NEET Biology Notes Animal Reproduction day and Reproductive Health Male Reproduction
Male Reproduction
The male reproductive system consists of a pair of testes along with accessory ducts, glatiife and external genitalia, which are located in pelvis region of the body.
- Testes and its AnatomySeminiferous tubules are structural and functional units of testes. Seminiferous tubules are lined by germinal epithelium, which is cuboidal in nature and site of spermatogenesis. Sertoli cells are named after its discoverer, an Italian histologist Enricho Sertoli (1842-1910). These are elongated and pyramidal, which partially envelope the spermatogenic cells. These are located in seminiferous tubules, which nourish spermatozoa. These cell act as nurse cells for differentiating spermatozoa. These are also known as subtenticular cells. These are characteristics of mammalian testes. These secrete a glycoprotein hormone called inhibin, which is involved in the negative feed back control of sperm production.
fW mammals, the cells present in interstitial connective; tissue are called Leydig cells (interstitial cells). Lqydig cells are endocrine in nature. These are characteristic of testes of mammal. - Scrotal Sac
It is a pouch of pigmented skin arising from the lower abdominal wall present hanging between the legs. The temperature is lower than body temperature to nourish sperm.
Orchidectomy is the surgical removal of testes. It is also called castration.
Gubernaculum is the ligamentous connective cord (elastic cord), which connects testes to scrotal sacs posteriorly. Gubernaculum represents mesorchism. Increase of tissue fluid in scrotal sac is called hydrocoel.
Inguinal canal connects scrotal sac to abdominal cavity. Spermatic cord is an elastic cord, which passes through inguinal canal and attached with testis.
- Epididymis
Wolffian duct of embryo gives rise to epididymis in adult. Vasa efferentia arise from rete testis and conduct sperms into epididymis. Epididymis has three parts, i. e. anterior caput, middle corpus and posterior cauda epididymis where the sperm achieve maturity and motality.
4. Vas Deferens
Vas deferens is also called ductus deferens. Vas deferens or sperm duct arises from cauda epididymis, ascends to abdomen, passes over the urinary bladder and receives the duct from seminal vesicle behind the urinary bladder forming ejaculatory duct.
- Ejaculatory Duct
Ejaculatory duct passes through the prostate to open into urethra shortly after its origin from urinary bladder. The ductus epididymis, the ductus (vas) deferens and the urethra transport the spermatozoa towards the penile meatus and thus, constitute the excretory genital ducts. Surgical removal of a portion of the ductus (vas deferens) to induce infertility is called vasectomy. Vasectomy is permanent method of contraception in males.
- Urethra
It is a thick-walled muscular duct and it is a common passage for both urine and semen and called urinogenital duct. Urethra transverses and opens at the tip of the penis as the male urinogenital aperture.
- Penis
It is the copulatory organ. It is vascular, spongy and erectile structure. Penis has glans penis at tip covered with a fold of skin called prepuce. Penis contains three longitudinal columns of spongy erectile tissue, i.e. two cylinders of the corpora cavernosa, of the penis and one cylinder, the corpus cavernosum of the urethra or corpus spongiosum, which becomes filled with blood during sexual excitement. *
Penis serves sperms into the vagina of the female during sexual intercourse. Surrounding the urinogenital duct is corpus spongiosum and above it lie two corpora cavernosa. The corpora cavernosa of the penis and the urethra are covered by dense connective tissue, the tunica albuginea. Circumcision is the removal of the prepuce (foreskin) for religious or health reasons.
- Accessary Sex Gland
Different types of accessory sex glands are as follow :
- Seminal Vesicle
- Seminal vesicles (uterus masculinus) are situated behind the bladder. They are narrow, long pouches with muscular tissue on their wall.
Uterus masculinus is situated at the junction of vas deferens and prostate gland. About 70% of the semen in seminal fluid is produced by seminal vesicles. - Seminal fluid contains fructose, (energy source for sperm) citrate, inositol, prostaglandins and several proteins.
- The product of the testes (spermatozoa) and prostate gland along with the fluid from the seminal vesicle, are collectively known as semen.
- Seminal fluid has a pH of about 7.4.
- Prostate Gland
Prostate gland is a single, large gland with the size of a golf ball and is spongy in texture. Prostate gland is a collection of 30-40 tubuloalveolar glands. Prostate is situated around the first part of the urethra. It contains prostatic utricle and acini and covered by a capsule. Prostate gland secretes a thin, milky fluid that contains calcium citrate ion, phosphate ion, a clotting enzyme and a profibrinolysin called as semen.
Note
- Enlargement of prostate results in prostatitis, in which urination is difficult or impossible.
- BPH (Benign Prostatic Hypertrophy) is a medical condition, which occurs due to the increase in size of the prostatic gland.
- Untreated BPH may leads to the cancer of Prostate.
- Cowper’s Gland (Bulbourethral Glands)
Cowper’s glands are two in number and situated beneath bladder and behind the urethra. These are present in male mammals. It opens into urethra before entering into penis. These are yellow in colour. Their secretion is slightly alkaline and is produced during sexual stimulation. Its secretion acts as a lubricant for the glans penis. It also neutralises any urine in urethra. The seminal vesicles, the prostate and Cowper’s glands constitute the accessory genital glands.