Development Of Reproductive Tracts Flashcards
What happens 30 hours after fertilisation?
Fertilised egg splits into two blastomeres
How many divisions until the oocyte becomes the morula?
4 (16 cells)
What structure originating from the hindgut becomes the common opening of the reproductive and urinary tracts?
Cloaca - Urogenital sinus
How does the SRY region of the Y chromosome determine sex?
Producing a transcription factor initiating a cascade of downstream genes (testis determining factor TDF)
What is the first step of the development of the reproductive system?
Primordial germ cells migrate along retro peritoneum to the gonad at the urogenital ridge
What three sources make up the gonad?
Mesothelium
Underlying mesenchyme
Primordial germ cells
Which cords develop in males?
Which cords develop in females?
Medullary cords
Cortical cords
Which duct persists in males?
Which duct persists in females?
Mesonephric (Wolffian) duct
Paramesonephric (Mullerian) duct
What structures does the mesonephric duct become if stimulated by androgens?
Rete testis and vas deferens
What dictates the prescence of each duct?
Mesonephric - prescence of androgens from testes
Paramesonephric- abscence of androgens and MIH secreted by testes
How do the male external genitalia form?
Genital tubercle elongates
Genital folds fuse to form spongy urethra
Genital tubercle develops into glans penis
How do the external genitalia of the female form?
No fusion of genital folds gives rise to labia majors and minora
Genital tubercle develops into clitoris
What drives the descent of the gonads in males and females? Why can the female genitalia not descend?
Gubernaculum (caudal genital ligament)
Uterus prevents descent of the ovary in females, and the gubernaculum degenerates forming the round ligament
What does a person of 45X0 makeup suffer from?
What are the clinical signs?
Turners syndrome
Short stature, high arched palate, webbed neck, shield like chest, cardiac and renal abnormalities, inverted nipples
What is Klinefelter syndrome?
What are some clinical signs?
Karyoptype 47 XXY or XXXY etc Decreased fertility Small testes Low testosterone levels Gynecomastia (enlarged breasts) in 33%
What is the most common cause of ambiguous genitalia?
Congenital adrenal hyperplasia - genetically female but exposed to androstenedione by the adrenal glands causing external masculisation of genitalia
What’s the most common cause of sexual ambiguity in males?
Androgen insensitivity syndrome - lack of androgen receptors in tissue
Note: testes still produce MIH so paramesonephric system is still supressed
