Development of the Repro Tract Flashcards
What is the specific order of the development of the repro tract
- Establishment of chromosomal sex
- Establishment of gonadal sex
- Development of the internal genitalia
- Development of the external genitalia
Chromosome number of the horse
64
Chromosome number of donkey
62
Chromosome number of mules
63
True or False: The number of X chromosomes determines gonadal sex.
Provide examples for either argument.
False
65, XXY (Equine equivalent of Klinefelter Syndrome in humans) have testes and are phenotypic males.
63, XO (Turner’s Syndrome) have primitive ovaries and are phenotypic females
What are some genes that are responsible for male gonadal development
SRY gene Sox 9 Fgf9 Pgds Amh
What are some genes responsible for female gonadal development
Absence of SRY**
Wnt4
Rspo1
Foxl2
Fill in the blanks: The following give rise to \_\_\_\_\_\_\_\_. Developing male sex cords -> \_\_\_\_\_\_\_\_ Primordial germ cells -> \_\_\_\_\_\_\_\_ Supporting cells -> \_\_\_\_\_\_\_\_ Tissue between cords -> \_\_\_\_\_\_\_\_
Developing male sex cords -> Seminiferous tubules
Primordial germ cells -> Spermatozoa
Supporting cells -> Sertoli cells
Tissue between cords -> Leydig cells
Fill in the blanks: The following give rise to \_\_\_\_\_\_\_\_. Developing female sex cords -> \_\_\_\_\_\_\_\_ Primordial germ cells -> \_\_\_\_\_\_\_\_ Supporting cells -> \_\_\_\_\_\_\_\_ Interstitial cells -> \_\_\_\_\_\_\_\_
Developing female sex cords -> spherical structures, ultimately follicles in cortex
Primordial germ cells -> oocytes
Supporting cells -> Granulosa cells
Interstitial cells -> Theca cells
The Mullerian duct will develop into the _______
oviduct, uterus, cervix, and cranial vagina
The Wolffian duct will develop into the _________
Epididymis
Vas deferens
Urethra
What hormone results in regression of the Mullerian ducts?
AMH
Where is AMH produced in the testicle?
Sertoli cells
also produce inhibin
What hormone stimulates the development of Wolffian ducts?
Testosterone
What cells produce testosterone in the testicle?
Leydig cells
Masculinization is caused by _________
Dihydrotestosterone
Testosterone is converted to DHT via what enzyme?
5alpha reductase
DHT directs formation of the _____ external genitalia including the _____ and _______
male, penis, scrotum
Name 3 clinical uses of AMH concentration in adult horses
Diagnostic test for presence of testicular tissue
Diagnostic test for presence of granulosa cell tumor
Estim
True or False: A horse fetus undergoes marked hypertrophy of the fetal gonad mid gestation.
True
When does gonadal hypertrophy of the equine fetus peak
~ 7 months
Testosterone in pregnant mares will peak around 200-210 days gestation
When does the testicular descent occur in the horse?
Between 30 days before and 10 days after birth.
