Describe the sites of production of oestrogen and progesterone in the menstrual cycle and in pregnancy

SouravNovember 15, 2024

Answer

During the menstrual cycle and pregnancy, oestrogen and progesterone are produced at different sites and play crucial roles in regulating reproductive functions. Here’s a detailed description of their production sites and functions:

Oestrogen

1. Menstrual Cycle:
   • Production Site: Oestrogen is primarily produced in the ovaries, specifically by the developing follicles and the corpus luteum. The dominant follicle secretes estradiol, the most potent form of oestrogen, during the follicular phase, particularly just before ovulation.
   • Function: Oestrogen is responsible for:
     • Stimulating the growth and thickening of the endometrial lining in preparation for a potential pregnancy.
     • Regulating the menstrual cycle by providing feedback to the pituitary gland to control levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
     • Inducing changes in cervical mucus to facilitate sperm entry.
2. Pregnancy:
   • Production Site: During pregnancy, the placenta becomes the primary source of oestrogen production, particularly estriol, which is produced in larger quantities than during the menstrual cycle.
   • Function: Oestrogen during pregnancy helps:
     • Maintain uterine lining and promote its growth to support the developing fetus.
     • Stimulate breast tissue development in preparation for lactation.

Progesterone

1. Menstrual Cycle:
   • Production Site: Progesterone is produced by the corpus luteum after ovulation. This structure forms from the remnants of the follicle that released an egg.
   • Function: Progesterone plays several roles during the menstrual cycle:
     • It prepares the endometrium for implantation by making it more receptive and rich in blood vessels.
     • It inhibits uterine contractions to prevent premature shedding of the endometrial lining.
     • If fertilization does not occur, progesterone levels drop, leading to menstruation as the endometrial lining sheds.
2. Pregnancy:
   • Production Site: Initially, progesterone is produced by the corpus luteum until about 8-12 weeks into pregnancy. After this period, the placenta takes over progesterone production.
   • Function: During pregnancy, progesterone is crucial for:
     • Maintaining the uterine environment to support embryo implantation and growth.
     • Preventing further ovulation during pregnancy by inhibiting FSH and LH secretion.
     • Supporting breast tissue development for lactation and preventing uterine contractions that could lead to premature labor.