Embryology Flashcards
Both genital and urinary systems arise from _________ They are functionally distinct but __________
intermediate mesoderm
developmentally interwoven
Chromosomal sex is determined at _________
fertilisation
Despite chromosomal sex being determined at fertilisation there is no _______________ until ________ this period is known as the _____________
anatomical or morphological indications of sex until the seventh week
the period before this is the indifferent phase
During weeks 4-6 PGCs within the yolk sac migrate via dorsal mesentery to ______1______
___2______ epithelium proliferates and thickens to form _____3_____
Proliferating epithelium will form somatic supports cells which envelop the ____4____
This forms ______5_______
1) intermediate mesoderm
2) coelomic
3) genital ridges
4) PGC’s
5) primitive sex cords (primary sex cords)
Describe development of the genital ducts at weeks 4-6?
Round weeks 4-6 there is development of the genital ducts which at this point are the same in both female and male
Two ducts:
> Mesonephric (Wollfian (OLD TERM)) duct
Mesonephric eventually forms parts of male repro system
> Paramesonephric (Mullerian) duct
Paramesoneprhic eventually forms part of female repro system
Which duct forms part of the male reproductive system?
mesonephric / wollfian
Which duct forms part of the female reproductive system?
paramesonephric / mullerian
Sexual differentiation occurs from week _____ onwards
seven
What allows female development to occur?
There is lack of SRY gene which is found on the Y chromosome and what triggers male development
What allows female development to occur?
There is lack of SRY (sex determining region) gene which is found on the Y chromosome and what triggers male development
Describe female development?
Germ cells differentiate into oogonia and then into primary oocytes
Somatic support cells differentiate into granulosa cells and surround the primary oocytes
This forms primordial follicles in the ovary (oocytes halted in prophase 1, can be in this phase for decades), the female gonad also forms thecal cells
Influence of oestrogens stimulates formation of the female external genitalia and development of paramesonephric ducts.
Paramesonephric (Mullerian) ducts give rise to:
Uterine tubes
Uterus
Superior vagina
What allows male development to take place?
sex determining region (SRY) gene is present on the Y chromosome which triggers male development by stimulating the formation of sertoli cells, sertoli cells secrete AMH (anti-mullerian hormone) which results in degeneration of the paramesonephric duct, sertoli cells also stimulate the gonadal ridge to form Leydig cells which secrete testosterone stimulating formation of the epididymis, vas deferens and seminal vesicles
What are the 3 male accessory glands, where do they develop and during what week?
develop near the junction of the mesonephric duct and the urethra
prostate, bulbourethral, seminal vesicles
