Lecture 33: Genital System Pt 1

Question 1

what directs overall gonadal development

Answer 1

genotype which directs external genitalia development

Question 2

what are the two phases of development of the reproductive system

Answer 2

1. embryonic development of sex organs

2. secondary sexual development (puberty)

Question 3

what develops during embryonic development of sex organs (3 things)

Answer 3

1. Gonads (testes and ovaries)
2. Genital ducts
3. Accessory glands

Question 4

from what layer do the organs of the reproductive system predominantly develop from

Answer 4

intermediate mesoderm

Question 5

what DOESNT develop from the intermediate mesoderm in the reproductive system

Answer 5

the primordial germ cells (precursors of spermatogonia and oogonia) are from the yolk sac which is endodermally derived

Question 6

what happens during week 5-7 of gonadal development

Answer 6

migration of germ cells from yolk sac (forms genital ridge) and the thickening on the medial side of the mesonephros
NOTE: the gonads of men and women look exactly the same at this stage!! (INDIFFERENT)

Question 7

when do germ cells start migrating and where do they migrate

Answer 7

start migrating in week four along dorsal mesentery

Question 8

when do the primordial germ cells get incorporated into the primary sex cords

Answer 8

week 6

Question 9

how is the gonadal ridge formed

Answer 9

proliferating epithelium and mesenchyme form half moons known as the gonadal ridge

Question 10

what is the gonad formed from

Answer 10

external cortex and internal medulla

Question 11

what does development of a male phenotype require

Answer 11

the short arm of a Y chromosome (contains SRY gene which produces Testis Determining Factor) which is what directs the development of the testes

Question 12

what does development of a physiologically typical female require

Answer 12

two X chromosomes

Question 13

absence of y chromosome leads to

Answer 13

ovaries

Question 14

what doe the primary sex cords become in men

Answer 14

seminiferous cords, tubules and rete testes

Question 15

what does primary female sexual differentiation NOT depend on

Answer 15

female hormones (more important is the lack of testosterone)

Question 16

testes secrete

Answer 16

testosterone which leads to male differentiation

Question 17

how does the type of gonad come to differ

Answer 17

differentiation within genital ducts and external genitalia

Question 18

how do rete testes develop

Answer 18

from branching and anastemoses of sex cords

Question 19

what is the tunica albuginea

Answer 19

thick capsuel separating sex cords from surface epithelium; diagnostic of testicular development in a fetus.

Question 20

what is the mesorchium

Answer 20

what seperates the enlarging testes from the degenerating mesonephros (it is a mesentery)

Question 21

what gives rise to the cells of leydig

Answer 21

seminiferous tubules become seperated by a mesenchyme that gives rise to these interstitial cells

Question 22

when do interstitial cells of leydig arise

Answer 22

week 8

Question 23

what do interstitial cells of leydig secrete (when do they start)

Answer 23

testosterone and androstenedione – week 8

*this is masculine differentiation of mesonephric ducts and external genitalia – from mesonephric ducts

Question 24

where are sertoli cells and what do they secrete

Answer 24

secrete antimullerian hormone (AMH) and they are in the testes

Question 25

what is the function of AMH

Answer 25

supresses development of mullerian (paramesonephric) ducts through puberty

Question 26

what kind of cells are in the seminiferous tubules

Answer 26

2 types 1) sertoli 2) spermatogonia (primordial sperm cells derived from primordial germ cells)

Question 27

decribe the seminiferous tubules until puberty

Answer 27

solid

Question 28

describe the formation of the ductus epididymis

Answer 28

rete testis become continuous with 12-20 efferent ductules which are connected to the mesonephric duct which becomes the ductus epididymis

Question 29

what is required for the development of ovaries

Answer 29

x chromosome and autosome

Question 30

what happens to the primary sex cords in women

Answer 30

they degenerate along with the rete ovarii

Question 31

what gives rise to the cortical cords in women

Answer 31

the secondary sex cords -- cortical cords increase in size and primordial germ cells get incoporated into them

Question 32

what do primordial follicles consist of

Answer 32

oogonium and follicular follicles derived from sex cord

Question 33

when are all oogonia formed by

Answer 33

birth (about 2 million)

Question 34

at the indifferent stage (5-6 weeks) what kind of ducts are present`

Answer 34

mesonephric (wollfian) ducts which drained urine from mesonephric kidneys paramesonephric (mullerian) ducts

Question 35

what do mesonephric ducts become

Answer 35

proximal: convolutes to form epididymis lateral: seminal vesicles remainder: ductus deferens and ejaculatory duct

Question 36

where is the ejaculatory duct

Answer 36

the part of the mesonephric duct between seminal vesicle and urethra

Question 37

what is the function of the seminal vesicles

Answer 37

produces fluid that nourishes sperm and also makes vagina more alkaline for motility

Question 38

how does the prostate develop

Answer 38

endodermal outgrowths of prostatic urethra and surrounding mesenchyme

Question 39

what is the function of the prostate

Answer 39

produces fluid for semen -- sperm transport (in the first part of ejaculate)

Question 40

what are the bulbourethral glands formed from

Answer 40

outgrowths of spongy urethra

Question 41

what do the bulbourethral glands do

Answer 41

secretions contribute to semen

Question 42

what causes the mesopnephric ducts to regress in women

Answer 42

no testosterone

Question 43

what does no MIS cause in women

Answer 43

paramesonephric ducts develop

Question 44

what forms the paramesonephric ducts

Answer 44

WOMEN!!! invaginations on lateral mesonephrons approach and fuse, creating ducts

Question 45

where do the paramesonephric ducts pass

Answer 45

caudally into the pelvic region. they develop lateral to gonads and mesonephric ducts

Question 46

what is the uterovaginal primordium

Answer 46

meeting of paramesonephric ducts in the pelvic region (y shaped)

Question 47

what does the paramesonephric duct become

Answer 47

the fallopian tubes (unfused part before the uterovaginal primordium)

Question 48

what does the uterovaginal primordium become

Answer 48

the vagina and uterus

Question 49

what is the mulleriuan (sinus) tubercule

Answer 49

projection of uterovaginal primordium into urogenital sinus

Question 50

what causes the formation of the broad ligament

Answer 50

the fusion of the paramesonephric ducts brings together 2 peritoneal folds that form the broad ligament

Question 51

what causes the formation of the vaginal plate

Answer 51

uterovaginal primordium meets urogenital sinus forms sinus tubercule which induces formation of paired endodermal outgrowths (sinovaginal bulbs). these bulbs fuse to form the vaginal plate

Question 52

how does the vaginal plate become the vagina

Answer 52

central cells break down and you get a lumen.

Question 53

what separates the lumen from the cavity of the urogenital sinus

Answer 53

the hymen

Question 54

what forms Skene's glands

Answer 54

buds from urethra form urethral and skenes (paraurethral)

Question 55

what forms bartholin's glands

Answer 55

buds from urogenital sinus

Question 56

homologous auxillary genital glands from urethra

Answer 56

women: urethral and paraurethral glands men: prostrate

Question 57

homologous auxillary genital glands from urogenital sinus

Answer 57

women: greater vestibular glands of bartholin men: bulbourethral glands