Explain male sex organ (penis) and support with a diagram of human sperm .
Answers
Explanation:
Male reproductive system has two parts viz. the reproductive organs and accessory glands. The main organ or male gonad is testis which is present in the scrotum.
(1) Scrotum: The scrotum is a pouch of pigmented skin arising from lower abdominal wall. Scrotum protects the testes and acts as thermoregulator.
(2) Testes: Testes are primary sex organs that are extra-abdominal in position. There are about 200 to 300 lobules in each testis which are composed of germinal epithelial cells. Seminiferous tubules consists of spermatogonia (sperm mother cells) and nurse cells or cells of Sertoil. There are interstitial cells or cells of Leydig which secrete the hormone testosterone after puberty.
(3) Vasa efferentia. : Vasa efferentia are a pair of ducts starting from the rete testis and entering in the epididymis.
(4) Epldidymis: Epididymis are paired structures showing about 6 m long highly coiled duct situated on the posterior border of each testis. It is differentiated into the following three regions. Caput epididymis which is upper wider head that receives vasa efferentia. The sperms undergo physiological maturation acquiring increased motility and fertilizing capacity. Corpus epididymis which is middle narrower body. Cauda epididymis which is a lower duct or tail. In the tail, sperms remain for short period and then enter the vas deferens.
(5) Vasa deferentia: A pair of tubular structures about 40 cm long arising from cauda epididymis are called vasa deferentia.
(6) Ejaculatory duct: Duct of vas deferens and a duct of seminal vesicle are the ejaculatory ducts. Both ejaculatory ducts open into urethra near the prostate gland. Seminal fluid containing sperms are carried by ejaculatory duct to the urethra.
(7) Urethra: The urethra has three parts, viz., prostatic urethra, membranous urethra and penile urethra. Urethra carries both urine and semen.
(8) Penis: Penis is the copulatory organ used for insemination or deposition of sperms in female genital tract. Through the length of penis passes the urethra.
Accessory sex glands:
(1) Seminal vesicles: The seminal vesicles are two small fibromuscular pouches present on the posterior side of the urinary bladder. They have seminal ducts which join with vas deferens and form ejaculatory ducts. Seminal fluids secreted by seminal vesicle which forms about 60% of the total volume of the semen.
(2) Prostate gland: It secretes prostatic fluid which is about 30% of total volume of semen. The prostatic fluid is a whitish and alkaline liquid. The prostatic secretion neutralizes the acidity of vaginal secretion.
(3) Caliper's glands (Bulbourethral-glands): Situated on either sides of membranous urethra are pea-sized Cowper's glands which secrete an alkaline viscous fluid.
