CHAPTER 18
Male Reproductive System
357
Figure 18-11A.
Stage I seminiferous epithelium.
H&E,
left
3
207;
right
3
747
Stage I seminiferous epithelium
is shown at low magnif
cation (
left
), and a detailed representation oF the region is indicated by the
box (
right
). Stage I seminiFerous epithelium is characterized by the Following: (1)
Spermatogonia
are located at the basement mem-
brane; both
type A
and
B spermatogonia
are present, although the two types are not easily distinguished in H&E stained sections.
(2) A layer oF
pachytene primary spermatocytes
is present. Although some oF these cells are near the basement membrane, they are
not in direct contact with it. (3) A prominent layer oF round, undiFFerentiated
early spermatids
has moved toward the surFace oF the
epithelium. (4) The
late spermatids
have their heads inserted deep into the epithelium.
Late spermatid
Late spermatid
in the epithelium
in the epithelium
Early spermatid
Early spermatid
Pachytene
Pachytene
spermatocytes
spermatocytes
Late spermatid
in the epithelium
Early spermatid
Pachytene
spermatocytes
Basement
Basement
membrane
membrane
Spermatogonia
Spermatogonia
Basement
membrane
Spermatogonia
Sertoli cell
Sertoli cell
Sertoli cell
A
Late spermatid
Late spermatid
on the surface
on the surface
of theepithelium
of theepithelium
Detaching
spermatozoa
on the surface
of the epithelium
Residual
Residual
bodies
bodies
Residual
bodies
Pachytene
Pachytene
primary spermatocyte
primary spermatocyte
Pachytene
primary spermatocyte
Spermatogonium
Spermatogonium
Spermatogonium
Early spermatid
Early spermatid
Early spermatid
Sertoli
Sertoli
cell
cell
Sertoli
cell
B
Figure 18-11B.
Stage II seminiferous epithelium.
H&E,
left
3
207;
right
3
747
Stage II seminiferous epithelium
is shown at low magnif
cation (
left
), and a detailed representation oF the region is indicated by the
box (
right
). The composition oF the spermatogenic cell in stage II seminiFerous epithelium is similar to that oF stage I. The most
characteristic Features oF this stage are the Following: (1)
Detaching spermatozoa
(very late spermatids) have completed diFFerentia-
tion and are in the process oF shedding their excess cytoplasm. (2) The small leFtover cytoplasmic masses that have been shed are
called
residual bodies
and are present in the luminal border oF the epithelium, beneath the heads oF the detaching spermatozoa.
(3) These detaching spermatozoa are positioned in a row on the surFace oF the epithelium ready to be released From the epithelium
into the lumen. (4)
Early spermatids
with round nuclei and pachytene primary spermatocytes are present. (5) Both
type A
and
B
spermatogonia
are present.
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