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MENSTRUAL CYCLE

MENSTRUAL CYCLE 
 
Characteristics

  1. menarche at age 11-14
  2. entire cycle 28 +/- 7 days, with bleeding for 1 - 6 days 
  3. polymenorrheaif < 21 days 
  4. oligomenorrheaif > 35 days 
  5. 25-60 mL of blood loss per cycle


  1. Day 1 to days 3-7: Menstruation, FSH and LH levels are rising.
  2. Rising FSH stimulates growth of several ovarian follicles and maturation of an ovum.
  3. FSH and rising LH stimulate the follicles to produce estrogen.
  4. Estrogen causes proliferation of endometrium and further stimulates ripening of the ovum.
  5. Estrogen triggers a LH surge which is responsible for ovulation.
  6. After ovulation, progesterone produced by the corpus luteum stimulates secretory changes in the endometrium.
  7. Deterioration of the corpus luteum causes progesterone to decrease.
  8. Decreasing progesterone and estrogen stimulate pituitary to produce FSH and LH.

Proliferative/Follicular Phase

  1. first day of menses to ovulation 
  2. variable in length
  3. low basal body temperature
  4. estrogenic
  5. endometrial priming
  6. ovarian follicular development

Ovulatory Phase

  1. LH surge leads to ovulation (14 days before the onset of menses
  2. temperature rise (0.5 C – 1 C )
  3. increased cervical, acellular mucous with spinnbarkeit (long stretchy threads) and ferning with KOH, seen under the microscope
Secretory/Luteal Phase

  1. ovulation to onset of menses 
  2. fixed in length: 14 days
  3. corpus luteum formation
  4. progesterone and estrogen secreted from corpus luteum
  5. progesterone prepares endometrium for embryo implantation
  6. without pregnancy ----> progesterone withdrawal ---> constriction of spiral arteries ----> ischemia and endometrial necrosis ----> menses
  7. while lining is being shed, surface epithelium is already beginning
    to regenerate

MENSTRUAL CYCLE MENSTRUAL CYCLE Reviewed by Radiology Madeeasy on August 22, 2010 Rating: 5
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