1. The Male Reproductive System

2. composed of the testes, genital ducts, accessory glands, and penis
Testes function in the production of hormones and spermatozoa.
These secretions also provide nutrients for spermatozoa
Spermatozoa and the secretions of the genital ducts and accessory glands make up the semen.

3. Testes
Each testis (testicle) a capsule of dense connective tissue, the tunica albuginea.
The tunica albuginea is thickened on the posterior side of the testis to form the mediastinum testis,
from which fibrous septa penetrate the organ and divide it into about 250 testicular lobules
The septa are incomplete,.
Each lobule is occupied by one to four seminiferous tubules that are surrounded by interstitial loose connective tissue rich in blood and lymphatic vessels, nerves, and endocrine interstitial cells (Leydig cells)
Seminiferous tubules produce male reproductive cells, the spermatozoa, whereas interstitial cells secrete testicular androgens

4. The testes develop retroperitoneally in the dorsal wall of the embryonic abdominal cavity. \
each testis carries with it a serous sac, the tunica vaginalis derived from the peritoneum.
covering the tunica albuginea on the anterior and lateral sides of the testis.

5. Seminiferous Tubules
Each tubule is a convoluted loop linked via a short, narrower segment, the straight tubule, to the rete testis, embedded in the mediastinum testis
Ten to twenty efferent ductules connect the rete testis to the head of the epididymis

6. Each seminiferous tubule is lined with a complex, specialized stratified epithelium called germinal or seminiferous epithelium
The basement membrane of this epithelium is covered by fibrous connective tissue, with an innermost layer containing flattened, smooth muscle-like myoid cells which allow weak contractions of the tubule.
The seminiferous epithelium consists of two types of cells: nondividing supporting or sustentacular cells (Sertoli cells) and proliferative cells of the spermatogenic lineage
. The part of sperm production that includes cell division through mitosis and meiosis is called spermatogenesis. The final differentiation of the haploid male germ cells is called spermiogenesis.

7. Spermatogenesis

8. Spermatogenesis
begins at puberty with a primitive germ cell, the spermatogonium, a relatively small round cell, about 12 m in diameter.
These cells are located basally in the epithelium
different stages of their development are recognized mainly by the shape and staining properties of their nuclei.
Spermatogonia with dark, ovoid nuclei act as stem cells, dividing infrequently and giving rise both to new stem cells and to cells with more pale-staining, ovoid nuclei that divide more rapidly as transit amplifying (progenitor) cells These type A spermatogonia each undergo several unique clonal divisions, and form type B spermatogonia, which have more spherical pale nuclei

10. Spermiogenesis
Spermiogenesis is the final stage in sperm production and is the process by which spermatids transform into spermatozoa
The spermatids can be distinguished by their small size (7–8 m in diameter), haploid nuclei with highly condensed chromatin, and position near the lumen of the seminiferous tubules
Spermiogenesis can be divided into three phases:
§  During the early Golgi phase,. Small proacrosomal vesicles accumulate in the Golgi apparatus and subsequently coalesce to form a single membrane-limited acrosomal cap close to one end of the nucleus The centrioles migrate to a position near the cell surface and opposite the forming acrosome. One centriole acts as a basal body, serving to organize the axoneme of the flagellum.
§  During the acrosome phase, the acrosomal cap, or acrosome, spreads to cover about half of the condensing nucleus. The acrosome is a specialized type of lysosome containing several hydrolytic enzymes, including hyaluronidase, neuraminidases, acid phosphatase, and a trypsin-like protease called acrosin.
They dissociate cells of the corona radiata and digest the zona pellucida, both structures that surround the egg
This process, the acrosomal reaction, is one of the first steps in fertilization.
§         During the final maturation phase of spermiogenesis, unneeded cytoplasm is shed as a residual body from each spermatozoon and is phagocytosed by Sertoli cells. Mature sperm are then released into the lumen of the tubule.

12. Spermatid in acrosome phase of differentiation
Spermatid in acrosome phase of differentiation. the acrosome phase of spermiogenesis The flagellum (F) can be seen emerging from a basal body near the nucleus on the side opposite the acrosome.

13. Sertoli Cells
columnar or pyramidal cells that largely envelop cells of the spermatogenic lineage
Their bases adhere to the basal lamina and their apical ends frequently extend into the lumen of the seminiferous tubule
Lateral membrane has many infoldings.
Apical membrane has many foldings.
The elongated nucleus, which can be triangular in outline, often exhibiting very little heterochromatin
Cytoplasm: many inclusions of unknown function (crystalloids of Charcot Böttcher).

