Menstrual cycle (28 days)आर्तव चक्र (28 दिन)
NCERT Fig 2.9 (schematic) · Class 12 Biology · Chapter 2 · interactive diagram
Parts and their functions
- Menstrual phase (days 1–3/5) (रजस्राव प्रावस्था) — Breakdown of the endometrium and its blood vessels → menstrual flow. It occurs only if the released ovum is not fertilised. Lack of menstruation can mean pregnancy (or stress, poor health, etc.).
- Follicular (proliferative) phase (पुटकीय (प्रचुरोद्भवन) प्रावस्था) — Primary follicles grow into a mature Graafian follicle; the endometrium regenerates by proliferation. Rising FSH and LH stimulate follicle growth and estrogen secretion.
- Ovulatory phase (~day 14) (अंडोत्सर्ग प्रावस्था) — LH and FSH peak in the middle of the cycle; the LH surge causes the Graafian follicle to rupture and release the ovum — ovulation.
- Luteal (secretory) phase (पीत (स्रावी) प्रावस्था) — Corpus luteum secretes large amounts of progesterone, essential to maintain the endometrium for implantation. Without fertilisation the corpus luteum degenerates → menstruation; in pregnancy all these events stop.
- LH (luteinising hormone) (LH (ल्यूटिनाइज़िंग हार्मोन)) — Pituitary hormone; its mid-cycle surge (LH surge) induces ovulation.
- FSH (FSH) — Pituitary hormone; stimulates follicle growth in the follicular phase.
- Estrogen (एस्ट्रोजन) — Made by the growing follicles; rises in the follicular phase and helps rebuild the endometrium.
- Progesterone (प्रोजेस्टेरॉन) — Made by the corpus luteum in the luteal phase; maintains the endometrium.
- Growing follicle (विकासशील पुटक) — Primary → Graafian follicle during the follicular phase.
- Ovulation (अंडोत्सर्ग) — Release of the ovum (secondary oocyte) from the Graafian follicle, about day 14.
- Corpus luteum (पीत पिंड) — Forms from the ruptured follicle; secretes progesterone; degenerates if there is no fertilisation.
- Endometrium (गर्भाशय अंतःस्तर) — Uterine lining: breaks down in menses, proliferates in the follicular phase, is maintained (secretory) in the luteal phase.
- Menstrual flow (रजस्राव) — Lasts about 3–5 days.
Original diagram drawn by Simple Learning Hub, based on NCERT Fig 2.9 (schematic). Report a mistake