Development Of The Reproductive System

Front 1

how do the gonads first appear?

Back 1

genital ridges: a pair of longitudinal ridges that bulge into the coelom.

Front 2

what types of mesoderm are the genital ridges?

Back 2

intermediate mesoderm and splanchnic mesoderm.

Front 3

where do primordial germ cells originate?

Back 3

the yolk sac

Front 4

where do the primordial germ cells migrate and populate?

Back 4

genital ridges

Front 5

how do the primitive sex cords form?

Back 5

epithelium of the genital ridge proliferates and invades the underlying mesenchyme.

Front 6

what does "indifferent gonad" mean?

Back 6

the male and female gonads initially look identical

Front 7

describe testis development from sex cords to production of testosterone

Back 7

primitive sex cords form testis cords. testis cords cavitate to form the seminiferous tubules and rete testis. Interstitial cells (of Leydig) form from intermediate mesoderml, and produce testosterone by week 8.

Front 8

what type of mesoderm do interstitial cells derive from?

Back 8

intermediate mesoderm

Front 9

what forms the vas deferens and epididymis?

Back 9

mesonephric (Wolffian) duct

Front 10

what form the efferent ductules of the testis?

Back 10

mesonephric tubules

Front 11

how do the prostate and bulbourethral glands form?

Back 11

expand from the endoderm of the urogenital sinus.

Front 12

how do the seminal vesicles form?

Back 12

branch from the mesonephric ducts

Front 13

describe ovary development until formation of follicular cells.

Back 13

-primitive sex cords turn into irregular cell clusters.
-epithelium gives rise to a second generation of sex cords: the cortical cords.
-cortical cords split into isolated cell clusters that surround the primordial germ cells and form follicular cells.

Front 14

what happens to the mesonephric ducts and tubules in females?

Back 14

they largely degenerate.

Front 15

what are the 3 remnants of the mesonephric ducts and tubules?

Back 15

epoophoron, paroophoron, and gartner's cysts.

Front 16

does the paramesonephric (Mullerian) duct initially form in both males and females?

Back 16

yes

Front 17

where does the paramesonephric (Mullerian) duct form?

Back 17

ventrolateral surface of the urogenital ridge

Front 18

describe the Mullerian ducts cranially and caudally

Back 18

cranially they are open, caudally they run to the midline, fuse, and project into the dorsal wall of the UG sinus.

Front 19

what happens to the paramesonephric (Mullerian) ducts in the female?

Back 19

cranially they become the uterine tubes. Caudally they fuse to form the uterovaginal canal.

Front 20

what forms at the junction of the paramesonephric ducts in the female?

Back 20

paramesonephric tubercle

Front 21

what happens to the paramesonephric tubercle?

Back 21

extends as a solid vaginal plate towards the uterovaginal canal. the plate cavitates to form the vaginal lumen.

Front 22

what happens to the paramesonephric ducts in the male?

Back 22

testes secrete anti-Mullerian hormone, which causes the degeneration of the ducts.

Front 23

what remains of the paramesonephric ducts in the male?

Back 23

at the cranial end: appendix testes.
at the caudal end: prostatic utricle.

Front 24

describe development of the indifferent stage of the external genitalia

Back 24

mesenchyme lateral to the cloaca proliferates to form the cloacal folds. the folds unite cranially to become the genital tubercle. caudally the folds subdivide to form the urogenital folds and the anal folds. genital swellings form lateral to the urethral folds.

Front 25

how is the urethral fold formed?

Back 25

the urogenital membrane breaks down to form the urethral fold.

Front 26

what is development of the external genitalia dependent on?

Back 26

testosterone

Front 27

describe development of male external genitalia from end of indifferent stage to urethral fold closing.

Back 27

the genital tubercle elongates and pulls the urethral plate and folds with it. the urethral folds close over the urethral plate, thereby enclosing the penile urethra.

Front 28

describe development at tip of the penis

Back 28

ectodermal cells from tip invaginate and form a short ectodermal cord. the chord meets with the spongy (penile) urethra, and cavitates to complete the penile urethra.

Front 29

what are hypospadias?

Back 29

abnormal position of penile urethra.

Front 30

what 2 things can cause a hypospadia?

Back 30

1. failure of canalization of ectodermal cord.
2. failure of fusion of the urethral folds.

Front 31

describe how scrotum forms from indifferent stage of external genitalia.

Back 31

scrotal swellings move caudally and fuse. the two halves remain separate internally.

Front 32

where does the gubernaculum grow into?

Back 32

grows into the scrotal swellings.

Front 33

what happens to the parietal peritoneum during the descent of the testes? what does it form?

Back 33

it forms an evagination into the ventral abdominal wall: vaginal process.

Front 34

what is cryptorchidism?

Back 34

failure of testes to descend.

Front 35

what does the vaginal process eventually form?

Back 35

forms the scrotal cavity with parietal and visceral layers of serosa.

Front 36

what can a patent vaginal process cause?

Back 36

partial or complete herniation of the intestines into the spermatic chord or scrotum

Front 37

what is a hydrocele?

Back 37

coelomic fluid can remain trapped in scrotum after vaginal process obliterates.

Front 38

describe development of external genitalia in females after indifferent stage.

Back 38

genital tubercle elongates slightly to form clitoris. urethral folds don't fuse, but form the labia minora. genital swellings enlarge and form the labia majora.

Front 39

what largely causes uterine defects?

Back 39

failed fusion of the paramesonephric ducts.