Yan Genital System Flashcards
When is sex determined?
at fertilization (presence or absence of Y chromosome)
When does male/female morphology develop?
7th week
What are genital (gonadal) ridges and what are they derived from?
the precursor to the genitals
epithelium and condensation of underlying mesenchyme
When do germ cells appear on genital ridges?
at the 6th week
Explain how the gonads begin to develop?
PGCs-> dorsal mesentery of the hindgut->primitive gonads-> invade gonadal ridges-> development
Where do primordial germ cells originate and what are they?
endodermal cells in the wall of the yolk sac close to allantois
How do the primordial germ cells migrate from the yolk sac to the dorsal mesentery of the hindgut?
by ameboid movement
When do the PGCs arrive at the gonads?
at the beginning of 5th week
When do the PGCs invade the gonadal ridges?
at 6th week
If you don’t have PGCs will you get testes and ovaries?
NO, you need PGCs to induce the development of the testis or ovary
What happens once the PGCs arrive at the genital rides?
Epithelium of genital ridges proliferate and penetrate underlying mesenchyme to turn into primitive sex cords
When the PGCs arrive at the genital ridges and penetrate the underlying mesenchyme, it turns into the primitive sex cords. Are these sex cords of males or females?
neither, they are indifferent and can later turn into either or
How do you make PGCs turn into testis?
PGCs will have a Y chromosome with SRY (TDF) gene that will make the primitive sex cords turn into testis and medullary cords. These medullary cords will then converge at the rete testis and are covered by tunica albuginea
In the fourth month, testis cords are composed of (blank) and (blank) (derived from the surface epithelium. Somatic cell component)
PGCs and Sertoli cells
Leydig cells, derived from the original mesenchyme of the gonadal ridges, lie between the (blank). Testosterone production starts at week 8.
testis cords
(blank) is important for the development of the genital ducts and external genitalia.
Testosterone
Testis cords remain solid until (blank)
puberty
Explain what happens to the testis cords after puberty?
the cords undergo canalization (turn into canals) and become seminiferous tubules that join at the rete testis. These then connect to the efferentes ducts which link to the mesonephric duct to become ductus deferens.
How do you make ovaries by PGCs?
Lack of Y chromosome results in sex cord dissociation into irregular cell clusters and degeneration of medullary cords. Cortical cords then develop from epithelium and penetrate underlying mesenchyme. This cord splits into cell clusters surrounding PGCs and the PGC become oogonia and surround cells to become follicular cells.
So what is the major difference in differentiation between ovaries and testes?
the Y chromosome making sex cord persist
Unspecialized gonads and 2 sets of reproductive ducts exist until (blank)
week 6
What is the paramesonephric duct also called?
What is the mesonephric duct also called?
the mullerian duct
the wolffian duct
What duct must degenerate to get rid of female parts so that you will have a male?
mullerian ducts
How does the Y chromosome degenerate the mullerian ducts so that the baby will be male?
The sertoli cells secrete anti-mullerian hormones
Once you have testis you will make interstitial cells which will make (blank) and thus make all the internal and external genitalia of males.
testosterone
What makes these: Urethra Prostate Penis Scrotum
DHT
What makes these: epididymis vas deferens seminal vesicles ejaculatory duct
Testosterone (only if they have SF1)
(blank) gene activates a cascade of development events which create the testis and thus all the internal and external male genitalia
SRY
Since females do not have SRY, they will create ovaries and thus their follicles will secrete (blank) which will convert the mullerian duct (paramesonephric duct) into the (blank)
estrogen
oviducts
What three factors do you need to push the genital ridge into differentiation status?
SF1
WT1
LHX9
What 2 factors do you need to turn the sex cord into the ovary?
What 2 factors do you need to turn the sex cord into the testis?
DAX1, WNT4
SRY,SOX9
What do leydig cells need to make testosterone? and what will testosterone do?
SF1
convert wolffian duct into male genitalia
What does DHT do to the genital tubercle, urogenital sinus?
converts it into the penis, prostate
The upper portion of mesonephric duct starts to branch and form (blank)
efferent duct
The lower portion of the mesonephric duct starts to elongate and branch to make the (blank)
epididymis
The lowest portion of the mesonephric duct elongates and forms (blank) and (blank)
vas deferens and seminal vesicles
Efferent ducts, epididymis, vas deferens, seminal vesicles are all derived from (blank) under the influence of testosterone.
mesonephric ducts
In the male genitalia, the excretory tubules remain while (blank) regress and change.
mesonephros
In the male, epigenital tubules in contact with rete testis becomes (blank)
efferent tubules
In the male, the caudal portion to the testes becomes the (blank)
paradidymis
What ducts exist in both sexes?
mesonephric (wolffian ducts) and paramesonephric (mullerian) ducts
Explain what happens to the paramesonephric ducts in the female?
the come from the genital ridges and cranial end opens to abdominal cavity and the 2 caudal ends grows and fuses together to make the uterine canal and paramesonephric tubercle
Female genital ducts develop from the (blank)
paramesonephric ducts
In the female what happens to the mesonephric ducts?
mesonephric duct regresses and the remnants form epoophoron and paroophron.
