Genital Embryology B&B Flashcards
what must happen during the embryological period for the development of the gonads to begin?
germ cells (derived from epiblast) must invade the gonadal ridges (derived from mesenchyme)
failure to reach gonadal ridges = failure for gonads to develop
the _____ gene (Y chromosome) codes for testis determining factor, which forms ____ and ____ cells
the SRY gene (Y chromosome) codes for testis determining factor, which forms SERTOLI and LEYDIG cells
Leydig cells produce testosterone —> medullary (testis) cords form
in female embryos, the medullary (testis) cords regress and the ______ develop to form clusters
cortical cords - form clusters which surround germ cells —> oogonia and follicular cells form primordial follicles
from what are the male vs female internal genitalia derived?
male - mesonephric (wolffian) duct
female - paramesonephric (mullerian) duct
these will form the internal genitalia that “hook up” to the gonads
[named for their relation to the mesonephros, the interim kidney in the 1st trimester]
how do Sertoli and Leydig cells both contribute to the development of male, rather than female, genital ducts?
Sertoli cells - secrete Mullerian inhibitory factor (MIF), which suppresses development of paramesonephric ducts [remnant remains as appendix testis]
Leydig cells - secrete androgens (testosterone) which stimulates development of mesonephric (wolffian) ducts
what is the function of the epididymis vs ductus deferens (vas deferens)
epididymis - transports sperm from the seminiferous tubules to vas deferens
ductus (vas) deferens: transports sperm from the epididymis to ejaculatory ducts
transports sperm from the seminiferous tubules to vas deferens
epididymis
transports sperm from the epididymis to ejaculatory ducts
ductus (vas) deferens
what is the function of the seminal vesicles, and where are they found?
glands behind the bladder, secrete ~75% of fluid in semen (remainder from prostate)
connects with ejaculatory ducts
Gartner’s Duct
Wolffian/mesonephric remnant in females
found on vaginal walls, may form painful cyst
the embryological cloaca divides into _____ and _____
the embryological cloaca divides into urogential sinus and anal canal
[cloaca is like a turn in the end of the gut tube]
what does the urogenital sinus (derived from cloaca) become in males vs females?
males - bladder (upper portion), prostate/prostatic urethra (pelvic portion), penile urethra (phallic portion)
females - bladder (upper portion), inferior vagina (pelvic portion - note superior vagina develop from müllerian ducts)
from what is the inferior vs superior vagina derived?
inferior vagina derived from urogenital sinus (which is derived form cloaca)
upper 2/3 of vagina is derived from müllerian ducts
what is the most common type of uterine anomaly?
“lateral fusion defects”: failed fusion of L/R müllerian ducts —> uterine shape is abnormal
may cause infertility, pregnancy loss
what causes a septate uterus to develop?
septate uterus: septum divides uterus into 2 endometrial cavities
due to defect in resorption of the septum between the L/R embryological müllerian ducts
most common uterine anomaly
what is the most common uterine anomaly?
septate uterus: septum divides uterus into 2 endometrial cavities
due to defect in resorption of the septum between the L/R embryological müllerian ducts
what occurs in the following uterine anomalies?
a. bicornuate
b. unicornuate
c. uterine didelphys
a. bicornuate: partial fusion of müllerian ducts (fundus is indented)
b. unicornuate: uterus connects to only 1 ovary
c. uterine didelphys: müllerian ducts fail to fuse (double uterus)
Hysterosalpingography
Imaging study in which dye is injected into the uterus to see the shape
Used to diagnose uterine abnormalities
what do the following external genitalia of the indifferent stage become in males?
a. genital tubercle
b. urogenital folds (from cloaca)
c. urogenital sinus (from cloaca)
d. labioscrotal (genital) swellings
a. genital tubercle —> phallus (aka penis)
b. urogenital folds (from cloaca) —> penile urethra
c. urogenital sinus (from cloaca) —> glands (prostate, bulbourethral)
d. labioscrotal (genital) swellings —> scrotum
hypospadia vs epispadia
congenital anomalies of the male urethra
hypospadis (more common): failure of the urethral folds to close —> ventral opening of the urethra
epispadia: abnormal position/formation of genital tubercle —> urethral opening on the dorsal side of penis, commonly occurs with bladder extrophy
what do the following external genitalia of the indifferent stage become in females?
a. genital tubercle
b. urogenital folds (from cloaca)
c. urogenital sinus (from cloaca)
d. labioscrotal (genital) swellings
a. genital tubercle —> clitoris
b. urogenital folds (from cloaca) —> labia minora
c. urogenital sinus (from cloaca) —> glands (paraurethral/Skene, Bartholin)
d. labioscrotal (genital) swellings —> labia majora
In males and females, the caudal end of the mesonephric duct forms the…
… bladder trigone and the ureteric bud that gives rise to the ureters, calyces, and collecting ducts.
In females, the rest of the mesonephric duct regresses while in males the rest of the mesonephric duct forms internal genital ducts. The mesonephric duct that forms the male internal genital ducts is also known as the Wolffian duct.
The prostate gland grows off of the ______
The bulbourethral glands grow off of the ________
The prostate gland grows off of the prostatic urethra.
The bulbourethral glands grow off of the membranous urethra or penile urethra.
