352
UNIT 3
Organ Systems
Sertoli cell
Sertoli cell
Sertoli cell
Early
Early
spermatid
spermatid
Early
spermatid
Early
Early
spermatid
spermatid
Early
spermatid
Late
Late
spermatid
spermatid
Late
spermatid
Sertoli cells
Sertoli cells
Sertoli cells
Primary
Primary
spermatocyte
spermatocyte
Primary
spermatocyte
A
Chromosomes in nucleus
of primary spermatocyte
Nucleolus of Sertoli cell
Nucleus of Sertoli cell
Cytoplasm of Sertoli cell
Basal lamina of
seminiferous epithelium
Sertoli cell
Sertoli cell
Sertoli cell
Tight junction
Tight junction
between sertoli cells
between sertoli cells
Tight junction
between sertoli cells
B
Figure 18-6A.
Sertoli cells, seminiferous tubules.
H&E,
3
732; inset
3
1,603
Sertoli cells
have pale oval or irregularly shaped nuclei,
and nucleoli are often present. They are irregular colum-
nar cells with many folded cytoplasmic processes form-
ing compartments for the spermatogenic cells. They
form
tight junctions (zonulae occludentes)
with the
neighboring Sertoli cells thereby providing a blood-
testis barrier to protect spermatogenic cells from being
harmed by autoimmune reactions. Sertoli cells con-
trol hormones, nutrients, and other substances pass-
ing through the compartments and maintain the ideal
environment for
spermatogenesis
. They play important
roles in supporting, protecting, and nourishing sper-
matogenic cells as well as in secreting testicular fl
uid
(rich in fructose) to help in transporting spermatozoa
out of the seminiferous tubules. They also secrete
ABP
,
anti-Müllerian hormone
, and
inhibin
and
activin
hormones
.
Figure 18-6B.
Sertoli cell and primary spermatocyte, seminiferous epithelium.
EM,
3
7,900; inset (
color
) H&E,
3
1,005
Sertoli cells
, the only somatic cells of the seminiferous epithelium, are dynamic cells with a long list of functions in support of
spermatogenesis
. Their processes envelope and support the germ cells throughout the many stages of meiosis and spermiogenesis.
In this view, cytoplasmic extensions of the Sertoli cell (with its nucleus at the left edge) enshroud the
primary spermatocyte
that has
entered
prophase of meiosis I
and isolate it from the
basal compartment
so that it is no longer accessible to the immune system. Note
also the example of the
junctional complexes
(including
tight junctions
) that couple adjacent Sertoli cells and, thereby, establish a
controlled and specialized environment in support of the cells that are undergoing spermatogenesis. Other functions of Sertoli cells
are secretion of testicular fl
uid, concentration of androgens, and phagocytosis of the residual bodies jettisoned by late spermatids as
they complete spermiogenesis.
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