What is this:
a small caudal portion of the mesonephric duct remnants in the wall of the uterus or vagina
Gartner’s Cyst
What are the three portions of the paramesonephric ducts?
upper-> uterine tube
Lower-> uterine canal
lowest-> fused part becomes corpus and cervi of the uterus
The (blank) of the uterus divides the pelvic cavity into the uterorectal and uterovesical pouches.
broad ligament
Where does the myometrium come from?
mesenchyme
The vagina has dual origin, what are they?
upper portion from the uterine canal (from paramesonephric duct)
lower portion from urogenital sinus
(blank) is the epithelial lining of the sinus and a thin layer of vaginal cells. It is frequently absent (even in virgins) although remnants are commonly present as hymenal caruncula tags.
hymen
How does the uterus and vagina form?
from the uterine canal and sinovaginal bulbs.
paramesonephric ducts extend and make cervix and top 1/3 of vagina. Sinovaginal bulb extends and makes bottom 2/3 of vagina
What are the three uterine defects?
uterus didelphys: double uterus
uterus arcuatus: slightly indented in the middle
Uterus bicornis: two uterine horns entering a common vagina
What is atresia of the cervix?
What is atresia of the vagina?
unnatural narrowing of the cervix
unnatural narrowing of the vagina
When the lower portion of the mesonephric ducts fuses you will get lumen formation which can lead to (blank).
vulnerabilities and possible defects
In week 3 of development what happens with external genitalia development?
mesenchymal cells from primitive streak migrates around the cloacal membrane.
What do the cloacal membranes turn into?
cloacal folds
The cranial portion of the cloacal folds turn into what?
genital tubercle
What does the anterior portion of the cloacal folds turn into?
urethral folds
What does the posterior portion of the cloacal folds turn into?
anal folds
Genital swellings in males turn into (blank).
in females?
scrotal swelling
labia majora
What does the genital tubercle in male turn into?
in females?
penis
clitoris
What do the urethral folds in male turn into? in females?
fuse=urethra
no fusion = labia minora
What do the genital swellings in males turn into? in females?
fuse=scrotum
no fusion= labia majora
Development of male external genitalia depends on (blank) produced by the fetal testis (leydig cells)
androgen
In the male there is rapid elongation of the (blank) making a phallus/penis
genital tubercle
(blank) pulls the urethral fold forward to make the urethral groove
phallus
What is the male urethral groove lined with?
epithelium from endoderm and makes urethral plate
In the male, At the end of the 3rd month, 2 urethral folds close over the urethral plate to make the (blank)
penile urethra
What does the solid epithelial cord of the male turn into?
turns into the lumen which turns into the urethral outlet of the glans penis
(blank) stimulates the development of the female external genitalia.
estrogen
In the female, the genital tubercle slightly elongates at becomes the (blank)
clitoris
In the female do the urethral folds fuse?
no they do not and form the labia minora
What does the genital swelling of the female turn into?
the labia majora
Can you tell the sex of a baby between the 3rd and 4th month of gestation by looking at genital tubercle?
WhY?
no
because the genital tubercle in females in larger in those months than the male
How can you tell you have a boy in the womb?
look for fusion of urethral folds, if fusion then a male
What is incomplete fusion of urethral folds with abnormal openings in the urethra along the inferior aspect of the penis?
hypospadias
Where are you most likely to get hypospadias and what is the incidence rate?
near the glans>shaft>base
3/1000 (rates been increasing over past years)
What might be the cause of hypospadias?
environmental estrogen
(blank) is a malformation in which the urethra opens on the dorsum of the penis.
epispadias
(blank) occurs as an isolate defect, but frequently associated with exstrophy of the bladder.
epispadias
A lack of mesodermal migration into the region between the umbilicus and genital tubercle, followed by rupture of the thin layer of ectoderm results in (blank)
epispadias
What is a micropenis?
2.5 standard deviations below average size for age group
What does this cause:
insufficient androgen stimulation caused by hypogonadonism or hypothalamic or pituitary dysfunction
micropenis
What happens if your genital tubercle splits?
bifid penis/double penis
Where in the SRY cascade might there be vulnerability for mutant genes?
turning cholesterol to testosterone
testosterone to DHT
DHT receptors
What causes pseudohermaphroditism?
congential adrenal hyperplasia
Are pseudohermaphrodites male or female?
female, 46 XX with ovaries and uterus
Why would excessive production of androgens cause pseudohermaphroditism?
it masculinizes external genitalia-> enlarges clitoris to male genitalia and partial fusion of the labia majora resembling scrotum
What is testicular feminization (androgen insensitivity syndrome?
it is a disease where a male looks like a female
46 XY
Testes present (cryptorchidism I.e hidden), all other genitalia is missing
What causes androgen insensitivity syndrome?
A male is born with an XY chromosome, the Y chromosome makes the SRY chromosome making testes. So this individual will have testes however remember all other steps of creating male genitalia is dependent on testosterone. SO what happens is this individual has messed up androgen receptors so they will not respond to testosterone so they will not have any male genitalia and not any female internal genitalia because the testes produce the anti murelian ducts which destroy the ability to develop female internal genitalia. But you will still make estrogen so you will have female external genitalia (cuz this is influenced by estrogen) and look like a female but have testis.
is androgen insensitivity syndrome common?
it is x-linked recessive, 1/20,000 live births
The not descended testes of androgen insensitivity syndrome patients will result in a 1/3 chance to develop malignancy. T or F
T
Describe the descent of the testes
develop in abdomen
descend to scrotum through internal ring (inguinal canal)
descends through external ring
covered in tunica vaginalis
gubernaculum attaches to caudal pole and to scrotum to assist descent
What is a fibrous cord connecting 2 structures, it is a mesenchymalcolumn of tissue that connects the fetal testis to the developing scrotum and plays a role in testicular descent.
gubernaculum
What is cryptorchidism?
one or both testes do not descend
What is this:
vaginal process fails to close and intestines pass through the rings to scrotum
inguinal hernia (indirect)
What is a hydrocele?
cysts secreting fluid
If someone has cryptorchidism, how do you get the testes to descend?
use hCG. Since they are stuck you need to do this because the testes in the cavity will be unable to undergo spermatogenesis they will have a risk of cancer
