spermatogenesis Flashcards
in order to have a constant production of spermatozoids, males must have adequate secretion of GnRH, what hypothalamic center is the only active in males?
tonic center
IN seminiferous tubules at the interstitial compartment we can observe what cells that express what type of receptor to synthesize this specific hormone?
leydig cells express LH receptors an synthesize Testosterone
At the adluminal compartment what cells are observed and they express what receptors resulting in the synthesis of what hormone?
Sertoli cells express FSH receptors ad synthesize estradiol
Spermiation
once formed the release of spermatozoids from Sertoli cells into the lumen of the seminiferous tubule
Cycle of the Seminiferous tubules
period of time required for a group of cells in a section of seminiferous tubule to pass through all of the stages
Spermiogenesis
morphological conversion of round spermatid into spermatozoa
spermatogenesis
cellular mechanisms that provide continuous supply of male gametes
During this phase of the Spermiogenesis the Acrosome forms a distinct cap over nucleus, the remaining Golgi apparatus move away from nucleus and and a primitive flagellum forms from distal centriole
the Cap phase
what is the precursor of hormones such as progesterone, estradiol and testosterone?
Cholesterol
During this phase of the Spermiogenesis the Manchette migrates towards tail and the mitochondria cluster on the neck of the flagellum
The Maturation phase
During this phase of the spermiogenesis the Acrosome continues to spread and develop around the nucleus, the nucleus elongates and the Machete forms- microtubules, postnuclear cap
the Acrosomal phase
During the initial phase of the Spermiogenesis the Glogi apparatus packages enzymes that eventually will become the acrosome, also initial arrangement of cellular organelles
The Golgi phase
how many meiotic divisions are necessary to reduce a haploid spermatid?
2
how long does it take for a spermatogonia cell to become spermatozoid in bulls?
60-61 days
what is the normal spermatozoid motility in a semen collection to consider the sample optimal?
at least 60%
what is the physiological function of dihydrotestosterone in males?
various embryological structures develop, regulates along with prostate function, aids in increasing Sertoli cell, spermatogonial and spermatocyte populations
the presence of a small amount of cytoplasm in the ejaculated spermatozoid is due to
over use of the male, epididymal issues, lack of transportation time in epididymis and disease
in what organ the spermatozoids mature ad become futile and motile
epididymis
what hormone causes apoptosis of the surge center in males
testosterone transformation to Estrogen
where does spermatogenesis occur?
Sertoli cells –> seminiferous tubules
when does spermatogenesis occur?
before puberty
spermatogenesis phases;
proliferation phase , meiotic phase, differentiation phase
Proliferation phase
mitotic division of spermatogonia. Stem cell renewal
meiotic phase
genetic diversity
differentiation phase
“Spermiogenesis”- differentiation of the spermatozoids, structural changes
what changes do spermatids go through during differentiation
nucleus is high condensed, acrosome is formed, cell becomes motile, formation of the flagellum, mitochondrial helix
spermatozoa=
head + tail
head=
nucleus + acrosome + postnuclear cap
tail
middle piece + principal piece + terminal piece
what happens if there is a disruption of spermatogenesis cycle
can lead to short-to-long term stoppage in sperm production
ex: fever, stress, toxins, heat stress
how long does it take for a spermatogonia cell to become spermatozoid in rat?
approximately 54 days
how long does it take for a spermatogonia cell to become spermatozoid in man?
75-80 days
factors that affect reproductive efficiency in males
environment, Nutrition, sexual maturation of the animal, diseases, management of the animal, genetics
there is a positive correlation between what assessing scrotal circumference
positive correlation between scrotal circumference and testicular weight, number of sperm in testes and number of sperm in epididymis
different ways of semen collection
electric stimulation, manual collection, teaser, artificial vagina
ways to extract semen in bulls and stallions?
electro-ejaculator, teaser, artificial vagina
what do you look at when doing a semen analysis
volume of ejaculate, color and consistency of the ejaculate, concentration of semen, progressive motility, semen morphology, semen viability
endogenous factors that affect sperm motility?
age, sperm maturation, energy stores, surface and surface-active agents (antibodies, detergents, etc.)
exogenous factors that affect sperm motility
biophysical and physiological factors, suspending fluids, stimulation- inhibition (prostaglandins, environmental pollutants, hormonal treatments)
how to tell semen viability
cells that stain dark are no viable as the stain can enter the damaged cell, cells that are therefore not stained are viable. Cells that are not moving are motile = not viable, cells that re moving = viable
normal rate of motility in bulls
60% motility
aging in the testes is associated
decline in the number of leydig and sertoli
thickening of the basement membrane of the seminiferous tubules
arrested divisions of germ cells
