Development of the Reproductive System (Exam 2) Flashcards
When does the development of the reproductive system begin
5th week of gestation
What are the 4 stages of development of the reproductive system
Development of sexually indifferent gonads
Development of ovary/testis
Development of gonadal ducts
Development of the external genitalia
What does the intermediate mesoderm give rise to
Urogenital system
What is the urogenital ridge derived from
intermediate mesoderm
Where is the urogenital ridge found
cranial to caudal regions of the embryo lateral to somites
What are the two components of the urogenital ridge
Nephrogenic cord
Gonadal ridge
What does the nephrogenic cord give rise to
urinary system
What does the gonadal ridge give rise to
genital system
In relation to the nephrogenic cord, where is the gonadal ridge
ventral and inferior
Where is the gonadal ridge found
posterior body wall
When and where does the sexually indifferent gonad begin to develop
along the dorsal body wall during week 5
What are the outcomes of the sexually indifferent gonad
formation of gonadal ridge
migration of primordial germ cells to the ridge
primitive sex cord formation from primordial germ cells
What are the 3 sources from which gonads are derived from
mesenchyme
coelemic epithelium
germ cells
What do primordial germ cells contribute to the genital system
spermatogonia and oocytes
How do primordial germ cells migrate to the gonadal ridge
dorsal mesentery
When will primordial germ cells invade the gonadal ridge
during the 6th week
How are the primitive sex cords formed
proliferation of epithelial cells into the underlying mesenchyme
What will the cortex and medulla of the gonadal ridge differentiate into in males and females
females: cortex is the ovary
males: medulla is the testes
When and where will the sexually different gonad begin to form
along the dorsal body wall beginning week 7
What are the outcomes of the gonad
testis and ovary
What induces male gonadal development
Testis dermining factor
What gene is responsible for the production of TDF
SRY gene
What does SRY gene stand for
sex determining region of Y chromosome
How will TDF affect gonadal cords
TDF causes gonadal cords to condense and extend into the medulla of the gonad to form seminiferous cords
When will gonadal cords lose connection to the epithelium
when the tunica albuginea forms
What will the seminiferous cords develop into
seminiferous tubules
rete tesis
tubuli recti
How will TDF affect surface epithelium
causes it to thick and form tunica albuginea and primitive sex cords to form rete testes
How are rete testes formed
seminiferous cord under the influence of TDF condenses and branches into rete testes
How are Leydig cells formed
seminiferous tubules are separated by mesenchyme that give rise to interstitial cells
When will Leydig cells start secreting hormone
10th week
What are sertoli cells derived from
epithelium
What do Sertoli cells secrete
Mullerian inhibiting factor
What are sertoli cells
supporting cells
What gives rise to Leydig cells
Mesenchymal cells
What do Leydig cells secrete
Testosterone
When do Leydig cells start secreting Testosterone
week 8
What induces female gonad development
No TDF
What hormones are required for primary female sexual differentiation
none
When will the ovary be visible
around week 10
What gives rise to cortical cords
proliferation of epithelium
Where do cortical cords extend in the female
epithelium of the developing ovary into the mesenchyme
As cortical cords grow in size, what occurs
primordial germ cells are incorporated
When and how are primordial follicles formed
cortical cords break into clusters around primordial germ cells at week 16
What do primordial follicles consist of
oogonium
What surrounds priordial follicles
follicular cells
How does the surface of the ovary change after birth
flattens to a single layer that is continuous with mesothelium of peritoneum and epithelium is separated from the follicle by the tunica albuginea
What will result from the cortical cord breaking up in females
primordial follicles
How will testes descend
guided by gubernaculum and descend due to differential growth
What genital ducts will persist in males
mesonephric duct
What genital duct will persist in females
paramesonephric duct
How will testosterone affect ducts in males
allow mesonephric duct to continue
What stimulates testosterone production in males
human chorionic gonadotropin
What causes paramesonephric ducts to arrest in males
MIF from sertoli cells
Where are the paramesonephric ducts found
behind genital region, anterior and lateral to mesonephric duct
What will mesonephric ducts form in males
epididymis
ductus deferens
ejaculatory duct
Where do rete testis drain
efferent ductules into mesonephric duct
What are remnants of the paramesonephric duct in males
appendix of testis
prostatic utricle
What are the derivatives of the UG sinus in males
prostate and bulbourethral glands
What is the gonad of the male genital system
testis
What is the primordial germ cell of the male genital system
spermatogonia
What is the primary sex cord of the male genital system
seminiferous cords
What is the seminiferous cord give rise to in the male genital system
seminiferous tubules
rete testis
tubuli rect
What does the mesonephric tubules give rise to in the male genital system
efferent ductules
What does the mesonephric ducts give rise to in the male genital system
epididymis
vas deferens
ejaculatory duct
seminal vesicles
What duct will regresss in females
mesonephric duct
Why does the mesonephric duct regress in females
no testosterone
What duct will persist in females
paramesonephric duct
Why does the paramesonephric duct persist in females
no MIF
What occurs to the paramesonephric duct in the absence of MIF
enlarge and fuse on caudal end
How is the broad ligament of the uterus formed
paramesonephric duct grows anterior and medial and pulls with it a fold of peritoneum
