Gametogenesis & Fertilization Flashcards
which cells produced gametes
germ cells
T/F: Testes and ovaries are endodermal
F: testes and ovaries are mesodermal, sperm and oocytes were endoderm but migrated to mesodermal
detail the male germ cell growth process
male germ cell–> spermatogonium–> primary spermatocyte–> secondary spermatocyte–> spermatid–> sperm
T/F: Primary spermatocytes are haploid
False, they are diploid
what conditions lower sperm motility and how is this overcome
acidity; bulbourethral gland secretes pH neutralizing/alkaline liquid
function of epididymis
stores sperm
function of vas deferens
connects epididymis to seminal vesicles; leads into ejaculatory duct
where is sperm produced
in seminiferous tubules in testes; spermatogonium starts by basement membrane and sperm into lumen where they travel to epididymis for storage
function of sertoli cells
simulated by FSH and produces inhibin and stimulates spermatogenesis; in seminiferous tubules; also protects germ cells from noxious substances in blood
function of Leydig cells
stimulated by LH, produces testosterone which stimulates spermatogenesis and sertoli cells; neg fdbck on hypoth and pit
what are the components of semen
2/3 of volume produced by seminal vesicles –> mucous, fructose, proteins
prostate glands –> gelatinous mass, milky fluid
bulbourethral –> neutralizes acidity
what happens during puberty for males
inc in GnRH from hypoth due to lower sensitivity–> more gonadotropins released–> LH stimulates Leydig cells which produces testosterone which stimulates spermatogenesis and sertoli cells
sertoli cells are stimulated by FSH and stimulates spermatogenesis and releases inhibin that inhibits AP
what phase of meiosis is the primary oocyte arrested at
prophase 1
what phase of meiosis does the secondary oocyte arrest at
metaphase II
what stimulates the second meiotic division in a secondary oocyte
fertilization
how many days into the uterine cycle does the endometrium build up
5
when is the endometrium the thickest
5 days after ovulation
detail the ovarian cycle
Every 28 days, FSH stimulates 6-12 follicles that grow and produces estrogen which causes endomet to grow. All but one follicle degrades; estrogen = neg fdbk on hypoth/AP. Build up of estrogen switches into pos fdbck and LH surge ovulates follicle. Remaining follicular tissue –> luteum that secretes estrogen+progesterone for 2 weeks. this combo returns neg fbck on hypo/AP. If not fert, luteum degenerates, estrogen+progesterone dec, endo sloughs, neg fdbck is released. if fert occurs, hCG is secreted from blastocyst which keeps luteum functional
how does the pill work
synthetic estrogen and progesterone
abortion pill
RU-486; mifeprex- mimics progesterone- binds to progesterone receptors in endo lining and blocks it so it thinks there’s no progesterone so it sheds lining and embryo in it
why is polyspermy bad?
screws up mitosis b/c spindle fibers don’t know what to do with all the extra chromosomes
What triggers the acrosome reaction in a sea urchin?
sperm touching the jelly coat
what is contained in the acrosome
G actin (that turns to F actin when triggered)
Bindin
Digestive enzymes
what is the function of bindin
on outside of acrosomal process so when it is triggered and extends, can bind to bindin receptors on vitellin env which allows digestive enzymes to make a hole in VE so sperm can bind to PM (under VE) of egg
(digestive enzymes makes a hole in jelly coat)
what is the fert cone
triggered by bindin-bindin receptor interaction; when PM of egg surrounds sperm…both nuclei enter egg cytoplasm
detail fast block to polyspermy
when sperm enters egg Na+ influx which depolarizes egg
depolarization prevents other sperm from entering
lasts ~1 min
not in mammals
detail the slow block to polyspermy
in mammals
Ca+2 release from egg’s ER by CICR triggers cortisol granules to fuse with PM of egg–> raises the VE off from PM and hardens the VE that is now called a fert env that prevents more sperm from entering
corticol granules function
hardens/raises VE
has osmoticum that acts as a sponge–> when exposed to water it expands and since its between PM and VE, VE gets pushed away
what is the VE in sea urchins analogous to in mammals
zona pellucida
