesonephric ridge...lateral to the mesonephric (Wolffian) ducts

27

What happens to the caudal ends of the Mullerian ducts?

Fuse and terminate on the urogenital sinus b/w the ends of the mesonephric ducts → uterovaginal primordium → sinus (Mullerian) tubercle

28

What happens to the cranial ends of the Mullerian ducts?

Open into the coelomic cavity

29

As said earlier, Sertoli cells produce anti-Mullerian hormone which causes the Mullerian ducts to degenerate. What remains of the Mullerian ducts in males?

Prostatic utricle
Appendix of of testis

30

As said earlier, Leydig cells produce testosterone. What is the result of testosterone action on mesonephric (Wolffian) ducts?

Wolffian ducts become the epididymis, ductus deferens, and ejaculatory duct

31

As said earlier, Leydig cells produce testosterone. What is the result of testosterone action on the ductus deferens?

Seminal vesicles develop

32

As said earlier, Leydig cells produce testosterone. What is the result of testosterone action on the urethra?

Formation of prostate and bulborurethral glands

33

What does the processus vaginalis become in males?

Tunica vaginalis

34

What does the gubernaculum become in females?

Ligament of the ovary and the round ligament of the uterus

35

What does the genital tubercle at the cranial end of the cloacal membrane become?

Genital tubercle → phallus

36

What does the phallus become?

Phallus + testosterone → penis
Phallus - testosterone → clitoris

37

The corpora cavernosa and corpus spongiosum of the penis are derived from what?

Mesenchyme of the phallus → corpora cavernosa and corpus spongiosum

38

What does fusion of urogenital folds form in males?

Spongy urethra is the inner cavity

Penile raphe is the line of fusion on the ventral surface

39

How does the rest of the urethra form (obviously just in males)?

The ectodermal cord grows in from the glans and connects to the spongy urethra

40

What happens to the urogenital folds in females?

Become the labia minora...do NOT fuse

41

What is the name of the space between the urogenital folds?

Vestibule