Veterinary Physiology-III

PROGESTERONE

Source

• Luteal cells of corpus luteum
• Also produced from adrenal cortex and placenta.

Functions

• Prepares the endometrium for implantation and maintenance of pregnancy by increasing the activity of the secretary glands in the endometrium and by inhibiting the motility of the myometrium. In CL-dependent animals (cow, goat and sow) CL-verum maintains the secretions of progesterone throughout gestation period, while in placental dependent animals (mare and ewes) placenta acts as an additional source of P4 secretion to maintain pregnancy by inhibiting the myometrial activity of oestrogen on uterus
• Acts synergistically with estrogen to induce behavioural signs of estrus
• By negative feedback mechanism. Progesterone inhibits FSH output and pulsatile LH release from the anterior pituitary. Thus prevents follicular maturation during luteal phase of the estrus cycle in the cycling animals. During pregnancy progesterone exhibits negative feedback inhibition on FSH release and LH surge to prevent ovulation.
• Responsible for lobular and alveolar growth in the mammary gland