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Histology Of PROSTATE GLAND

The prostate is an exocrine gland of the male reproductive system in most mammals and some invertebrates. It differs considerably among species anatomically, chemically, and physiologically. The word prostate comes from Ancient Greek προστάτης, prostátēs, meaning "one who stands before", "protector", "guardian".[1] Anatomically, the prostate is found below the bladder, with the urethra passing through it. It is described in gross anatomy as consisting of lobes, and in microanatomy by zone. It is surrounded by an integral fibromuscular band,[2] often referred to as the capsule.[3][4] The prostate is sheathed in the muscles of the pelvic floor, which contract during ejaculation. The prostate contains some smooth muscles that help expel semen during ejaculation. The function of the prostate is to secrete a fluid which contributes to the volume of the semen. This prostatic fluid is slightly alkaline, milky or white in appearance, and in humans usually constitutes roughly 30% of the volume of semen, the other 70% being spermatozoa and seminal vesicle fluid.[5] The alkalinity of semen helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm.Structure The prostate is a gland of the male reproductive system. In adults, it is about the size of a walnut,[6] and has an average weight of about 11 grams, usually ranging between 7 and 16 grams.[7] The prostate is located in the pelvis. It sits below the urinary bladder and surrounds the urethra. The part of the urethra passing through it is called the prostatic urethra, which joints with the two ejaculatory ducts.[6] The prostate is covered in a surface called the prostatic capsule or prostatic fascia.[4] The internal structure of the prostate has been described using both lobes and zones.[8][6] Because of the variation in descriptions and definitions of lobes, the zone classification is used more predominantly.[6]Blood and lymphatic vessels The prostate receives blood through the inferior vesical artery, internal pudendal artery, and middle rectal arteries. These vessels enter the prostate on its outer posterior surface where it meets the bladder, and travel forward to the apex of the prostate.[4] Both the inferior vesicle and the middle rectal arteries often arise together directly from the internal iliac arteries. On entering the bladder, the inferior vesical artery splits into a urethral branch, supplying the urethral prostate; and a capsular branch, which travels around the capsule and has smaller branches which perforate into the prostate.[4] The veins of the prostate form a network – the prostatic venous plexus, primarily around its front and outer surface.[4] This network also receives blood from the deep dorsal vein of the penis, and is connected via branches to the vesical plexus and internal pudendal veins.[4] Veins drain into the vesical and then internal iliac veins.[4] The lymphatic drainage of the prostate depends on the positioning of the area. Vessels surrounding the vas deferens, some of the vessels in the seminal vesicle, and a vessel from the posterior surface of the prostate drain into the external iliac lymph nodes.[4] Some of the seminal vesicle vessels, prostatic vessels, and vessels from the anterior prostate drain into internal iliac lymph nodes.[4] Vessels of the prostate itself also drain into the obturator and sacral lymph nodesMicroanatomy Micrograph of benign prostatic glands with corpora amylacea. H&E stain. The prostate consists of glandular and connective tissue.[6] Tall column-shaped cells form the lining (the epithelium) of the glands.[6] These form one layer or may be pseudostratified.[4] The epithelium is highly variable and areas of low cuboidal or flat cells can also be present, with transitional epithelium in the outer regions of the longer ducts.[12] The glands are formed as many follicles, which in drain into canals and subsequently 12–20 main ducts, These in turn drain into the urethra as it passes through the prostate.[4] There are also a small amount of flat cells, which sit next to the basement membranes of glands, and act as stem cells.[6] The connective tissue of the prostate is made up of fibrous tissue and smooth muscle.[6] The fibrous tissue separates the gland into lobules.[6] It also sits between the glands and is composed of randomly orientated smooth-muscle bundles that are continuous with the bladder.[13] Over time, thickened secretions called corpora amylacea accumulate in the gland.