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Veterinary Physiology: The Reproductive System
exam 3 repro
109
Physiology
Professional
03/15/2012

Additional Physiology Flashcards

 


 

Cards

Term
main component of testicular parenchyma
Definition

seminiferous tubules

 

Term
3 methods of scrotal testicle temp regulation
Definition
  • sweat glands
  • contraction and relaxation of muscles (cremaster and tunica dartos)
  • pampiniform plexus: countercurrent exchange
Term
spermatogonia
Definition
male stem cells
Term
spermatozoa
Definition
motile sperm cells
Term
spermatogenesis
Definition
development of spermatogonia into spermatozoa in the seminiferous tubules
Term
steps of spermatogenesis
Definition

1. spermatocytogenesis: mitosis of spermatogonia

2. meiosis: results in haploid germ cells (round spermatids)

3. spermiogenesis: differentiation / metamorphosis of round spermatids to spermatozoa

Term
sertoli cells
Definition
  • sustentacular or nurse cells: contact all stages of spermatogenesis
  • secrete estrogens, inhibin, activin, GnRH like peptide, proteins, lactate, pyruvate, tubule fluid
  • tight junctions form blood-testis barrier (along with myoid cells): prevent escape of sperm/ control environment to be specific for sperm
Term
2 main differences between spermatogenesis and oogenesis
Definition

1. male germ cells are replenished while female decrease during life

2. males continue mitosis while females stop soon after birth (preset number of formed germ cells)

 

Term
primary spermatocytes
Definition
result of mitosis; committed to meiosis
Term
2 important features of meiosis (sperm)
Definition

1. chromosome number reduces from diploid to haploid

2. crossing over (chiasma/formation of tetrads) results in more genetic diversity among gametes

Term
meiosis stage most vulnerable to damage (sperm)
Definition

pachytene (part of prophase)

damage by high testicular temp or inappropriate gonadotrophin levels

Term
secondary spermatocytes
Definition

contain half of chromosomal complement

undergo second meiosis: duplicated chromosomes each go into one daughter cell

Term
spermiogenesis changes
Definition

acrosome forms

flagellum forms

cytoplasmic volume decreases

Term
spermiation
Definition

gradual release of spermatozoa into lumen of seminiferous tubules

still has residual body (cytoplasmic droplet) - removed by sertoli cells in the lumen

Term
4 cell association stages in spermatogenic cycle
Definition

1. E Elongation (postrelase)

2. G Group formation (premeiotic)

3. M Maturation (postmeiotic)

4. R Prerelease

EGMR: least to most advanced component cell associations

Term
DNA synthesis main stage (sperm)
Definition
preleptotene during R stage
Term
interval between testicular damage and abnormal sperm appearance in ejaculate
Definition

30-60 days depending on location of damage

represents interval between sensitive preleptotene stage and ejaculation

Term
spermatogenic wave
Definition

describes sperm development by spatial arrangement

from rete outward: RMGE

site of reversal in seminiferous tubule

EGMR

reach rete again: RMGE

Term
GnRH
Definition
from hypothalamus: stimulates pituitary release of LH, FSH, prolactin
Term
LH (male)
Definition

triggers Testosterone production from Leydig cells

 

Term
prolactin (male)
Definition
facilitates interaction of LH w Leydig cells
Term
FSH (male)
Definition
gonadotrophic support for Sertoli cells
Term
Testosterone (male)
Definition

from leydig cells

essential for development and maintenance of spermatogenesis, other male characteristics

Term
inhibin (male)
Definition

from sertoli cells in response to FSH stimulation

inhibits anterior pituitary to reduce FSH

negative feedback loop

Term
activin (male)
Definition

from sertoli cells

stimulates anterior pituitary to stimulate FSH production

Term
androgen binding protein
Definition

from sertoli cells

triggers spermatocytogenesis via androgens, moves testosterone to blood vessels and lymph for distribution to rest of body

Term
GSH (glutathione) (male)
Definition

from sertoli cells

important spermatogenic cell intracellular reductant and detoxicant

Term
estrogens (male)
Definition
  • result of testosterone conversion by sertoli cells
  • present in adluminal and basal conpartment of seminiferous tubules and in bloodstream
  • synergistic effect w testosterone: negative feedback
  • can be measured to determine presense of cryptorchid in males without outer testicles (eg. determine gelding or cryptorchid)
Term
dihydroxytestosterone
Definition

converted form of testosterone in sertoli cells

greater biological potency than T

Term
origin of androgens in castrated males
Definition
adrenals
Term
myotropic effect
Definition
  • result of testosterone concentrations
  • anabolic or nitrogen retention effect involving increase in muscle mass
  • also results in deeper voice from thicker vocal cord muscles

 

 

