Male Reproductive System

Male Reproductive SystemMale reproductive system consists of:1. The testes surrounded by tunica vaginalis,2. The epididymis,3. The ductus deferentes/ductus deferens,4. The accessory glands (vesicular, prostate, and bulourethral),5. The urethra, and 6. The penis surrounded by the prepuce.

Histology of Testis

•Covered by Tunica albuginea,•Convoluted Seminiferous Tubules, and• Interstitial cell/Leydig cell.

Histology of Testis-Tunica albuginea It is a solid capsule of dense connective tissue.

Consist of collagen fiber, elastic fibers and myofibroblasts.

In cat, interstitial endocrine cells (secretes testosterone) also found in the tunica albuginea.

Histology of Testis- Seminiferous Tubules

Convoluted seminiferous tubules:

Tortuous two ended loops with a diameter between 150-200 μm. The seminiferous tubules have 3 components: 1. Lamina propria 2. Somatic cells (Sustentacular, Supporting, or Sertoli,s cells) 3. Spermatogenic cells.

1. Lamina Propria of Seminiferous Tubules The lamina propria surrounds the seminiferous tubules and consists of collagen and elastic fibers.

Peritubular smooth muscle (in boar), and myofibroblast (in bull) present which cause contraction of seminiferous tubules for the ejection of spermatozoa.

Lymphocytes and monocytes are also present in the lamina propria.

2. Sertoli Cells of the Seminiferous Tubules

2. Sertoli Cells of the Seminiferous Tubules

Also known as Sustentacular cell/ Supporting cell. These cells are resting on the base of seminiferous tubules and having large nucleus with one prominanat nucleoli. The cells are irregularly outlined, elongated cells. Sustentacular cells are closely associated with the spermatocytes, andspermatids.

Function of Sertoli CellsImportant functions of Sertoli cells:• Nutritive, Protective and Supportive functions for the

spermatogenic cells.• Phagocytize regressive and spermatogenic cells.• Detached residual bodies of spermatid.• They mediate the action of FSH and testosterone on the

germ cells.• They secretes inhibin which blocks the secretion of

pituitary-FSH.

3. Spermatogenic Cells of Seminiferous Tubules

Spermatogenic cells are:1. Spermatogonia: They are sphericalcells resting on the basement memb- -rane with round one or two nuclei.The cells are located in between Serto--li cells. There are two types of sperma-togonia. Type A and Type B. Type B

undergoes mitosis and differentiatedinto primary spermatocyte.2. Primary spermatocytes, secondaryspermatocytes, and spermatids are the next generation of the spermato-gonia.

Histology of Testis- Interstitial Cell/Leydig cell

The intertubular spacecontain loose connec- tive tissue, blood and Lymph vessels,fibrocyteFree mononuclear cells, and interstitialendocrine (Leydig) cells.

Interstitial or Leydig cells of the testis• Embryologically interstitial cells develop from

mesenchymal cells.• Interstitial cells comprises 1% of the entire

testicular volume in the adult ram, 5% in the bull, and 20-30% in the boar.

• These cells found in the form of cords or clusters. The cells are spherical with large round cells, enough endoplasmic reticulum and mitochondria for the transformation of cholesterol (important component of the testosterone hormone).

Function of Interstitial or Leydig cells of the testis

• Promote normal sexual behaviour of male animals.

• Growth, maintenance, and initiate function of the male accessory glands and secondary sex characters.

• Control spermatogenesis.• General anabolic effect.

SpermatogenesisDefinition: It is the process of formation of spermatozoa from spermatogonium. Usually one mitotic and two meiotic stage occurs during the process. The sequence of event takes place by 3 successive process:1. Spermatocytogenesis: In this process spermatogonia developed into primary spermatocytes. From 1 B-spermatogonium 1 primary spermatocytes formed (by mitosis).2. Meiosis: By 2 meiotic division 1primary spermatocyte divide into 2 secondary spermatocyte and then finally into 4 haploid spermatid.3. Spermiogenesis: Transformation of spermatid into spermatozoa.

Images for Spermatogenesis

Morphology of Bull Spermatozoa

HeadNeck

Middle PiecePrincipal Piece

Tail

Spermatozoa is a single cell having nucleus (head), cytoplasm and cell membrane around the centriole and axonema (tail).It consist of Head, Neck, and Tail. Neck is short. Tail is further divided into: Middle piece, Principal piece and End piece. Middle piece is characterized by the presence of Mitochondria for energy during motility. The principal piece is the longest. Tail is the terminal part.

Histology of EpididymisThe ductus epididymis is extremely tortuousand coiled. In bull and boar the length is 40 meter, and in stallion it is 70 meter in length. Epididymis is lined by a pseudostratified epithelium, surrounded by a small amount ofLoose connective tissue and circular smooth muscle fiber. Two cell types are present: tall columnar ciliated cells (principal cells) and short absorptive cells. Function:Storage and maturation of the spermatozoa.

