Male

The Male Reproductive System

The male reproductive system consists of:-
Two testes Genital ducts Male accessory glands Penis (copulatory organ)

The male genital system. The testis and the epididymis are shown in different scales than the other parts of the reproductive system. Note the communication between the testicular lobules

Low magnification of seminiferous tubules and interstitial cells

Part of a seminiferous tubule with its surrounding tissues. The seminiferous epithelium is formed by 2 cell populations: the cells of the spermatogenic lineage and the supporting or Sertoli cells

FUNCTIONS OF SERTOLI CELL

Mechanical support, protection , nutritional regulation of the developing germ cells and release of spermatozoa.PhagocytosisSecretion1.Fluid for sperm transport2.Anrogen –binding protein(ABP)3.Inhibin

BLOOD-TESTIS BARRIER

The occluding(tight) junctions between adjacent Sertoli cells are responsible for this barrier, which is of importance in protecting the male germ cells against an autoimmune reaction. This divides the epithelium of seminiferous tubules into: 1.Basal compartment 2.Adluminal compartment


The Sertoli cells form the blood-testis barrier. Neighbor Sertoli cells are attached by occluding junctions that divide the seminiferous tubules into 2 compartments and impede the passage of substances between both compartments. The basal compartment comprises the interstitial space and the spaces occupied by the spermatogonia. The adluminal compartment comprises the tubule lumen and the intercellular spaces down to the level of the occluding junctions (OJ). In this compartment are spermatocytes, spermatids, and spermatozoa. Cytoplasmic residual bodies from spermatids undergo phagocytosis by the Sertoli cells and are digested by lysosomal enzymes. The myoid cells surround the seminiferous epithelium

SPERMATOGENESIS

1.Spermatocytogenesis(mitosis) 2.Meiosis 3.Spermiogenesis


Diagram showing the clonal nature of the germ cells. Only the initial spermatogonia divide and produce separate daughter cells. Once committed to differentiation, the cells of all subsequent divisions stay connected by intercellular cytoplasmic bridges. Only after they are separated from the residual bodies can the spermatozoa be considered isolated cells. (Modified and reproduced, with permission, from Bloom W, Fawcett DW: A Textbook of Histology, 10th ed. Saunders, 1975.)

Seminiferous Tubules

Primary Spermatocytes
Sperm
Spermatids
Sperm

Seminiferous TubulePrimary spermatocytesSpermatidsArrow – sertoli cell Sperm

SEM of a seminiferous tubule
Sg, spermatogonia; Sc, spermatocytes; Se, Sertoli cells; Ta, sperm tails

Diagram of Spermiogenesis

Top: The principal changes occurring in spermatids during spermiogenesis. The basic structural feature of the spermatozoon is the head, which consists primarily of condensed nuclear chromatin. The reduced volume of the nucleus affords the sperm greater mobility and may protect the genome from damage while in transit to the egg. The rest of the spermatozoon is structurally arranged to promote motility. Bottom: The structure of a mature permatozoon.

TEM of developing sperm head

AC – acrosome; PM – plasma membrane

TEM of developing sperm midpiece

Mi – mitochondria; He – head; Cp – centriole; Cf/Pf – microtubules of flagellum

TEM of crossections through sperm tails

Note the 9 + 2 arrangement of microtubules

SEM of a mature sperm cell

The disposition of mitochondria in the middle piece is an example of a concentration of these organelles in sites related to cell movement and high energy consumption. Movement of the flagellum is a result of the interaction among microtubules, ATP, and dynein, a protein with ATPase activity.


KARTAGENER’S SYNDROME Is characterized by infertility in men because their spermatozoa are immotile. It is due to lack of dynein or other proteins required for flagellar motility in patients spermatozoa. Is usually coincident with chronic respiratory infections, since a similar deficiency exists in the ciliary axonemes of respiratory epithelial cells.

Interstitial or Leydig Cells (arrows)

Leydig Cells


Epithelium of seminiferous tubules surrounded by myoid cells. The spaces between the tubules contain connective tissue, blood and lymphatic vessels, and interstitial cells. PT stain. Medium magnification.