Term
puberty (male)
Definition
initiation of ability to release mature germ cells
Term
gonadostat hypothesis
Definition
reduced sensitivity of the hypothalamus and pituitary to negative steroid feedback resulting in higher sex hormone concentration (important for puberty)
Term
sexual maturity (male)
Definition
process of becoming an effective breeder
Term
long day breeders (male)
Definition

increase in photoperiod brings on increased spermatogenic and endocrine functions of gonads

ex: stallion

Term
short day breeders (male)
Definition

decrease in photoperiod brings on increase in testicular function

ex: sheep and goats

Term
light influence on reproduction mechanism
Definition
  • hypothalamus and pineal gland are involved
  • inc GnRH and LH
  • leydig cells respond to pattern of LH release, not amount
  • smaller amplitude but longer duration of LH: release large amounts of testosterone
  • FSH increase but circulating levels decrease once activation is complete
Term
androgen metabolites
Definition

secreted as salivary pheromones

also contribute to boar taint meat

Term
flehmen response
Definition

lip curls up to block nostrils, breathe in through mouth

vomeronasal organ used to detect less volatile pheromones in female

Term
erection caused by ____ nervous system
Definition
parasympathetic
Term
active ejaculation caused by ____ nervous system
Definition

sympathetic

follows emission, forces spermatozoa and secretions into urethra

glans penis -> internal pudendal -> spinal cord reflex arc

Term
passive ejaculation caused by ____ nervous system
Definition

parasympathetic

hypogastric plexus -> urethralis, ischocavernosus and bulbospongiosus muscles

Term
fibroelastic pene
Definition

sigmoid flexure straightens w relaxation of retractor penis muscle

still have vascular component of erection

increase in penile diameter limited by CT (show-ers nor grow-ers?)

ex: bulls, boars and rams

Term
vascular pene
Definition

relaxation of retractor penis muscle and penile engorgement result in significant increase in diameter and length of penis

(grow-ers not show-ers?)

ex: stallion

Term
vascular process of erection
Definition
  • vasodilaton of ateries mediated by nitric oxide
  • intermittent contractons of ischiocavernosus muscles
  • compression of penile veins
  • blood trapped in cavernosus sinuses
Term
intromission
Definition

entry of penis into vagina

marks initiation of coitus

Term
reaction time (male)
Definition
time required for male to mount an estrus female after entering breeding area
Term
semen
Definition

combination of spermatozoa and seminal plasma

product of ejaculation

Term
oxytocin (male)
Definition

posterior pituitary

effects contraction of epidydimal smooth muscle

forces more sperm cells into the male duct system for ejaculation

Term
maturation of sperm: location
Definition
head (caput) and body (corpus) of epidydimus
Term
storage of sperm: location
Definition
tail (cauda) of epidydimus
Term
epidydimal secretions
Definition

maintain spermatozoa in a quiescent state with little oxidizable substrates and high concentration of potassium

in tail of epidydimus: cells become capable of motility from forward motility protein located there

Term
protoplasmic (cytoplasmic) droplet
Definition
sign of poor epidydimal storage
Term
accessory glands
Definition

ampulla

seminal vesicles

prostate

bulbourethral

Term
prostate
Definition

disseminate: surround urethra without penetrating voluntary muscle

discrete: form definite body around urethra

concentrates zinc; secretes fructose, citric acid, cholesterol, proteins, amino acids, enzymes

spermine: human only

Term
ampullae
Definition

enlargements of distal ends of ductus deferens

most prominent in dog and stallion

stallion: produce some inositol, ergothioneine

Term
vesicular glands
Definition

secrete fructose,inositol, ergothioneine, citric acid, amino acids, proteins, potassium, lipid, phosphorylcholine, prostaglandins

absent in dog

Term
bulbourethral glands
Definition

located near the bulb of the penis

prepare urethra for ejaculation

erect penis creates pressure, squeezing glands

secretions rinse urine from the urethra and raise pH

absent in the dog

Term
contents of seminal plasma
Definition

electrolytes, fructose, ascorbic acid, enzymes, vitamins, hormones, growth factors

more important in species with vaginal depositon of sperm as opposed to cervical or uterine

Term
sperm capacitation
Definition

in female reproductive tract

renders sperm cell capable of fertilizing an egg

removal and/or alteration of seminal plasma protein components that stabilize membranes of sperm cells

Term
acrosome reaction
Definition

necessary for sperm to interact with egg

release of egg penetrating enzymes

Term
scrotal cirfumerence
Definition
used to estimate testicular weight which is correlated with sperm production
Term
sperm evaluation
Definition

motility: at least 70% motile

morphology: should 70% or more normal

sperm concentration

Term
primary abnormality of sperm
Definition

abnormalities acquired during development in the testis

important for fertility: should be less than 20% primary defects

Term
prolactin (female)
Definition

onset of lactation, CL functioning

negative control by dopamine

increased by increased photoperiod, suckling and nursing, estrogens

Term
main ovarian steroids in estrus cycle
Definition

estradiol: from growing follicle

progesterone: from corpus luteum

Term
FSH (female)
Definition

stimulates follicle growth (not initial development)

directs granulosa cells to convert androgens to estrogens (aromatase enzymes)

 

 

Term
LH (female)
Definition

final maturation of follicle and ovulation

supports CL formation

directs androgen synthesis by thecal cells

Term
puberty (female)
Definition

first estrus with ovulation, followed by normal CL formation and function

mechanism controlled by hypothalamus and GnRH

 