14. Sertoli Cells
tight occluding junctions between the basolateral membranes of adjacent Sertoli cells form a blood-testis barrier in the seminiferous epithelium,
Spermatogonia lie in a basal compartment,
newly formed spermatocytes temporarily disrupt the cell adhesion molecules of the most basal junctions and move into the adluminal compartment without compromising the blood-testis barrier

15. Sertoli cells have several specific functions within the seminiferous epithelium, mostly involving the blood-testis barrier:
§  Support, protection, and nutrition of the developing spermatogenic cells.
§  Exocrine and endocrine secretion. Sertoli cells continuously secrete into the seminiferous tubules a fluid used for sperm transport in the direction of the genital ducts. Secretion of nutrients and androgen-binding protein (ABP), which concentrates testosterone to a level required for spermiogenesis, is promoted by follicle-stimulating hormone (FSH). In an endocrine manner, Sertoli cells release the steroid estradiol derived from testosterone and secrete the glycoprotein inhibin, which in a feedback loop with the anterior pituitary gland suppresses synthesis and release of FSH.
In the fetus Sertoli cells also secrete a glycoprotein called müllerian-inhibiting substance (MIS) that causes regression of the embryonic müllerian (paramesonephric) ducts; without MIS these ducts persist and become parts of the female reproductive tract.
§ Phagocytosis.   

16. Interstitial Tissue
the site of androgen production(testosteron)
During puberty, interstitial, or Leydig, cells become apparent as either rounded or polygonal cells with central nuclei and eosinophilic cytoplasm rich in small lipid droplets
Testosterone is synthesized by enzymes present in mitochondria and the smooth ER in a system similar to that of adrenal cortical cells.
testosterone secretion by interstitial cells is promoted by, luteinizing hormone (LH),
Testosterone synthesis thus begins at puberty,

17. Intratesticular Ducts
The intratesticular genital ducts are the straight tubules the rete testis, and the efferent ductules
These ducts carry spermatozoa and liquid from the seminiferous tubules to the duct of the epididymis.
straight tubules are recognized by the gradual loss of spermatogenic cells, with an initial segment in which the walls are lined only by Sertoli cells followed by a main segment consisting of cuboidal epithelium supported by a dense connective tissue sheath.
All the straight tubules empty into the rete testis, an interconnected network of channels lined with cuboidal epithelium.
The channels of the rete testis are embedded within the connective tissue of the mediastinum

18. Straight tubules and rete testis
Straight tubules and rete testis. the transition to the straight tubule (T) is characterized by many tall Sertoli cells devoid of germ cells.

19. The rete testis drains into about 20 efferent ductules
They are lined by an unusual epithelium with groups of nonciliated cuboidal cells alternating with groups of taller ciliated cells.
This gives the epithelium a characteristic scalloped appearance
The nonciliated cells absorb most of the fluid secreted by the seminiferous tubules.
This absorption and the ciliary activity create a fluid flow that sweeps sperm toward the epididymis.
A thin layer of circularly oriented smooth muscle cells is seen outside the basal lamina of the epithelium which aids movement of the sperm.

21. Excretory Genital Ducts
The epididymis, the ductus (vas) deferens, and the urethra. They transport sperm from the epididymis to the penis during ejaculation.
The duct of the epididymis is a single highly coiled tube about 4–5 m in length. Together with a connective tissue capsule and blood vessels, this long duct forms the head, body, and tail of the epididymis,
Sperm are stored in the epididymis and attain their various final characteristics including motility, membrane receptors for zona pellucida proteins, maturation of the acrosome, and ability to fertilize.
lined with pseudostratified columnar epithelium composed of rounded basal cells and columnar cell (Principal Cells) with long, branched, irregular microvilli called stereocilia.
The epithelial cells of the epididymal duct absorb water and participate in the uptake and digestion of residual bodies produced during spermiogenesis.
These cells are supported on a basal lamina surrounded by smooth muscle cells, whose peristaltic contractions move the sperm along the duct, and by loose connective tissue rich in capillaries.

22. The duct of the epididymis (DE) is enclosed by connective tissue that contain many blood vessels (V) and the connective tissue is covered by a capsule and the tunica vaginalis, section of the smooth muscle (SM) and wall of the duct shows two abundant cell types in the epithelium: the tall principal cells with stereocilia and small basal cells (B) on the basal lamina. Macrophages and intraepithelial lymphocytes are also commonly seen in the epididymal duct.

