Anatomy and Human Biology 2214 M. Hall

August 24, 2009

MALE REPRODUCTIVE SYSTEM LAB

Objectives: You should be able to identify the following structures on your slides:

Testis
tunica albuginea
interstitial (Leydig) cells
seminiferous tubules
Sertoli cells
spermatogonia
primary spermatocytes
early spermatids
late spermatids
Epididymis
efferent ducts
duct of the epididymis
stereocilia
basal cells
sperm in lumen
Spermatic cord
vas deferens
pampiniform plexus
skeletal muscle /
Seminal vesicle
variable epithelium
mucosal folds
muscle layer
Prostate gland
urethra
glands
prostatic concretions
muscular stroma
Penis
corpus cavernosum
corpus spongiosum
erectile tissue
cavernous sinuses
tunica albuginea
urethra
Clitoris
erectile tissue
cavernous sinuses
tunica albuginea

The male reproductive system consists of the testes, a

series of ducts and glands and the penis for conveying

the sperm to the female reproductive tract. Refer to this

diagram for the locations of the various organs and the

orientations of the various slides of the male reproductive

system. .

Slide Descriptions

67 Testis (H&E) The testis has two functions; 1. to produce the male gametes (sperm) and

2. to produce the steroid hormone testosterone.

Hold the slide up to your eye. Note the eosinophilic outer capsule, (tunica albuginea) and the more purplish interior containing the seminiferous tubules. To one side you will note the cross-section of the epididymis lying outside of the tunica albuginea. Locate these structures under low power. Note especially the many sections through seminiferous tubules with their complex stratified epithelium.

Examine the cells of the seminiferous tubule. First identify the Sertoli cells. You can recognize them, using the 40X objective, by their large pale-staining, irregular-shaped oval nuclei and prominent nucleoli. Next, examine the spermatogenic cells. Spermatogonia are the mitotically active germline cells. They lie on the basement membrane and their nuclei are oval or circular. They divide (mitotic division) and give rise to primary spermatocytes. Primary spermatocytes are easy to recognize because of the large size of their nuclei and their prominent condensed chromosomes. Primary spermatocytes divide (first meiotic division) to yield a pair of secondary spermatocytes. These rapidly divide (second meiotic division) to give rise to spermatids, so don’t bother trying to find them.

Spermatids show an amazing range of appearances as they differentiate, going from what look like normal (albeit small) cells to structures that look like mature sperm. Until they are released, spermatids have an intimate relationship with Sertoli cells, anatomically and physiologically. Even the most mature-looking should be called spermatids since they do not become spermatozoa (= sperm) until they are released from the testis and pass into the epididymis.

D-66 Testis (FeH) This section has been cut thin and stained with iron-hematoxylin to bring out cytological detail. Use it to review the nuclear changes that occur during spermatogenesis. It shows especially well that seminiferous epithelium is a mosaic of patches of cells in different stages of development.

D-66 is also an excellent slide for observing interstitial cells (= Leydig cells). These cells lie in clusters in the connective tissue between the seminiferous tubules. They are the source of testosterone. The cells are plump, with round open nuclei and cytoplasm that looks foamy due to numerous droplets of lipid.

D-69 Epididymis (H&E) The epididymis is made up of two sets of ducts encased in a connective tissue capsule. A dozen or so efferent ducts drain the testis through the rete testis and coalesce into the single larger duct of the epididymis. Both types of ducts are highly convoluted. You can distinguish the two by holding the slide up to the light and noting the size of the tubules at the two ends of the epididymis. Both types of tubules are lined by pseudostratified epithelium, but of distinctive appearances.

The efferent ducts are distinguishable by the irregular contour of their lumens. The pseudostratified epithelium is composed of short secretory and tall ciliated cells. The two cell types tend to cluster to give a wavy appearance to the lumenal surface. The tubule is surrounded by a small number of poorly differentiated smooth muscle cells.

The epithelium of the duct of the epididymis is tall with a uniform thickness. It has two cell types, tall columnar cells and cuboidal basal cells. The tall cells have very long, non-motile, branching cell processes, called stereocilia, to increase the apical surface area tremendously. Non-motile sperm are stored in this duct and in its extension called the vas deferens. You can see aggregations of sperm in some cuts through the duct of the epididymis.

The lamina propria around the duct of the epididymis has a small amount of smooth muscle, fibroblasts and capillaries. The circular arrangement of these cells is evident. As the duct proceeds down to the tail of the epididymis, the amount of smooth muscle in its wall increases to finally develop a huge well organized layer where it becomes the vas deferens. Slide D-69 shows two or three cuts through the tail of the epididymis soon before it turns into the vas deferens. The amount of smooth muscle in them has increased considerably. During ejaculation this muscle layer contracts in peristaltic waves. Sperm that are far enough down in the epididymis or are already in the vas deferens are swept along and become part of the ejaculate. Those in the upper part of the duct of the epididymis (where the smooth muscle layer is poorly developed) will have to wait for another day (or another night?).

