MALE AND FEMALE REPRODUCTIVE SYSTEM

HUMAN REPRODUCTION

 

THE MALE REPRODUCTIVE SYSTEM.

·         Located in the pelvis region.

·         Male reproductive system includes

o    A pair of testes.

o    Accessory ducts.

o    Accessory glands.

o    External genitalia

Testes:

·         Located outside the abdominal cavity within a pouch called scrotum.

·         Scrotum provides low temperature required for spermatogenesis.

·         Each testis is about 4 to 5 cm length and 2 to 3 cm width.

·         Each testis has about 250 compartments called testicular lobules.

·         Each lobule contains one to three seminiferous tubules.

·         Seminiferous tubules lined by male germ cells and Sertoli cells.

·         Male germ cell undergoes meiosis and produce sperm.

·         Sertoli cells provide nutrition to the germ cell and the sperm.

·         In between the seminiferous tubule there is interstitial cell or Leydig cell.

·         Leydig cells produce testicular hormones called androgen (testosterone).

Accessory ducts:

·         Includes rete testis, vasa efferentia, epididymis and vas deferens.

·         Seminiferous tubules open into vasa efferentia through rete testis.

·         The vasa efferentia leaves the testis and open into epididymis.

·         The epididymis leads to vas deferens that ascends to the abdomen through inguinal canal and loops over the urinary bladder.

·         Vas deferens receives a duct from seminal vesicle and opens into the urethra as the ejaculatory duct.

·         Urethra originates from the urinary bladder and extends through the penis to its external opening calledurethral meatus.

Accessory glands:

·         Includes

o    Paired seminal vesicle

o    A prostate gland

o    Paired bulbourethral gland.

·         Secretion of these glands constitutes the seminal plasma.

·         Seminal plasma rich in fructose, calcium, and certain enzyme.

·         Secretion of bulbo-urethral glands helps in lubrication of penis.

External genitalia:

·         Penis is the external genitalia.

·         It is made of special tissue that helps in erection of the penis to facilitate insemination.

·         The enlarged end of penis is called glans penis.

·         Glans penis is covered by a loose fold of skin called foreskin.

THE FEMALE REPRODUCTIVE SYSTEM

·         Located in the pelvic region of the female.

·         The female reproductive system includes:

o    A pair of ovaries

o    A pair of oviduct.

o    Uterus

o    Cervix

o    Vagina

o    External genitalia.

o    A pair of mammary gland.

Ovaries:

·         It is the primary female sex organs that produce the female gamete (ovum).

·         It also produces several steroid hormones.

·         The ovaries located in the lower abdomen.

·         Each ovary is about 2-4 cm in length.

·         Connected to the pelvic wall and uterus by ligaments.

·         Each ovary is covered by thin epithelium which encloses the ovarian stroma

·         The ovarian stroma has two zones

§  A peripheral cortex.

§  An inner medulla.

Oviduct:

·         Oviducts, uterus and vagina constitute the female accessory ducts.

·         Each fallopian tube is about 10-12 cm long and extends from the periphery of each ovary to the uterus.

·         Close to the ovary the oviduct has a funnel shaped structure called infundibulum.

·         The edges of the infundibulum possess finger-like projections called fimbriae, which helps in collection of the ovum after ovulation.

·         The infundibulum leads to a wider part of the oviduct called ampulla.

·         The last part of the oviduct is called isthmus which joined to uterus.

 

Uterus:

·         It is single and is called womb.

·         It is inverted pear shaped.

·         Attached the pelvic wall by ligaments.

·         The uterus opens into vagina through a narrow cervix.

·         The lumen of cervix is called cervical canal.

·         Cervical canal along with vagina form the birth canal.

·         The wall of the uterus has three layers of tissues

o    Perimetrium: external thin membranous.

o    Myometrium: middle thick layer of smooth muscles

o    Endometrium: inner glandular layer.

·         Endometrium undergoes cyclical changes during menstrual cycle.

·         Myometrium exhibits strong contraction during delivery of the baby.

 

External genitalia:

·         It includes following structure:

o    Mons Pubis: cushion of fatty covered by skin and pubic hair.

o    Labia majora: fleshy folds of tissue which extends down from the mons pubis and surrounds the vaginal opening.

o    Labia minora: are paired folds of tissue under the labia majora.

o    Hymen: the opening of vagina is often covered partially by a membrane called hymen.

o    Clitoris: a tiny finger-like structure lies at the upper junction of two labia minora above the urethral opening.

Mammary glands:

·         Mammary gland consists of glandular tissue and fat.

·         Glandular tissue of each breast divided into 15-20 mammary lobes.

·         Mammary lobes contain cluster of cells called alveoli.

·         The cells of alveoli secrete milk, stored in the lumen of alveoli.

·         The alveoli open into mammary tubules.

·         The tubules of each lobe join to form a mammary duct.

·         Several mammary ducts join to form a wider mammary ampulla.

·         Mammary ampulla connected to lactiferous duct, through which milk is sucked out.

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GAMETOGENESIS

Spermatogenesis is the process of formation of sperm from the germ cell in the testes. Oogenesis is the formation of mature female gamete or ovum. Reproductive cycle of female primates is called menstrual cycle.

PARTURITION AND LACTATION

Delivery of foetus is known as parturition. It is triggers with the release of oxytocin. Production of milk from mammary gland is known as lactation.

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