Male reproductive system organs

Male reproductive system organs

Introduction : The delicate gonads of the male lie outside the abdominal cavity as these cannot withstand the temperature of the abdominal cavity. The epidermis carrying the spermatozoa starts from the testis and continues as the vas deference. The vase deference after a course in the scrotum enters the anterior abdominal wall, crosses the pelvic brim to enter the anterior part of pelvic cavity. Seminal vesicles are placed at the vase of urinary bladder. The duct of seminal vesicle unites with vas deference to from the ejaculatory duct which opens into the prosthetic urethra. Prostate is an important gland; for its secretions help in maturation of the
sperms. It undergoes a lot of changes from birth to old age and is very vulnerable to malignant changes. Cancer prostate can metastasis even to cranial cavity as the prosthetic venous plexus. The male reproductive organs include the external and internal genitalia. The external genitalia are the penis and the scrotum. The internal genitalia on each side are the epidermis, the duct deference, the seminal vesicle, the ejaculatory ducts, the prostate, and the male urethra.

Ducts deferens

The ductus deferens is also called the vas deferens or the deferent duct. The ductus deferens is a thick- walled, muscular tube which transmits spermatozoa from the epididymis to the ejaculatory duct. It feels cord-like at the upper lateral part of scrotum.Ductus deferens has a narrow luman except at the terminal dilated part called the ampulla. The ductus deferens is about 45 cm long when straightened. The prostate lies in the lesser pelvis, below the neck of the urinary bladder, behind the lower part of the pubic symphysis and the upper part of the pubic arch, and in front of the ampulla of the rectum. It resembles an inverted cone, measuring about 4 cm transversely at the base, i.e. width 3 cm vertically, i.e. lenth, and 2 cm nteroposteriorly or thickness. It weight about 8 g.

Gross features 

 The prostate comprises an apex directed downwards ; a base;  four surfaces, anterior, posterior and two inferolateral.The apexis directed downwards surrounds the junction of prostatic and membranous parts of posterior urethra. It is separated from the anal canal bu the perineal body. The base is directed upwards, and is structurally continuous with the neck of the bladder. The junction is marked by a circular groove which lodges venules of the vesical and prostatic plexuses. The anterior surface is narrow and convex from side to side. It lies 2 cm behind the pubic symphysis, with retropubic fat intervening. Its upper part is connected
to the pubic bones by the puboprostatic ligaments. The lower end of  this surface is pierced by the urethra. The lower end of urethra emerges from this surface anterosuperior to the apex of gland. This surface is composed of fibrous tissue. The posterior surface is triangular in shape. It is flattened from side to side and convex from above downwards. It is separated from the rectum by the fascia of denonvilliers which is the obliterated rectovesical pouch of peritoneum. Near its upper border it is pierced on each side of the median plane by the ejaculatory duct. This surface lies 4 cm from the anus, and can be easily palpated on digital exa-
mination through the rectum. The inferolateral surfaces are related to this side walls of pelvis. The anterior fibres of the levator ani enclose the gland in pubourethral sling. They are separated from the muscle by a plexus of veins embedded in its sheath.                  

Blood supply and Nerve supply

The prostate is supplied by branches from the inferior vesical, middle rectal and internal pudendal arteries. Branches of these arteries from a large outer or subcapsular plexus, and a small inner or periurethral plexus. The greater part of the gland is supplied by the subcapsular plexus. The veins from a rich plexus around the sides and basa of the gland. The plexus communicates with the vesical plexus and with the internal pudendal vein, and drains into the vesical and internal iliac veins. Valveless communications exist between the prostatic carcinoma can spread to the vertebral column and to the skull. The prostatic plexus of nerves is derived from the lower part of the inferior hypogastric plexus. It contains thick nerves and numerous large ganglia. In
addition to the prostate and structures within it, the plexus also supplies the seminal vesicles, the corpora cavernosa, the corpus spongiosum, the membranous and penile parts of the urethra, and the bulbourethral glands. The prostate is supplied by both sympathetic and parasympathetic nerves. The gland contains numerous end-organs, impulses from which are relayed to the lower three lumbar and upper sacral segments. Secretions of the prostate are produced and discharged after stimulation of both the parasympathetic and sympathetic nerves.

Age changes in prostate
At birth the prostate is small in size, and is made up mainly of stroma in which a simple duct system embedded. During the first 6 weeks afterbir the epithelium of the ducts and of the prostatic undergoes hyperplasia and squamous inetaplasia, under the stimulation of maternal oestrogens. There after, up to the age of 9 years changes are negligible. Between 9 and 14 years, the duct system becomes more elaborate by formation of side buds, and the gland slowly increases in size. At puberty the male hormones bring about rapid changes in the gland. In about one year it becomes double its prepubertal size dur to rapid growth of
the follicles and condensation and reduction of the stroma. From 20 to 30 years there occurs marked proliferation of the glanular epithelium into the luman of the follicles, making them irregular. From 30 to 45 years the size of the prostate remains constant, and involution starts. The epithelial infoldings gradually disappear and amyloid bodies increase in number. After 45 to 50 years the prostate is either enlarged called the benign hypertrophy or reduced in size called the senile atrophy.

Histology and Development : Prostate is a fibromuscular glandular organ. The stroma comprises collagen fibres and smooth fibres. The columnar epithelium of acini is folded. The lumen may contain small colloid masses called amyloid bodies. The prostatic urethra, lined by transitional epithelium mayalso be seen. Prostate develops from a series of endodermal buds from the lining of primitive urethra and the adjacent portion of urogenital sinus, during first 3 months of intrauterine life. The surrounding mesenchyme condenses to from the stroma of the gland. Prostatic utricle develops in the region of mullerian tubercle similar to uterus or vagina in females. The central zone of glandular tissue is of wolfian duct system.        
                       
Clinical anatomy : Vasectomy or removing part of the vas deferens is one of the commonest operations being done for purposes of family planning. It is a minor operation which is done under local anaesthesia. A median incision is made in the upper part of the scrotum, just below the penis. Through this incision both the deferent ducts are operated. A short segment of each duct is excised,and the cut ends are ligated . The operation is reversible, and recanalisation can be doneif required . After vasectomy, the testis continue to produce the hormones normally to maintain the male characteristics. The hormones pass out through the veins. Sperms are present in a few ejaculations after vasectomy, as it is an emptying process. Newly formed sperms are destroyed in the epididymis and are removed by phagocytosis. After 50 years of age the prostate is often enlarged due to benigh hypertrophy or due to the formation of an adenome. This causes retention of urine due to distortion of the urethra. Enlargement of the median lobe not only projects into bladder,but forms a sort of valve over the internal urethral orifice, so that more patient strains, more it obstructs the passage. Urine passes when the patient relaxes. Digital examination of the rectum is very helpful in the diagnosis of an enlarged prostate. Removal of such a prostate called prostatectomy relieves the urinary obstruction. During removal, the enlarged gland is enucleated, leaving behind both the capsules and venous plexus between them.The prostate can be removed through bladder (transvesical ), through prostatic capsule (retropubic), or through perineum and fascia of denonvilliers (perineal approach) or through urethra. Inflammation of the prostate is referred to as prostatitis. It may be acute or chronic. Acute prostatitis is secondary to gonococcal urethritis and chronic prostatitis may be secondary to tuberculous infection of epididymis, seminal vesicles and the bladder.