D-65 Spermatic cord (H&E) The spermatic cord connects the testes with the rest of the body. The two vas deferens pass into the body cavity as one component of the spermatic cord. They are characterized by the extraordinary amount of smooth muscle below the mucosa. This muscle is organized into three easily distinguished layers; inner and outer longitudinal, middle circular. The epithelium is similar to that of the duct of the epididymis, tall pseudostratified columnar. The mucosa of this duct is thrown into one or several longitudinal folds, to allow the lumen to expand during ejaculation.

In addition to the vas deferens, the spermatic cord carries the vascular and neural supply to the testis, and some longitudinally disposed striated muscle fibers. The arteries are particularly prominent and arranged to form a counter current heat exchange with the veins to cool the blood before it reaches the testis. This collection of veins is called the pampiniform plexus. The veins are muscular and not that easy to distinguish from the arteries.. All of these structures are wrapped up in a dense connective tissue sheath, only partly preserved here.

D-72 Seminal vesicle (H&E) The seminal vesicle contributes an important component of semen. It is a simple tubular gland about ten centimeters long coiled up in a corkscrew fashion. On your slides it is sectioned several times. The epithelial cells (pseudostratified columnar/cuboidal) lining it are secretory, and the lumen has a storage function. Three notable features of the gland are: 1.The large lumen in which the secretion is stored as it accumulates between ejaculations. 2. The mucosa is elaborated into an amazing and beautiful set of folds which greatly increase the area of the secretory epithelium. 3. A very well developed muscularis layer

The activity of the gland and the appearance of the epithelium are controlled by the level of testosterone in the blood and thus vary with the age of the individual.

D-70 Prostate gland (H&E) The prostate gland is actually a large collection of glands of various sizes. A secretory epithelium lines both the secretory alveoli and the ducts, so it is difficult to distinguish the two. The prostate surrounds the urethra which has a distinctive crescent-shaped cross section. The ducts of the main prostatic glands empty into the urethra at the cusps of the crescent. If you look in this region you can see sections through some of these ducts. Confirm that the urethra is lined with transitional epithelium. Also, note the great amount of smooth muscle in the connective tissue between the glands, a characteristic of this organ. It can squeeze down the whole gland rapidly during ejaculation.

The glandular part of the prostate somewhat resembles the seminal vesicle. However, the two glands are fundamentally different in morphology. The seminal vesicle is a hollow tube with elaborate mucosal projections. The prostate has compound alveolar glands (remember the bunch of grapes analogy) embedded in a dense muscular connective tissue. The epithelium is pseudostratified columnar in young males and regresses to simple cuboidal in the elderly (please, not “old men”!) Another characteristic feature of the prostate is the presence of insoluble prostatic concretions. Concretions increase in number and size with age but are considered to be a “normal” feature of the prostate, since they cause no medical problems. They can be useful in confirming the identification of a section of prostate tissue.

D-71 Penis (H&E) Hold this slide up to the light. The penis consists of three cylindrical masses of erectile tissue. Two corpora cavernosa lie side by side. A single corpus spongiosum runs ventrally and contains the urethra. The urethra has a flattened lumen. The corpus spongiosum expands distally to form the glans penis. A dense fibrous coat, the tunica albuginea, surrounds each corpus. This is important in maintaining the erection as it cuts off blood flow out of the penis during erection.

The erectile tissue itself comprises a network of large, thin-walled veins (cavernous sinuses) separated by septae of connective tissue. You can see the endothelium lining the cavernous spaces and bands of smooth muscle between them. These sinuses receive arterial blood by way of arteries which open into them.

Blood drains from the erectile tissue peripherally through progressively smaller channels into veins which traverse the tunica albuginea at an angle, so that as blood distends the cylinders of erectile tissue it pinches off its exit, helping to maintain erection.

D-62 Clitoris (H&E). The clitoris is the anatomical homologue of the more highly developed penis. Although it is a part of the female reproductive system the clitoris is most appropriately examined at the same time as its male counterpart.

Hold the slide up to the light. The orientation may be somewhat confusing. The clitoris has been sectioned obliquely; more longitudinally than transversely and sort of parallel to the overlying skin. The apical end of the organ is to the left in the picture above. A fold of skin over the clitoris forms a “hood” homologous to the foreskin of the penis. This is why the epithelium seems to be located so far from the erectile tissue.

The clitoris is composed of only two columns of erectile tissue. These are homologous to the corpora cavernosa of the male penis but have the general architecture and erectile capabilities of the corpus spongiosum. Note the small, but abundant, cavernous sinuses and the relatively thin tunica albuginea, surrounding and separating the two columns of erectile tissue. Thus the clitoris can increase in size during sexual arousal. The clitoris has no homologue of the corpus spongiosum. The urethra does not run in the clitoris; it reaches the surface behind that organ.


D-67 Testis (H & E) D-66 Testis (FeH)

D-69 Epididymis (H & E) D-65 Spermatic cord (H & E)

D-72 Seminal vesicle (H & E) D-70 Prostate gland (H & E)

D-71 Penis (H & E) D-62 Clitoris (H &E)

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