Reproductive System Development Flashcards
WHen is genetic sex determined?
fertilization
When is phenotypic sex manifested?
about the 7th week of development
The SRY gene on the Y chromosomes is responsible for the production of what factor?
testis-determining factor
True or false: all you need for the development of ovaries is the lack of a y chromosome
false - the absence of a y chromosomes will result in ovary formation, but you need two x chromosomes in order to have complete ovarian development
Femaleness is not under hormonal influence, but estrogen is necessary for what?
feminization of the external genitalia
What is the most common abnormality of sexual differentiation?
Kleinfelter syndrome
47,XXY
1 in 850 births!
What is Klinefelter syndrome usually due to?
non-dysfunction of the XX homologues
What is Klinefelter characterized by?
infertility gynecomastia impaired sexual maturation atrophic testes small penis lack of secondary male characteristics
What is Turner syndrome?
45, XO
failure of the gonads (ovaries) to develop and infantile genitalia due to the lack of paternal sex chromosome
What characterizes Turner syndrome?
short stature high arched palate webbed neck shield-like chest inverted nipples cardiac and renal anomalies
What is ovotesticular disorder?
Basically true hermaphrodites - 46,XX
they possess both testicular and ovarian tissue (ovotestis)
it’s extremely rare
Where do the gametes migrate from into the genital gonadal ridge?
the umbilical vesicle - yolk sac
Aoub thow many primordial germ cells will enter the genital ridge during the latter part of the 5th week of development?
1000-2000
The developing gonads consist of what three groups of cells?
mesothelium
mesenchyme
primordial germ cells
In the male, the primordial germ cells migrate into what?
the cortical cords
In the female, the primordial cortical cords break apart to form what?
the follicular cells that surround the oogonia
What stage of development are those oogonia currently undergoing?
mitosis
What do the cortical cords eventually form in the males?
seminiferous tubules and serve as precursors of the sustentacular cells of sertoli
also the tubuli recti (straight tubules) and rete testis
What will develop into the efferent ductules?
remember - the mesonephric ductules
What do the efferent ductules connect to in the developing fetus?
the mesonephric duct -the distal part of which becomes the epididymis
What do the interstitial cells of leydig develop from?
mesenchyme
Leydig cells involute after birth and reappear when?
at puberty
THe sustentacular cells of sertoli don’t mature during the fetal period, but what do they produce under the influence of hCG?
anti-mullerian hormone
What does the mullerian inhibitory substance do?
suppresses the development of the paramesopheric (mullerian) ducts, so inhibist the formation of female organs
The follicular cells and the oogonia together form what?
the primordial follicles
Under the influence of meiosis-stimulating factor, the oogonia will become what?
enter meiosis I and become stuck in prophase I to become primary oocytes
The indifferent sexual duct system consists of what?
mesonephric (Wolffian) ducts
Paramesonephric (Mullerian) ducts
The caudal ends of the paramesopheric ducts fuse and terminate on what? What does this form?
the urogenital sinus - between the ends of the mesonephric ducts as the uterovaginal primordium
In males, what happens to the paramesonephric duct?
they degenerate
What two bits are left after the paramesonephric ducts ddegenerate?
prostatic utricle and appendix of the testis
Tetosterone will cause the mesonephric ducts to form what?
epidydmis
ductus deferens
ejactulatory duct
The seminal vesicles develop as outgrowths of what?
the ductus deferens (mesonephric duct)
The part of the mesonephric duct between the duct of the seminal vesicle and the urethra becomes what?
the ejaculatory duct
What does the prostate gland develop as an epithelial otugrowth of?
the pelvic portion of the urogenital sinus intot he surrounding mesenchyme
What does that surrounding mesenchyme form?
the stroma and smooth muscle of the prostate gland
What do the bulbourethral glands develop as epithelial outgrowhts of?
the spongy urethra (derived from the phalic portion of the urogenital sinus)
In the female, the absence of the anti-mullerian hormone allows the paramesonephric ducts to develop into what?
the uterine tubes and uterus
also the upper 1/3 of the vagina and the cervix
Where does development of the uterine tubes start?
develop from the cephalic, un-fused portions of the paramesonephric duct
Where does development of hte uterus begin?
from the caudal fused potion of the paramesonephric ducts a the sinus tubercle.
THe upper 1/3 of the vagina develops form the paranesonephric ducts. What about the lower 2/3?
urogenital sinus
What is the female version of the bulbourethral glands?
the greater vestibular glands
In females, the mesonephric ducts typically regress due to lack of testosterone, but a part may be found outside the uterus and vagina as what?
Gartner’s duct
What is paramesonephric duct agenesis?
It’s complete or partial absence of the uterine tubes, uterus, cervix and vagina in females with 46,xx
you still get normal development of secondary sexual characteristics vecause the ovaries are intact
you have a normal ovarian cycle without a menstrual cycle
What are some of the other odd variations of the uterus development?
double uterus (with double vagina or single vagina)
bicoruate uterus
septate uterus
unicoruate uterus
How do the testes descend?
through differential growth
What hormone is responsible for the testes movement through th einguinal canal into the scrotum?
testosterone
What does the processus vaginalis become in the male?
the tunica vaginalis
What does the gubernaculum becom ein the female?
ligament of the ovary and the round ligement of the uterus
What is the term for an undescended teste if it’s in the correct path?
cryptorchidism
What is the term for a testis that is located somewhere outside of the inguinal canal?
ectopic testis
How does an indiret inguinal hernia occur congenitally?
the processus vaginalis fails to close and bowel can herniate trhoguh the deep inguinal ring
What causes a hydrocele congenitally?
the tunica vaginalis has a potential space that can fill with fluid
The genital tubercle at the cranial end of the cloacal membrane becomes what?
the phallus
What are located on each side of the cloacal membrane at this point?
labioscrotal swelling and urogenital folds (urethral folds)
What divides the cloacal membrane into a dorsal epithelial plug (the site of the anus) and a ventral urogenital membrane?
urorectal septum
What will stimulate the phallus to enlarge and elongate into the penis?
testosterone
What will fuse to form the spongy urethra in the male?
the urogenital folds (urethral folds)
the line of fusion of the surface ectoderm on the vetnral surface - where the urogenital folds join – is called what?
the penile raphe
What makes the end of the urethra in the male/
the ectodermal cord that grows in to form the glans and connect with spongy urethra
What layer do the corpora cavernosa and ccorpus spongiosum develop from?
surrounding mesenchyme of the phallus
Labioscrotal swellings form what in the male?
scrotum
What is male pseudohermaphrodism caused by?
reduced masculine development ofthe genitalia - maybe due to inadequate amount of testosterone or mullerian inhibiting substance
What is male pseudohermaphrodism characterized by?
microphallus
hypospadiasis
can have bifid scrota
may not have testes in the scrotum
What is hypospadias due to?
failure of fusion of the urogenital folds (1 in 300)
also failure of the epithelial cord to join with the spongy urethra
What is epispadias associated with?
issue with lateral folding - associated with exxtrophy of the bladder
What does the phallus become in the feamel?
clitoris
The urogenital folds do not fuse in the female, but form what?
the labia minora
The labioscrotal swellings form what?
labia majora
