Reproductive System Development - Severson Flashcards
What area of mesoderm in the developing embryo gives rise to the urogenital system?
Intermediate Mesoderm
What areas of structures give rise to the urinary system and genital system?
Nephrogenic ridge gives rise to the URINARY system.
Gonadal/Genital ridge gives rise to the GENITAL system.
What is the difference between genetic sex and phenotypic or genital sex?
Genetic Sex: is determined at the time of fertilization
Phenotypic/Genital Sex: does not manifest until the seventh week of development
What hormone is responsible for establishing phenotypic maleness?
Testosterone
What gene is responsible for the development of the testes?
SRY gene (Sex-determining Region of Y)
-responsible for the production of testis-determining factor that induces the formation of testes
What developmental defect underlies the most common abnormality of sexual differentiation?
Klinefelter Syndrome (47, XXY)
What chromosome is lacking in Turner Syndrome?
lack of paternal sex chromosome (45, XO)
What type of tissue (testes or ovaries) would be found in the gonads of a true hermaphrodite?
Possess BOTH testicular and ovarian tissue (ovotestis)
***Extremely rare condition.
What is the source of the gametes (primordial germ cells) that migrate into the genital ridge?
Umbilical vesicle (yolk sac)
What tissues constitute the early genital ridge or gonads?
Mesothelium (coelomic epithelium) + underlying mesenchyme + primordial germ cells
The primordial germ cells in the male and female migrate into what developmental structures?
Genital (gonadal) ridge
Where are Sertoli Cells located?
Cortical cords (which later become seminiferous tubules)
What adult male structures are formed from the cortical cords?
Seminiferous tubules
Tubuli recti (straight tubules)
Rete testis
What embryologic structure forms the Efferent Ductules?
Mesonephric ductules (tubules)
What hormone stimulates the interstitial cells of Leydig to produce the androgenic hormones?
Human chorionic gonadotropin (hCG)
What hormone is produced by the Leydig cells?
Testosterone and androstenedione
What hormone stimulates the Sertoli cells?
hCG
What hormone is produced by the Sertoli cells and what effect does it have on the developing embryo?
anti-mullerian hormone => suppresses development of the paramesonephric (Mullerian) ducts
What cells give rise to the oogonia?
primordial germ cells
How are the primordial germ cells multiplied in the genital ridge?
mitosis
Why do the oogonia undergo meiosis?
they are under the influence of meiosis-stimulating factor
What cells are produced when the oogonia enter meiosis?
primary oocytes
What phase of meiosis does the primary oocyte reach before it arrests?
Prophase I of Meiosis I
What cells to the primary oocytes become associated with and what are the structures called?
Associated with FOLLICULAR CELLS => form PRIMORDIAL FOLLICLES
How do the paramesonephric (Mullerian) ducts form?
the absence of anti-mullerian hormone allows them to develop into major structures of the female genital tract (fallopian tubes + uterus)
Where and how do the caudal and cranial ends of the paramesonephric ducts terminate?
Where: in the pelvic region
How: caudal ends of the ducts fuse and terminate on the urogenital sinus between the ends of the mesonephric ducts to form the uterovaginal primordium
***Cranial end opens into the coelomic cavity
What causes the paramesonephric ducts to degenerate in the male?
anti-mullerian hormone
What remnant of the paramesonephric duct remains in the male?
prostatic utricle and the appendix of the testis
What developmental structure gives rise to the epididymis, dutus deferens and ejaculatory duct?
mesonephric ducts
From what structures do the seminal vesicles, prostate, and bulbourethral glands develop?
Seminal vesicles => outgrowth of the ductus deferens (mesonephric duct)
Prostate => outgrowth of the urogenital sinus
Bulbourethral glands => outgrowths of the spongy urethra (urogenital sinus)
What hormone is responsible for development of the epididymis, dutus deferens and ejaculatory duct?
Testosterone
What structures of the female genital tract develop from the paramesonephric duct?
fallopian tubes + uterus
What developmental structures are responsible for development of the vagina?
Upper 1/3 = paramesonephric ducts (uterovaginal primordium)
Lower 2/3 = urogenital sinus
What is responsible for Gartner’s duct?
residule parts of the mesonephric ducts outside of the uterus and vagina
What hormone is essential for the development of the female reproductive structures?
Estrogen
What developmental duct fails to develop properly resulting in malformations of the uterus and vagina?
Paramesonephric ducts
What is thought to be responsible for the descent of the testes from the posterior abdominal wall into the scrotal sac?
Guernaculum
What structure is the process vaginalis continuous with?
Tunica vaginalis
What is the fate of the gubernaculum in the female?
Ligament of the ovary (ovarian ligament) and the Round Ligament of the uterus
What would be responsible for the testes migrating to ectopic sites?
abnormal location of the gubernaculum
What is responsible for a congenital inguinal hernia?
peritoneal canal => fails to close
What is a hydrocele?
accumulation of peritoneal fluid in remains of the process vaginalis (part of scrotum)
What genital structure gives rise to the phallus?
Genital tubercle (at cranial end of cloacal membrane)
What genital enlargements occur on each side of the cloacal membrane?
Labioscrotal swellings (genital swellings) and Urogenital folds (urethral folds)
What membranes are formed when the urorectal septum comes in contact with the cloacal membrane?
Ventral => Urogenital membrane
Dorsal => Anal membrane
What hormone is responsible for development of the male genitalia?
Testosterone (converted to DHT by 5-alpha reductase)
How is the male urethra formed?
Urogenital folds fuse and form the spongy urethra.
Ectodermal cord grows in from glans and connects with the spongy urethra.
What hormones are lacking in male pseudohermaphrodites (46, XY)?
inadequate testosterone or Mullerian inhibiting substance
What structures fail to fuse in males with hypospadias?
Urogenital folds or Ectodermal cord
What other malformation is associated with epispadias?
exstrophy of the bladder
What does the phallus become in the female?
clitoris
What structures do the urogenital folds and labioscrotal folds form in the female?
Urogenital folds => Labia minora
Labioscrotal folds => Labia majora
Why do female pseudohermaphrodites have the typical female internal organs, but external genitalia that resemble that of a male?
female internal organs form as default development
external genitalia are masculine due to congenital adrenal hyperplasia (CAH) of the fetal suprarenal gland producing excessive androgenic hormones
What is lacking in the androgen insensitivity syndrome (testicular feminization syndrome)?
androgen receptor
