Male Reproductive - Seminiferous Tubules
-
Upload
okwirian6971 -
Category
Documents
-
view
235 -
download
0
Transcript of Male Reproductive - Seminiferous Tubules
-
8/7/2019 Male Reproductive - Seminiferous Tubules
1/11
Male Reproductive - Seminiferous Tubules
Testis. Each testis is composed of an exocrine part (seminiferous tubules) and an endocrine part
(interstitial or Leydig cells). The testis is divided into lobules by septa consisting of loose areolar
connective tissue. Several seminiferous tubules are found in each lobule, and interstitial cells are
found in the connective tissue septa surrounding the seminiferous tubules. The seminiferous tubules
are the exocrine portion of the testis producing and "excreting" spermatozoa. These tubules are
lined by a stratified epithelium that consists of the developing spermatozoa and supporting cells
(Sertoli cells). View the image below at increasing magnification to see the structure of the
seminiferous tubules and note the appearance of the stratified epithelium which lines them.
-
8/7/2019 Male Reproductive - Seminiferous Tubules
2/11
1. + low power
-
8/7/2019 Male Reproductive - Seminiferous Tubules
3/11
2. ++
-
8/7/2019 Male Reproductive - Seminiferous Tubules
4/11
3. +++
-
8/7/2019 Male Reproductive - Seminiferous Tubules
5/11
4. ++++
-
8/7/2019 Male Reproductive - Seminiferous Tubules
6/11
5. +++++
-
8/7/2019 Male Reproductive - Seminiferous Tubules
7/11
6. ++++++ high power
Seminiferous tubules. The stratified epithelium of the seminiferous tubules is composed of different
stages of developing sperm cells. Spermatogonia are stem cells located near the basement
membrane of the tubule which proliferate by mitosis. Some of the progeny cells differentiate into
sperm and move away from the basement membrane toward the lumen of the tubule. These
differentiating cells first undergo meiosis then undergo a morphological change to become
spermatozoa. Some of the progeny cells undergo mitosis again to produce more progeny cells
providing a continuous source of stem cells for the production of spermatozoa. This entire process is
described in more detail on the next page.
Examine the images below to see the following developing sperm cells: (1) spermatogonia, (2)
primary spermatocytes, (3) secondary spermatocytes, (4) spermatids and (5) spermatozoa. The third
and fourth images also show Sertoli cells.
-
8/7/2019 Male Reproductive - Seminiferous Tubules
8/11
1. Spermatogonia, Primary Spermatocytes,Spermatid
2. Primary Spermatocytes, Early Spermatids,Spermatozoa
-
8/7/2019 Male Reproductive - Seminiferous Tubules
9/11
3. Primary Spermatocytes, Secondary Spermatocytes, Spermatids, Sertoli Cells
4. Spermatozoa, Sertoli Cells
-
8/7/2019 Male Reproductive - Seminiferous Tubules
10/11
Interstitium. The interstitial tissue of the testis consists of loose areolar connective tissue containing
numerous reticular fibers which serves to support the seminiferous tubules. The interstitial cells
(Leydig cells), located in this connective tissue, are responsible for the synthesis and secretion of the
steroid hormone testosterone. The following images show the appearance of the interstitium and
Leydig cells in histological slides.
1. Leydig cells - low power
-
8/7/2019 Male Reproductive - Seminiferous Tubules
11/11
2. Leydig cells - high power
Quick checks (try these to check your understanding of the material on this page):
Which part of the testis excretes spermatozoa?
tunica albuginea
seminiferous tubules
interstitium
Sertoli cells
Which part of the testis secretes testosterone?
Sertoli cells
Primary spermatocytes
Leydig cells
Spermatids