Gametogenesis Flashcards
Where to primordial germ cells start then go?
They start in the wall of the yolk sac during the 2nd week then migrate to the gonads during the 4th week and start mitosis
What is the sequence of cells for oogenesis?
Primordial germ cell oogonia primary oocytes primordial follicle primary follicle secondary follicle mature follicle
What stage does the primordial follicle arrest in?
diplotene/ prophase 1
What is the theca folliculli and what does it do?
It surrounds the the growing primary follicles and produces hormones
What do the follicular cells around the primary follicle do?
secrete a glycoprotein layer called the zona pellucida
What happens in the secondary follicle?
the antrum (fluid filled space between granulosa cells) begins to develope and the oocyte is found on the edge of the antrum (cumulus oophorus)
What happens to the mature follicle?
a surge of LH induces it to complete meiosis I and it arrests in metaphase II about 3 hours before ovulation
What are the sequential stages of cells for spermatogenesis?
primordial germ cells Type A spermatogonia Type B spermatogonia primary spermatocytes secondary spermatocytes spermatids spermatozoa
What are the steps of spermiogenesis?
formation of acrosome
condense nucleus
form tail and related structures
shed cytoplasm
What is spermatogenesis regulated by?
LH
What are the genetic causes of down syndrome (trisomy 21)
95% = meiotic nondisjunction (mostly oocyte) 4% = unbalanced translocation 1%= mosaicism due to mitotic nondisjunction
What is Klinefelter syndrome?
XXY; usually nondisjunction of the XX homologues in oogenesis
What is Turner syndrome?
45, X= missing sex chromosome