Term
silent ovulation
Definition
ovulation without estrus
Term
silent ovulation
Definition
ovulation without estrus
Term
first estrus
Definition
associated with 2nd or 3rd LH surge
Term
duration of estrous cycle
Definition
time from onset of estrus till estrus occurs again
Term
seasonally polyestrus
Definition

undergo multiple estrous cyles in a limited time of year

ex: sheep, goats, horses

Term
nonseasonal polyestrous
Definition

cycle throughout the year

ex: cow, sow

Term
monestrus
Definition
period of estrus followed by anestrus
Term
induced ovulators
Definition

require copulation to ovulate

ex cat, rabbit, llama, camel

Term
estradiol
Definition

from ovary

induces estrus

stimulates GnRH secretion and increases pituitary sensitivity to GnRH

positive feedback effect causes LH surge and smaller FSH surge

Term
estrus
Definition

period of sexual receptivity

ovulation occurs during or shortly after estrus

 

Term
metestrus
Definition

period for establishing CL activity

interval between estrogen and progesterone dominance of the cycle

Term
diestrus
Definition

when CL has become functional

progesterone concentrations increase

longest phase of cycle (cow)

Term
proestrus
Definition

luteolysis

decrease in progesterone

rapid follicle growth

 

Term
signs of estrus
Definition

all species: accept mounting by male

cows: stand to be mounted by females (that may or may not also be in estrus)

ewes: seek male

mare: breeding stance and winking of clitoris

gilt or sow: rigid with ears erect, can sit on its back

queen: vocalising! and lordosis, treading

bitch: sanguineous secretions due to estrogens

Term
stimulation of estrus behavior
Definition

pheromones

tactile stimulation

presense of a male

Term
menstrual cycle
Definition

no limit to sexual receptivity

start cycle at first day of menstruation

prominent sloughing of endometrial lining due to loss of gonadal steroids

follicular growth dominates the cycle (not luteal phase)

estradiol stimulates endometrial proliferation

ovulation occurs mid-cycle

 

Term
proliferative phase
Definition

menstrual cycle

follicular phase

encreased estradiol causes endometrial proliferation

 

Term
secretory phase
Definition

menstrual cycle

luteal phase

endometrial glands secrete fluid into the uterine lumen

Term
development of oocytes
Definition

at birth: oogonia (germ cells) undergo meiotic division to become oocytes

oocytes stay in resting phase until puberty

meiosis is resumed in a few cells during each estrous cycle

oogenesis occurs simultaneously with follicular growth

Term
primary follicles
Definition

oocyte surrounded by granulosa cells and thecal cells with basement membrane in between

 

Term
zona pellucida
Definition

formed by granulosa cells in early follicular growth

mucopolysaccharide membrane surrounding oocyte

Term

secondary follicle

 

Definition
increased granulosa cells and zona pellucida present
Term
atresia
Definition

follicle does not undergo ovulation so it regresses

loss of antrum (fluid cavity), shrinking of nuclei

almost all follicles become atretic

viable follicles have high estradiol concentration in follicular fluid while atretic follicles have elevated androgens

Term
follicular waves
Definition

groups of follicles initiate growth

first wave occurs after gonadotropin surge before ovulation

one follicle becomes primary while others regress

sheep, cattle and horses have waves during luteal phase

pig, rat and human only during follicular phase

waves also occur during pregnancy and before puberty

 

Term
two-cell-two-gonadotropin model
Definition

biosynthesis of follicular estradiol

LH directs androgen synthesis in thecal cells

FSH directs androgen conversion to estrogens in granulosa cells

Term
dominant follicle maintenance
Definition
secrete inhibin and estradiol which suppresses FSH so other follicles don't develop
Term
meiosis of oocytes
Definition

first division normally complete prior to ovulation 

second division completed at time of fertilization

 

Term
primary oocyte
Definition

prior to first meiosis

in bitch, primary oocyte is ovulated

Term
secondary oocyte
Definition
after first meiosis
Term
ovulation changes
Definition

increase in PGE and F

formation of multivesicular bodies: proteolytic enzymes digest ground substance to allow escape of oocyte

Term
luteal phase
Definition
metestrus and diestrus
Term
small luteal cells
Definition

originate from theca

responsive to LH

 

Term
large luteal cells
Definition

originate from the granulosa

not responsive to LH

secrete majority of basal progesterone

Term
luteotropic agents
Definition

cow: LH, hCG, GnRH

rat: prolactin

canine: LH and prolactin

rabbit and pig: estrogen

Term
long day breeders (female)
Definition

cat, horse

melatonin determines breeding season

 

Term
male effect
Definition
presence of male hastens onset of puberty or breeding season
Term
flushing
Definition

sudden increase in feed intake to stimulate ovulation rate

in pigs and sheep

Term
block to polyspermy
Definition
cortical granules released from oocyte in response to penetration by spermatozoon changing zona pelucida and vietlline membrane
Term
syngamy
Definition
male and female pronuclei move together, membranes break down and the chromosomes intermingle
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