Histology of Ductus Deferens The mucosa is lined byPseudostratified columnar epithelium. Lamina propria consistof loose connective tissue. Propria submucosa inStallion, bull and boar have circular, longitudinal, and obliqueSmooth muscle layers.

The terminal portion of the ductus deferens contains simple branchedTubulo-alveolar gland in the proria-submucosa. In the stallion, bull, and ram these glands occupy the entire propria-submucosa surrounded by smooth muscle, whereas, in dog the gland is not surrounded by muscles. The gland is lined by simple cuboidal to columnar epithelium. In man no such type of gland.

Male Accessory Gland

• Male accessory glands of animals are: 1. Vesicular gland or Seminal vesicle 2. Prostate gland 3. Bulbourethral gland

Histology of Vesicular Gland

• The paired vesicular gland is a compound tubular or tubulo-alveolar gland.

• The glandular epithelium is pseudostratified with tall cell.

• Lamina propria-submucosa is continuous.

• Tunica muscularis is of smooth muscle and it is followed by tunica serosa or adventitia.

Images for Vesicular Gland of Animals

Vesicular Gland in Different Animals• Stallion Boar Ruminants

• Epithelium is Same as stallion Columnar cell Pseudostratified. • It is true vesicular. Vesicular Gland is compact. • Interlobular septa is thin Smooth The interlobular septa

irregularly arranged muscle is few is thick with predominant muscles. in the interlobular smooth muscle.

septa.

Histology of Prostate Gland• Tubulo-alveolar gland derived from the epithelium of

pelvic urethra.• Having two parts: 1. Compact or External portion (corpus

prostate), and internal portion (pars disseminate). The external portion entirely surrounds part of the pelvic urethra. The disseminate portion is located in the propria-submucosa of the pelvic urethra.

• The secretory tubules/alveoli is lined by a simple cuboidal or columnar epithelium.

Histology of Prostate Gland-cont• Occasionally, concentriclly laminated concretions of

secretory materials are found in the tubules of the alveoli.• The prostate is surrounded by a capsule of dense irregular

connective tissue that contain many smooth muscle.• From the capsule connective tissue and smooth muscle

enters the gland and divide the gland into lobes and lobules. Therefore aound the small secretory unit there is connective tissue and smooth muscle, contraction of which empties the secretory materials into the duct system.

• •

Images for Prostate Gland of Animals

Prostate Gland in Different Animals• Carnivors Stallion Ruminants Boar • External portion is Only external The external The well developed portion is portion is external and separated into present. No absent. Internal portion 2-lobes. The Internal internal gland. portion is well is plate portion consist of few developed and like and glandular lobules. encircles the internal uretra. portion is well developed.

Histology of Bulbourethral Gland• Paired gland, and located dorsolaterally from the bulbar portion of

the urethra. It is compound tubular (boar, cat, and buck) or tubulo-alveolar (stallion, bull, ram). It is absent in dog.

• The secretory portion of the gland are lined with a tall simple columnar epithelium and occasional basal cells.

• The gland is covered by a fibroelastic capsules with striated muscle.

• Trabeculae extending from the capsule into the gland and devide it into many lobes and lobules. Trabeculae consists of both smooth and striated muscle.

Images for Bulbourethral Gland of Animals

Bulbourethral Gland in Different Animals

• Carnivors Stallion Ruminants

In the cat, the The gland Same as sinus like duct is completely stallion and short, narrow surrounded by unbranched tubular bulbocavernous end piece. Muscle.

Histology of Penis of Different Animals• Penile muscles are two types:• Corpus cavernosum penis and• Corpus spongiosum.Corpus cavernosum penis muscle: Paired muscle

originates from ischiatic tuberosities and situated dorsal to the urethra of animals.

Covered by tunica albuginea of connective tissue. Trabeculae enters the muscle as numerous septa. There are numerous cavernous space within this

muscle, lined by endothelium, and are filled up by blood during erection.

Histology of Penis of Different Animals- cont.

• Corpus spongiosum penis muscle: This muscle is situated around the urethra.Note please:• Corpus cavernosum muscle is thicker and spacious than

the spongiosum muscle.• In the horse Corpus cavernosum muscle is more thicker

and spacious than the ruminants.• In the dog os penis (bones of the penis) is present in

the glans.• In the cat the glans is provided with the spines.

Mechanism of Erection of Penis• Erection of penis depends on the pheromonal (in insect and lower

animals), psychological, neurological, and blood flow into the penis.

• Relaxation of the muscles of helicine arteries of the penis causes increased blood flow into the penis and cavernous spaces resulting increases in the length of penis, which compress the veins and subsequently decreases the outflow resulting persistent of the erection of penis until semen ejaculation.

• Detumescence is initiated by contraction of the musculature of the helicine arteries and thus decrease in arterial inflow causes the penis to return to flaccid state.

• High sugar and cholesterol level of the blood decrease inflow of blood resulting erectile dysfunction of man and animals.