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| Male Reproductive System in Human |
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| Human Reproductive System |
| In human beings, sexual reproduction takes place. Sexes are separate and hence they are known to exhibit sexual dimporphism. Males have sex organs called the tetes while the females have sex organs called the ovaries. Even in the external appearance, males and females show differences. |
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| Some of the external differences are: |
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| In men: |
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| a) Presence of a beard and moustache |
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| b) Presence of Adams apple |
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| c) Well built external structure |
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| d) Absence of mammary glands |
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| In females: |
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| a) Absence of beard and moustache |
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| b) Presence of mammary glands |
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| c) High pitch voice |
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| d) Absence of Adams apple |
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| e) Small build |
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| The male reproductive system includes the following organs |
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 The testes where male sex cells (sperms) and sex hormones (testosterone) are produced. |
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 A system of ducts which carry sperms from the testes. |
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 Accessory glands associated with the duct system which contribute to the seminal fluid. |
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| Male Reproductive Organs of Man in Ventral View |
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 The copulatory organ (penis) for the transference of sperms into female body. |
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| The human male reproductive system performs two main functions namely: |
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| a) Formation of the sperms |
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| b) Transfer of sperms to the female genital tract. |
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| In man, the testes are paired oval bodies about 4 - 5 cm in length. The testes develop in the pelvic cavity but by the time the baby is born, they move out of the abdominal cavity, and lie in a pouch of skin called scrotum. The scrotum hangs between the thighs. The testes are extra - abdominal because sperms mature at a temperature slightly lower than the body temperature. The scrotal sac is filled with a fluid called hydrocoel. |
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| As the testes in humans lie outside the body within the scrotal sacs, the testes are called extra abdominal testes. |
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| The Scrotal sacs act as thermoregulators and keep the testicular temperature 2oC lower than body temperature for normal spermatogenesis. |
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| The cavity of the testes is called vaginal coelom and it is connected to the abdominal cavity through inguinal canal. |
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| Each testis is covered by a layer of white fibrous connective tissue called tunica albuginea. The testis is formed of seminiferous tubules and the interstitial cells or Leydig cells lying between them. |
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| The seminiferous tubules are situated in regions of the testes known as testicular lobules. |
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| The seminiferous tubules are long and coiled tubes, lined with a single layer of germinal epithelium or seminiferous. The germinal epithelium consists of two types of cells namely sertoli or supporting cells and spermatogenic cells. |
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| Sertolic cells are named after its discoverer Enricho Sertoli. They are elongated and pyramidal in shape with their base adhered to the basal lamina while its apical end extends into the lumen of the seminiferous tubule. |
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| The function of the sertolic cells is to provide shape and nourishment to the developing spermatogenic cells. Its cells give rise to spermatogonia from which sperms are produced and long sertoli cells which provide nourishment to the developing sperm. |
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| T.S. Testis of Mammal |
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| The interstitial cells or Leydig cells secrete the male sex hormone testosterone. |
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| Each epididymis consists of a single tightly coiled narrow tube about 6 metre long lying along the top and side of the testis and is divided into 3 parts. |
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 The head or caput epididymis connected with the seminiferous tubules. |
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 Body or middle epididymis and |
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 Tail or cauda epididymis connected with vas deferens. |
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| The epididymis serves to store sperms prior to ejaculation, and serves as a duct for the passage of sperms from testis to vas deferens or ductus deferens. |
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| It is a muscular duct which comes out of the scrotum via the inguinal canal into the ejaculatory duct. It helps in the conduction of sperms from the testes to the ejaculatory duct by peristalsis. |
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| It arises from the urinary bladder and joins the ejaculatory duct as the urinogenital canal. It opens at the tip of the penis. |
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| It is the copulatory organ formed of a mass of retractile tissue enclosed by a fibrous covering. The tip of the penis is highly sensitive and is known as glans penis. It is covered by a retractile skin fold called foreskin or prepuce. |
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| Both urine and the semen are carried out of the body through the penis. |
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| Seminal vesicles |
| These are a pair of elongated, muscular, sacculated glands present in the pelvis. These secrete viscous fluid called seminal fluid which forms much of the semen nearly 70% of it. It also contains prostaglandins, fructose, citrate, inositol, several proteins etc. which function as spermatozoa activating substances. |
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| The prostate gland is of the size of a golf ball and is spongy in texture. These are compound tubular glands situated just below the urinary bladder. It secretes a thin alkaline substance that contributes to the largest part of the semen. It increases sperm motility and provides nutrition to the sperms. |
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| These lie below the prostrate and are of the size of peas. They secrete a mucus like substance that lubricates the vagina for friction less movements of penis during copulation. |
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| Hormonal control of the male reproductive system |
| a) The hormones of the anterior pituitary gland namely LH (Leutinising hormone) or ICSH (Interstitial cell stimulating hormone) and FSH (Follicle stimulating hormone) control the functioning the male reproductive system. |
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| b) LH or ICSH from the anterior pituitary targets the interstitial cells (or Leydig cells), that lie between the seminiferous tubules, to secrete the hormone testosterone. Testosterone is essential for the production of the sperm. The release of LH is inturn-controlled by the release of GnRH (Gonodatropin Releasing Hormone) from the hypothalamus. |
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| c) Under the action of FSH and testosterone, the sertolic cells secrete an androgen bunding protein (ABP) that concentrates testosterone in the seminiferous tubules. |
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| d) FSH also acts directly on spermatogonia to stimulate sperm production. |
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| e) Sertoli cells secrete another protein called inhibin, which suppresses FSH synthesis. |
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| f) The level of testosterone, inturn has a negative feedback control on the release of GnRH from the hypothalamus, i.e., a rising level of testosterone suppresses the release of GnRH and vice versa. |
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| Puberty is the period of sexual maturity when reproductive organs become functional. |
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| It sets in between 13 - 16 years. It is characterised by the development of secondary sexual characters like growth of hair on face, chest, pubis, broadening of shoulders, and deepening of voice due to enlargement of voice box. There is an increase in height due to rapid growth of muscles and bones. The seminiferous tubules start producing the sperms. |
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