23. From the epididymis the ductus (vas) deferens, a long straight tube with a thick, muscular wall, continues toward the prostatic urethra and empties into it.
It is characterized by a narrow lumen and a thick layer of smooth muscle
Its mucosa is folded longitudinally and is lined along most of its length by pseudostratified columnar epithelium with sparse stereocilia.
The lamina propria is rich in elastic fibers and the very thick muscularis consists of longitudinal inner and outer layers and a middle circular layer.
The muscles produce strong peristaltic contractions during ejaculation which rapidly move sperm along this duct from the epididymis.

24. the ductus deferens dilates to form an ampulla of Henle in which the epithelium is thicker and more extensively folded.
the ejaculatory duct, but the muscle layers disappear beyond the ampulla.

25. Accessory Glands:
produce secretions that are added to sperm during ejaculation to produce semen and which are essential for reproduction.
The accessory genital glands are the paired seminal vesicles, the prostate, and the paired bulbourethral glands

26. seminal vesicles highly tortuous tubes about 15 cm in length.
The unusual mucosa displays a great number of thin, complex folds that fill most of the lumen ,lined with simple or pseudostratified columnar epithelial cells rich in secretory granules.
The lamina propria contains elastic fibers and is surrounded by smooth muscle with inner circular and outer longitudinal layers.
exocrine glands that produce a viscid, yellowish secretion containing fructose, citrate, inositol, prostaglandins, fibrinogen, as well as enzymes and other proteins. 70% of the ejaculate,.
The height of the seminal vesicle epithelial cells and their degree of secretory activity are dependent on adequate levels of testosterone

28. The prostate gland :
is a dense organ surrounding the urethra below the bladder. It is approximately 2 cm x 3 cm x 4 cm in size and weighs about 20 g.
The prostate is a collection of 30–50 branched tubuloalveolar glands, all surrounded by a dense fibromuscular stroma covered by a capsule.
The glands are arranged in concentric layers around the urethra: the inner layer of mucosal glands, an intermediate layer of submucosal glands, and a peripheral layer with the prostate's main glands Ducts from individual glands may converge but all empty directly into the prostatic urethra, which runs through the center of the prostate The prostate has three zones, corresponding to the glandular layers:
§The transition zone occupies about 5% of the prostate volume, surrounds the prostatic urethra, and contains the mucosal glands emptying directly into the urethra.
§The central zone occupies 25% of the gland's volume and contains the submucosal glands with longer ducts.
§ The peripheral zone occupies about 70% of the prostate and contains the main glands with still longer ducts. Glands of this area are the most common location of both inflammation and cancer.

29. The tubuloalveolar glands of the prostate are lined by a simple or pseudostratified columnar epithelium. The glands produce prostatic fluid containing various glycoproteins and enzymes. An exceptionally rich fibromuscular stroma surrounds the glands The prostate is surrounded by a fibroelastic capsule. Septa from this capsule penetrate the gland and divide it into indistinct lobes.

30. The paired round bulbourethral glands (Cowper's glands), 3–5 mm in diameter, are located in the urogenital diaphragm and empty into the proximal part of the penile urethra. Each gland has several lobules with tubuloalveolar secretory units lined by a mucus-secreting simple columnar epithelium dependent on testosterone. The septa between lobules contain smooth muscle cells. During erection the bulbourethral glandsrelease a clear mucus-like secretion containing various small carbohydrates, which coats and lubricates the urethral lining in preparation for the imminent passage of sperm

31. Penis
The main components of the penis are three cylindrical masses of erectile tissue, plus the penile urethra, surrounded by skin
Two of these cylinders—the corpora cavernosa—are placed dorsally.
The other—the corpus spongiosum—is ventral and surrounds the urethra
At its end the corpus spongiosum expands, forming the glans
Most of the penile urethra is lined with Stratified Columnar epithelium interspersed with pseudostratified columnar epithelium.
In the glans, it becomes stratified squamous epithelium continuous with that of the thin epidermis covering the glans.
Small mucus-secreting urethra glands (glands of Littre) are found along the length of the penile urethra.

32. The corpora cavernosa are covered by a resistant layer of dense connective tissue, the tunica albuginea The corpora cavernosa and the corpus spongiosum are both composed of erectile tissue, which contains a large number of venous cavernous spaces lined with endothelial cells and separated by trabeculae of connective tissue fibers and smooth muscle cells.