What pouches are formed from the broad ligament
rectovesical posteriorly and uterovesical anteriorly
How are the uterine tubes, formed
uterine tubes develop from unfused parts of the cranial paramesonephric ducts
How are the uterus and vagina superiorly formed
caudal fused portions form the uterovaginal primordium which gives rise to uterus and superior vagina
How will urethral and paraurethral glands develop in females
buds from the surrounding urethra into the mesenchyme
What do greater vestibular glands in females develop from
outgrowths of UG sinus
How is the lumen of the vagina formed
fusion of UG sinus and UV primordium induces growth of sinovaginal bulbs to form a plate that breaks down later
What does the hymen separate
vagina from the UG sinus
What is a Gardner’s cyst
cyst in the remnant of the mesonephric duct
What are the remnants of the mesonephric duct
Gartners cyst
parapoophoron and epoophorons
What structures form the vagina
paramesonephric duct
UG sinus
What is the gonad of the female genital system
ovaries
What are the primitive sex cords of teh female genital system
degenerate
What are the primordial germ cells of the female genital system
oocyte
What are the mesonephric ducts of teh female genital system
degenerate
What are the paramesonephric ducts of the female genital system
uterine tubes
uterus
superior vagina
What are the cortical cords of the female genital system
primordial follicles and follicular cells
What is the UG sinus of the female genital system
inferior vagina, greater vestibular glands
What causes double/bicornate uterus
paramesonephric ducts never fused properly
What are possible uterine defects from failure of paramesonephric ducts to fuse
double uterus
bicornate uterus
uterus arcuatus
What causes double uterus
failure of fusion of the inferior parts of the paramesonephric ducts
What causes bicornate uterus
duplication only involves superior part of uterus
What causes uterus arcuatus
develops when one paramesonephric duct does not develop
When do distinguishing sexual characteristics begin to appear
week 9
When are sex characteristics fully differentiated
week 12
When do the external genitalia develop
weeks 9-12
What are the key outcomes of external genitalia formatiion
penis/scrotum
clitoris/labia majora
What will the cloacal folds become once the cloaca is partitioned
urethral folds
When will the genital tubercle form
4th week
How does the genital tubercle form
from mesenchyme
What is the primordial phallus
elongation of the genital tubercle
What does the fusion of the urorectal septum with the cloacal membrane form
dorsal anal membrane and ventral urogenital membrane
What hormone is necessary for male genitalia development
testosterone
How is the penis formed
primordial phallus enlarges and elongates to form penis
How is the spongy urethra formed
urethral folds fuse and is covered in ectoderm
How is the glans of the penis formed
ectodermal ingrowth
What do the corpus cavernosa and corpus spongiosum develop from
mesenchyme in the phallus
How is the scrotum formed
labioscrotal swellings fuse to form scrotum
What is hypospadias
fusion of the urethral folds are incomplete
What are the 4 types of hypospadias
glanular
penile
penoscrotal
perineal
How is the external urethral opening formed
epithelial cord lined with endoderm that then recanalizes
How is the clitoris formed
primordial phallus decreases in size
How is the frenulum formed
urogenital folds fuse posteriorly to form frenulum
How is the labia minor formed
unfused portion of urogenital folds
What will be formed by the anterior and posterior fusing of the labioscrotal folds
posterior and anterior labial commissure
What will be formed from posterior fusion of the urethral folds
frenulum of labia minora
What forms the labia majora
unfused portions of the labioscrotal swellings
How is the mons pubis formed
labioscrotal swellings fusing anteriorly
What is Turner’s Syndrome
chromosomal anomaly (46 X0)
What occurs to the genitalia in Turner’s syndrome
germ cells degenerate after reaching gonadal ridge; ovaries do not form, but rather “ovarian” streaks; external genitalia are female
What are hermaphrodites
intersex, discrepancy between the morphology of the gonads and the appearance of the external genitalia
What are the 3 types of hermaphrodites
True
Male
Female
What is True hermaphrodite
both testicular and ovarian tissue. External genitalia are ambiguous
What is the chromosome make up for most true hermaphrodites
70% 46, XX
What is male hermaphrodite
internal and external morphology varies on the development of the paramesonephric ducts.
What are the defects of a male hermaphrodite caused by
inadequate production of testosterone and MIF
What is the genetic make up of male hermaphrodite
46, XY
What is a female hermaphrodite
exposure of a female fetus to excessive levels of androgens
What is the most common outcome of a female hermaphrodite
masculinization of the external genitalia
What is the most common cause of female hermaphrodit
congenital adrenal hyperplasia
What is the genetic make up of a female hermaphrodite
46, XX
What is the genetic make up of Klinefelter syndrome
47, XXY
What is Klinefelter syndrome
males have small testes, tall stature, long lower limbs, gynecomastia, intelligence effected
What is Androgen Insensitivity Syndrome
46, XY appear as normal females
What are the results of androgen insensitivity syndrome
vagina ends in a blind pouch
uterine tubes absent or rudimentary
testes in abdomen
What causes androgen insensitivity syndrome
resistance to the action of testosterone due to a defect in the androgen receptor
What is a hydrocele
processus vaginalis doesn’t close and fluid accumulates
What is cryptochidism
undescended testes
What is congeintal (indirect) inguinal hernia
intestinal loops protrude through a persistent processus vaginalis
What is epispadias
external urethral opening is on the dorsal aspect of the penis