Diagram of the ultrastructure of a hypothetical steroid-secreting cell. Note the abundance of the smooth endoplasmic reticulum (SER), lipid droplets, Golgi complex, and lysosomes. The numerous mitochondria have mainly tubular cristae. They not only produce the energy necessary for the activity of the cell but are also involved in steroid hormone synthesis. Rough endoplasmic reticulum (RER) is also shown.

Electron micrograph of a section of an interstitial cell. There is abundant smooth endoplasmic reticulum as well as mitochondria. Medium magnification.

Hypophyseal control of male reproduction. Luteinizing hormone (LH) acts on the Leydig cells, and follicle-stimulating hormone (FSH) acts on the seminiferous tubules. A testicular hormone, inhibin, inhibits FSH secretion in the pituitary. ABP, androgen-binding protein. (Modified and reproduced, with permission, from Bloom W, Fawcett DW: A Textbook of Histology, 10th ed. Saunders, 1975.)


1. Hormones 2.Temperature 3. Malnutrition, alcoholism, and the action of certain drugs lead to the alterations in spermatogonia, with a resulting decrease in production of spermatozoa.

Testicular temperature is almost 35oC and is controlled by several mechanisms:

A rich venous plexus (the pampiniform plexus) surrounds each testicular artery and forms a countercurrent heat-exchange system that is important in maintaining testicular temperature. Evaportation of sweat from the scrotum, which contributes to heat loss. Contraction of cremaster muscles of the spermatic cords, which pull the testes into the inguinal canals, where their temperature can be increased.


CRYPTORCHIDISIM
Failure of descend of the testes into the scrotum. Results in sterility because the temperature of the undescended testes inhibits spermatogenesis. Does not affect testosterone production. Is associated with a much higher incidence of testicular malignancy.

Male Genital Ducts

The male genital system. The testis and the epididymis are shown in different scales than the other parts of the reproductive system. Note the communication between the testicular lobules

Low magnification – The entire testis Epididymis

Seminiferous tubules
Rete Testis

Low maginfication of the Rete Testis

Ductuli Efferentes

Ductuli Efferentes

The highly coiled ductus epididymidis, sectioned several times. Its wall is made of a pseudostratified columnar epithelium surrounded by connective tissue and smooth muscle. PSH stain. Medium magnification. Inset: Higher magnification of the epithelial cells with their long microvilli (stereocilia).

The Epididymis – pseudostratified with stereo cilia Smooth Muscle

Low magnification of the Spermatic Cord with the Ductus Deferens (DD)

The Ductus Deferens or Vas Deferens

Smooth Muscle

Lining of the Vas Deferens

Pseudostartified columnar with stereo cilia

Accessory Genital Glands

The male genital system. The testis and the epididymis are shown in different scales than the other parts of the reproductive system. Note the communication between the testicular lobules

Low magnification of the entire Seminal Vesicle

Seminal Vesicle
Smooth Muscle

Epithelial lining of the Seminal Vesicle

Organization of the prostate gland. The prostate secretes and stores a significant contribution to the seminal fluid that is released at ejaculation. It consists of 30–50 branched tubuloalveolar glands organized into three layers, shown here schematically. Around the prostatic urethra is the transition zone which contains the mucosal glands. Surrounding most of that zone is the intermediate central zone, which contains the submucosal glands. The outermost and largest layer is the peripheral zone, which contains the most numerous main glands. Glands of all the layers contribute to the prostatic secretion.

Low magnification of the Prostate Gland

Low magnification of the Prostate Gland with concretions

High magnification of the Prostate Gland with concretions

Transverse section of the penis

The Penis


Seminal Fluid (Semen): Consists of spermatozoa together with the fluid (seminal plasma) in which they are suspended. The seminal plasma is a product of the accessory genital glands together with a minor contribution supplied by the genital ducts. The seminal plasma serves as an energy source and vehicle for the spermatozoa. Semen is a whitish, opaque fluid containing about (50-150) million spermatozoa/1ml. The average volume of the human ejaculate is about 3ml containing 200-300 million sperms.


Ejaculation: is the process by which semen is expelled. The sequence of events includes: Lubrication of the urethra by the secretions from bulbourethral and urethral glands. Discharge of the prostate. Forceful contractions of the ductus epididymidis and ductus deferens to expel the spermatozoa. Finally, discharge of the seminal vesicles.