Reproductive system Flashcards
week 20
what are the advantages of sexual reproduction? (2)
creates variation among individuals (increases chance of survival)
unfavourable genes may be less likely to be passed on to the next generation
what are the disadvantages of sexual reproduction? (5)
need male and female
effort to choose mates
produces fewer offspring than asexual reproduction
may prevent favourable genes from being passed on to offspring
may lose diversity by losing unfavourable genes
define gonad
the organ where gametes are produced
produce hormones that control secondary sexual characteristics
define germ cells
examples (2)
any cells in the series of the germ line that eventually become gametes and often indicate the cells before meiosis
spermatagonia (males)
oogonia (female)
where do primordial germ cells arise?
in the posterior yolk sack and stay there until gonads are formed
where do gonads arise from?
the genital ridge (becomes testis or ovary)
where do primordial germ cells migrate?
into the gonad and then reside as germ cells
at puberty what does testosterone cause? what does it allow?
maturation of seminiferous tubeless in the testis
allows spermatogonia to further proliferate and enter meiosis
some spermatogonia enter meiosis while others…
proliferate and remain as spermatogonia
they function as stem cells
what are testis made from?
seminiferous tubules
what is the function of sertoli cells? (2)
produce enzymes and growth factors required for spermatogenesis
function as a phagocyte to clean up residual cytoplasm of sperm
what do sertoli cells span?
from the basement membrane to the lumen surrounding differentiating spermatogonia
what is the function of Leydig cells (interstitial cells)?
secrete testosterone in response to LH
where is LH produced?
pituitary gland
where are Leydig cells?
outside of seminiferous tubule
