Gametogenesis & Fertilization

Question 1

which cells produced gametes

Answer 1

germ cells

Question 2

T/F: Testes and ovaries are endodermal

Answer 2

F: testes and ovaries are mesodermal, sperm and oocytes were endoderm but migrated to mesodermal

Question 3

detail the male germ cell growth process

Answer 3

male germ cell–> spermatogonium–> primary spermatocyte–> secondary spermatocyte–> spermatid–> sperm

Question 4

T/F: Primary spermatocytes are haploid

Answer 4

False, they are diploid

Question 5

what conditions lower sperm motility and how is this overcome

Answer 5

acidity; bulbourethral gland secretes pH neutralizing/alkaline liquid

Question 6

function of epididymis

Answer 6

stores sperm

Question 7

function of vas deferens

Answer 7

connects epididymis to seminal vesicles; leads into ejaculatory duct

Question 8

where is sperm produced

Answer 8

in seminiferous tubules in testes; spermatogonium starts by basement membrane and sperm into lumen where they travel to epididymis for storage

Question 9

function of sertoli cells

Answer 9

simulated by FSH and produces inhibin and stimulates spermatogenesis; in seminiferous tubules; also protects germ cells from noxious substances in blood

Question 10

function of Leydig cells

Answer 10

stimulated by LH, produces testosterone which stimulates spermatogenesis and sertoli cells; neg fdbck on hypoth and pit

Question 11

what are the components of semen

Answer 11

2/3 of volume produced by seminal vesicles –> mucous, fructose, proteins
prostate glands –> gelatinous mass, milky fluid
bulbourethral –> neutralizes acidity

Question 12

what happens during puberty for males

Answer 12

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

Question 13

what phase of meiosis is the primary oocyte arrested at

Answer 13

prophase 1

Question 14

what phase of meiosis does the secondary oocyte arrest at

Answer 14

metaphase II

Question 15

what stimulates the second meiotic division in a secondary oocyte

Answer 15

fertilization

Question 16

how many days into the uterine cycle does the endometrium build up

Answer 16

5

Question 17

when is the endometrium the thickest

Answer 17

5 days after ovulation

Question 18

detail the ovarian cycle

Answer 18

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

Question 19

how does the pill work

Answer 19

synthetic estrogen and progesterone

Question 20

abortion pill

Answer 20

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

Question 21

why is polyspermy bad?

Answer 21

screws up mitosis b/c spindle fibers don’t know what to do with all the extra chromosomes

Question 22

What triggers the acrosome reaction in a sea urchin?

Answer 22

sperm touching the jelly coat

Question 23

what is contained in the acrosome

Answer 23

G actin (that turns to F actin when triggered)
Bindin
Digestive enzymes

Question 24

what is the function of bindin

Answer 24

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)

Question 25

what is the fert cone

Answer 25

triggered by bindin-bindin receptor interaction; when PM of egg surrounds sperm…both nuclei enter egg cytoplasm

Question 26

detail fast block to polyspermy

Answer 26

when sperm enters egg Na+ influx which depolarizes egg
depolarization prevents other sperm from entering
lasts ~1 min
not in mammals

Question 27

detail the slow block to polyspermy

Answer 27

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

Question 28

corticol granules function

Answer 28

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

Question 29

what is the VE in sea urchins analogous to in mammals

Answer 29

zona pellucida