Ovarian cycle (Menstrual cycle)
- It is a series of cyclic changes occurring in the reproductive tract of female with the periodicity of 28 days
- It is also known as menstrual cycle,
- also known as endometrial cycle
- It occur From puberty to menopause
- It is characterized by loss of vaginal blood (breaking of endometrium wall of uterus)
- The cycle is under Influenced of hormones secreted by pituitary gland (FSH and LH), and ovary (progesterone and oesterogen).
Complete in 3 phase
- Menstrual phase
- Proliferative phase or follicular or ovulatory phase
- Luteal or secretory phase
Figure: Menstrual cycle
- This phase is characterized by discharge of blood, connective tissues and mucus due to cast off of epithelial lining of endometrium wall
- It Lasts for 3-5 days
- Ovum remain unfertilized,
- At this time level of oestrogen and progesterone is very low in blood resulting in Breaking of endometrium wall of uterus
- About 50-100 ml blood with mucus are discharges as menstrual flow.
- This phase is characterized by rapid proliferation and repair of damaged endometrium wall
- It Lasts for 9-10 days (5th – 14thdays)
- Anterior pituitary gland release Follicular stimulating Hormone (FSH) which stimulates development and maturation of grafian follicle. So, it is also known as Follicular Phase.
- Mature grafian follicle secrete oestrogen. Its level gradually increases and maximize at 12thday
- Oestrogen stimulate endometrium repair and proliferation. It also stimulate Ovulation
- Endometrium become 2-3 mm thick and highly vascular
- This phase is characterized by release of Ovum from mature graffian follicle which is stimulated by the secretion of luteinizing hormone (LH) by pituitary gland.
- It Lasts for 12-14 days (14th-28th day)
- LH along with FSH stimulate ovulation.
- Mature graffian follicle release ovum and the rapture follicular cell form corpus luteum
- Corpus luteum secrete progesterone, high level of progesterone inhibit maturation of any other follicles
- Progesterone also stimulate thickening of endometrium wall
- When ovum remain unfertilized, corpus luteum degenerate; level of both hormone (progesterone and oestrogen) decreases, causing breaking of endometrium wall continuing the menstrual phase.