Severson's normal genital development; 4.7

Question 1

What forms the urogenital ridge?

Answer 1

Intermediate mesoderm

Question 2

When does a fetus start developing specific genitalia?

Answer 2

7th week of development

Question 3

What gene is necessary for male development?

Answer 3

SRY gene (Sex-determining Region of Y)

Question 4

What is the SRY gene responsible for?

Answer 4

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

Question 5

What is produced in fetal testes that determines maleness?

Answer 5

Testosterone

Question 6

What is necessary for complete ovarian development?

Answer 6

XX genotype (and not having Y)

Question 7

Is femaleness determined by hormonal influence?

Answer 7

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

Question 8

What are the contents of the gonads?

Answer 8

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

Question 9

Where do the primordial germ cells originate?

Answer 9

Primordial cells originate in the yolk sac

Question 10

Where do the primordial germ cells migrate? When?

Answer 10

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

Latter half of the 5th week

Question 11

Where do the primordial germ cells go in males?

Answer 11

Migrate into the gonadal cords

Question 12

Where do the primordial germ cells go in females?

Answer 12

Remain in underlying mesenchyme

Question 13

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

Answer 13

Seminiferous tubules
Sertoli cells
Rete testis

Question 14

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

Answer 14

Sertoli cells produce anti-Mullerian hormone d/t hCG

Question 15

What does anti-Mullerian hormone do?

Answer 15

Suppresses development of the paramesonephric (Mullerian) ducts

Question 16

What do mesonephric tubules become?

Answer 16

Efferent ductules

Question 17

What do efferent ductules do?

Answer 17

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

Question 18

What does the mesenchyme in the gonads become?

Answer 18

Cells of Leydig → synthesize androgenic hormones

Question 19

What happens with primordial germ cells in ovaries?

Answer 19

Undergo mitosis → numerous oogonia

Question 20

What causes oogonia to enter prophase I of meiosis?

Answer 20

Meiosis-stimulating factor

Question 21

What are oogonia called after entering prophase I of meiosis?

Answer 21

Primary oocytes

Question 22

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

Answer 22

Follicular cell association

Question 23

How long do primordial follicles stay in prophase I?

Answer 23

Until a few days before ovulation

Question 24

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

Answer 24

Metaphase II

Question 25

How long do secondary oocytes remain in metaphase II?

Answer 25

Until fertilization

Question 26

What are paramesonephric (Mullerian) ducts?

Answer 26

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

Question 27

What happens to the caudal ends of the Mullerian ducts?

Answer 27

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

Question 28

What happens to the cranial ends of the Mullerian ducts?

Answer 28

Open into the coelomic cavity

Question 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?

Answer 29

Prostatic utricle

Appendix of of testis

Question 30

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

Answer 30

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

Question 31

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

Answer 31

Seminal vesicles develop

Question 32

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

Answer 32

Formation of prostate and bulborurethral glands

Question 33

What does the processus vaginalis become in males?

Answer 33

Tunica vaginalis

Question 34

What does the gubernaculum become in females?

Answer 34

Ligament of the ovary and the round ligament of the uterus

Question 35

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

Answer 35

Genital tubercle → phallus

Question 36

What does the phallus become?

Answer 36

Phallus + testosterone → penis

Phallus - testosterone → clitoris

Question 37

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

Answer 37

Mesenchyme of the phallus → corpora cavernosa and corpus spongiosum

Question 38

What does fusion of urogenital folds form in males?

Answer 38

Spongy urethra is the inner cavity

Penile raphe is the line of fusion on the ventral surface

Question 39

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

Answer 39

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

Question 40

What happens to the urogenital folds in females?

Answer 40

Become the labia minora…do NOT fuse

Question 41

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

Answer 41

Vestibule