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Endocrine System

Hormones are chemical substances secreted in the tissue called ductless glands and are transferred to another point called target organ where they exert their effects.

The male reproductive hormones

Testosterone or androgen

(i) It brings about the development of male secondary sexual characters and sex drive.
(ii) Essential for the secretion of spermatozoa.
(iii) Maintenance of optimum conditions for sperm formation.
(iv) It promotes growth of accessory glands.

The female reproductive hormones

(a) Oestrogen (secreted by the graffian follicle)

(i) It brings about the development of the female secondary characteristics.
(ii) It helps in the secretion of ovules ( ova).
(iii) Brings about heat, and menstrual cycle.
(iv) It helps in the development of the mammary gland.
(v) It stimulates the growth of the duct system in the mammary gland.

(b) Progesterone

(i)  It takes care of implantation of the embryo in the uterus.
(ii) It inhibits oestrus and ovulation.
(iii) Helps in maintaining pregnancy.
(iv) It sets the uterus for implantation.
(v) It helps in the continuation of pregnancy.

(c) Relaxin

(i) Help in the relaxation of the pelvic ligament and helps to draw the pubic bones during parturition.
(ii) It allows for free and flexible passage of the foetus during parturition.

(d) Oxytocin

(i) Helps in the contraction of the female uterine muscle during parturition.
(ii) Encourages milk-let-down.
(iii) Also encourages labour and parturition.
(iv) Helps in the transportation of sperm in the female genital tract.

(e) Prolactin

(i)   It is concerned with lactation.
(ii) It prolongs the period of breast feeding of the young.