The Making of the Male Flashcards
where do the testicles form?
in the gonadal ridge of the foetus
when do the testicles descend to scrotum?
before puberty
before or shortly after birth in most species
What is anorchidism?
failure of testicular development (rare)
cryptorchidism?
temporary of permanent failure to descend (testicles)
retained testis?
normal steroidogenesis but no spermatogenesis. prone neoplasia
what is scrotal positioning essential for?
for fertility
structure of the testes?
usually symmetrically-paired ovoid structures
where are the testes housed? what are the different types?
housed in scrotum
- pendulous
- non-pendulous
- intermediate
pendulous scrotum?
e.g. bull and ram
they protrude ventrally in inguinal region
non-pendulous scrotum?
e.g. tom cat and boar
protrude caudally in perineal region
intermediate scrotum?
e.g. stallion and dog
protrude into caudal inguinal region
when does fertile semen production begin?
at puberty
what type of glands are the testes?
they are both exocrine and endocrine glands
rete testes in stallion?
it is central in stallion and non-central in other species
two components of the testes?
interstitium
seminiferous tubules
what does the interstitium component contain?
leydig cells for androgen synthesis
blood and lypatic vessels
fibroblasts and connective tissue
what does the seminiferous tubule component contain?
spermatogenesis
how are the interstitium and seminiferous tubules components of the testes structurally and physiologically distinct?
cellular barriers form at puberty to limit movement of hydrophilic substances between compartments
testicular parenchyma?
interstitial tissue and seminiferous tubules
when does spermatogenesis begin?
at puberty
DSO?
Daily sperm output
describe the DSO?
increases from puberty and remains relatively constant through life
how can DSO be estimated?
from scrotal dimensions
what happens to DSO with old age?
decreases but doesn’t cease with old age
ideal scrotal circumference for bull and ram?
bull: >36cm
ram: >34cm
How do spermatocytes form spermatids?
1y spermatocytes (2n) > leptotene > zygotene > pachytene > diplotene > 2y spermatocytes > round spermatids (n)
round spermatids are hap/diploid?
haploid after spermeogenesis
what is spermiogenesis?
round > elongated > mature
what is spermination?
when the mature sperm is released
what happens to excess cytoplasm?
chromatin condensed
flagellum and midpiece form
acrosome formed
cytoplasm shed
spermatogenic cycles?
stage of spermatogenic cycle differs in adjacent regions of tubules
finite region of tubules releasing sperm at a given time
ordered progression
time for completion of spermatogenesis to occur - man? and duration of epithelial cycle?
64 days
16 days
time for completion of spermatogenesis to occur - bull? and duration of epithelial cycle?
54 days
13.5 days
time for completion of spermatogenesis to occur - ram? and duration of epithelial cycle?
49 days
12.25 days
time for completion of spermatogenesis to occur - boar? and duration of epithelial cycle?
34 days
8.5 days
time for completion of spermatogenesis to occur - stallion?
58 days
12.2 days
testosterone travels to sertoli cells, what does this do>
stimulate production of sperm
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it creates a negative feedback loop which keeps the production of semen under control and fairly constant - limits the reaction to the sertoli cells
increase in testes length?
increase in LH pulses (LH pulses = an increase in LH levels)
