quiz 6 Flashcards
do males have a surge or tonic center
tonic
where is GnRH secreted from
tonic center
where are LH and FSH secreted from
anterior pituitary
how often is LH pulsated
it occurs 4-8 times a day and lasts for 10 to 20 minutes
how often is FSH pulsated
less than LH but it lasts longer due to a longer half life
why does LH bond to leydig cells
to create progesterone which will later become testosterone
what does testosterone become in Sertoli cells
dihydrotestosterone and E2
what do Sertoli cells produce
E2, inhibin, and androgen binding
define spermatogenesis
the creation of spermatozoa
what are the 3 steps of spermatogenesis
- proliferative phase (mitosis)
- meiotic phase (meiosis)
- differentiation phase
how often are new sperm released
13.5 days
how many copies of DNA do spermatids have
1 copy
define apoptosis
cell death
how many spermatid are created
256
how many divisions occur
2-6
why can apoptosis occur
season
disease
trauma
heat
hormone levels
normal
define spermatogenesis
trasformation of round spermatid to elongated spermatid
what are the four phases of spermatogenesis
Golgi, cap, acrosomal, maturation
describe the Golgi phase
Golgi apparatus produces the acrosome which migrates to one end of the nucleus, centrioles migrates to the other end of the nucleus where the tail will form
describe cap phase
acrosome forms a distinct cap, Golgi moves away nucleus, flagellum forms
describe acrosomal phase
acrosome spreads around nucleus
manchette forms and creates tail
microtubules form
nuclear elongation
describe maturation phase
manchette migrates to tail and disappears
mitochondria migrate toward and closer around the flagellum
dense outer fibers and fiberous sheath forms
spermatid becomes spermatozoa
when does spermiation occur
the end of spermatogenesis
what does spermiation do
prepares the sperm with the cytoplasmic droplet
what can cause a temporal relationship
heat
stress
fever
toxin exposure
define stages
specific cellular associations within a small segment of seminiferous tubules
define cycles
progression through sequence of all stages
how many cycles are needed for spermatozoa
4-5
define wave
some portion of seminiferous tubule is always releasing sperm into the rate testes
what does the vascular system provide
nutrients, oxygen, growth factors, and hormones
describe basal
mitosis
spermatogonia and primary spermatocytes
describe adluminal
meiosis and spermatogenesis
primary and secondary spermatocytes, spermatids
describe lumen
spermiation
what creates the blood testis barrier
Sertoli cells and tight junctions
when does the blood testis barrier occur
at puberty
what can harm the tight junctions
heat, metal, endocrine disrupters, pesticide, and lack of FSH and testosterone
what is the epididymal function
maturation- change in fertility, develops motility, nuclear condensation, cytoplasmic droplet
concentration- removes water
secretion- t -> dht, energy, glycoproteins, lipids and enzymes
transport- smooth muscle contraction
storage- cauda
what are the 3 variations of spermatogenesis
testis size
efficiency (mitosis and degeneration)
length of spermatogenesis
what are the components of sperm
water
sperm
substrates
inorganic salts
proteins
define anestrus
female does not have repeating estrous cycles
what are the 3 types of estrus?
polyestrous
seasonal polyestrous
monoestrous
define follicular phase and name the dominant hormone
follicles are more dominant in the ovarian structures
estrogen
define luteal phase and name the dominant hormone
corpora lutea is dominant ovarian structure
progesterone
describe the follicular phase
follicles grow, LH surge, dominant follicle grows, 20% of cycle
describe the luteal phase
80% of cycle, dominated by corpus leteum, CL undergoes regression or luteolysis to form corpus albicans
what stages make up the follicular phase? the luteal phase?
proestrus, estrus
metestrus, diestrus
describe proestrus
proceeds estrus
begins when P4 declines
P4 morphs to E2
preovulatory follicles enlarge
vascularity inceases
endometrial glands grow
estrogen levels peak
describe estrus
behavioral changes and more receptive to breeding
estrogen decreases
LH surge occurs
ovulates 24-48 hours after LH surge
high uterine motility
sperm transport is optimal
cervical mucus volume increase
FSH and LH increase
describe metestrus
E2 and P4 are low
ovulation in cow
corpus hemorrhagic present and remodels into CL
contractions subside
endometrial glands grow
in cattle bleeding occurs
FSH increases
no longer makes inhibin
triggers follicular growth
describe diestrus
longest phase
P4 is high
FHS increases at some point to initiate growth of next follicle
uterus secretes fluid but gradually slows
contractions stop
CL regresses if not pregnant
