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LBB 3 Mens Bodies.ppt
LBB_3_Mens_Bodies.ppt
Showing 43-56 out of 148
LBB 3 Mens Bodies.ppt-Men’s Bodies LeVay, Baldwin ...
LBB_3_Mens_Bodies.ppt-Men’s Bodies LeVay, Baldwin & Baldwin,
LBB 3 Mens Bodies.ppt-Men’s Bodies ...
LBB_3_Mens_Bodies.ppt-Men’s Bodies LeVay, Baldwin & Baldwin,
Page 43
The Testicles Produce Sperm and Sex Hormones
The testicles require a specific temperature
range for production of sperm, several
degrees below core body temperature.
About 150 million are produced each day,
but studies show that sperm counts are
decreasing in several countries.
Possible reasons include tight-fitting pants,
sedentary lifestyles, and environmental
pollutants, especially endocrine disrupters.
Page 44
Box 3.4
Declining Sperm Counts (Part 1)
Page 45
Box 3.4
Declining Sperm Counts (Part 2)
Page 46
•
After leaving the seminiferous tubules, sperm pass
through a space called the rete testis before entering the
epididymis.
•
Behind each testis is a C-shaped epididymis through
which sperm travel and mature.
•
The vas deferens are a set of tubes that carry mature
sperm away from each epididymis.
Page 47
Figure 4.6
Internal structure of the testis and epididymis
Page 48
Internal structure of the
testis and epididymis
Page 49
Drawing of a cross section of a seminiferous tubule
Page 50
Testicles
Seminiferous tubules are the site of
spermatogenesis.
Spermatocytes are attached to Sertoli cells
by tight junctions: nourish & control
maturation
(similar to granulosa cells in
females
).
Behind each testis is an epididymis
through which sperm pass.
The vas deferens moves mature sperm
away from the epididymis.
Page 51
Sperm production
Seminiferous tubules contain both Sertoli
cells & Leydig cells
Sertoli cells nourish developing sperm as
they undergo 1
st
& 2
nd
meiotic divisions
Also remove much of their cytoplasm
64 days from last mitotic division
leave
seminiferous tubule
Leydig cells: cholest.
P
testosterone
(T)
Similar to thecal cells in females
Page 52
Sperm then go to the epididymis.
~ 1 week to work their way through it
Become capable of moving, also more
concentrated
~ 150 million sperm produced per day!!
Very few will be lucky enough to contribute
their genes to the next generation!
Epididymis and vas deferens are
storage sites for sperm.
Sperm production