Basim Abu-Rafea, MD, FRCSC, FACOG Assistant Professor & Consultant Obstetrics & Gynecology Reproductive Endocrinology & Infertility Advanced Minimally Invasive Gynecologic Surgery Department of Obstetrics & Gynecology King Khalid University Hospital King Saud University

Divide the cycle into three phases: 1.Follicular phase 2.Ovulation phase 3.Luteal phase.

 This process occurs over 10–14 days of time.  Features a series of sequential actions of hormones and autocrine - paracrine peptides on the follicle.  Follicle destined to ovulate.

 By 16–20 weeks gestation 6–7 million.  1–2 million at birth.  300,000 to 500,000 at puberty.  400 to 500 follicles will ovulate during a woman's reproductive years.

 Initial follicular development occurs independently of hormone influence.  FSH stimulation rescues a cohort of follicles from apoptosis, propelling them to the preantral stage.  FSH-induced aromatization of androgen in the granulosa results in the production of estrogen.  FSH and estrogen increase the FSH receptor content of the follicle and stimulate the proliferation of granulosa cells.

Selection process is a result of two estrogen actions: 1.A local interaction between estrogen and FSH within the follicle. 2.The effect of estrogen on pituitary secretion of FSH.

Activin

 FSH ACTIONS  Recruitment & Rescue  Stimulates aromatization of androgens to estrogens  Increases granulosa cell content of FSH and LH receptors  stimulates proliferation of granulosa cells  ESTROGEN  Suppressive influence on FSH  Positive feedback influence on LH secretion  Induces LH & FSH receptors

 The primordial follicle is nongrowing.  Consists of an oocyte, arrested in the diplotene stage of meiotic prophase.  Surrounded by a single layer of spindle-shaped granulosa cells.

 The mechanism for determining which follicles and how many will start growing on any given day is unknown.  Growth and atresia (apoptosis) are not interrupted by pregnancy, ovulation, or anovulation.  This process continues at all ages, including infancy and around the menopause.

 Development of follicles occurs over the time span of several menstrual cycles.  It takes approximately 85 days to achieve preovulatory status.  (Rescued) by follicle-stimulating hormone (FSH)

 The LH surge initiates:  The continuation of meiosis in the oocyte  Luteinization of the granulosa  Synthesis of progesterone and prostaglandins within the follicle  Progesterone:  Enhances the activity of proteolytic enzymes  Essential to induce the midcycle FSH peak

Mechanism of follicular rupture:   Follicular pressure  The dominant follicle protrudes from the ovarian cortex  Enzymatic rupture of the follicular wall  Gentle release of the oocyte surrounded by the cumulus granulosa cells

 Lasts 14 days  FORMATION OF THE CORPUS LUTEUM  After ovulation the point of rupture in the follicular wall seals  Vascular capillaries cross the basement membrane & grow into the granulosa cells  availability of LDL - cholestrole

 Marked  in progesterone secretion  Progesterone actions:  Suppress follicular maturation on the ipsilateral ovary  Thermogenic activity  Endometrial maturation  Progesterone peak 8 days after ovulation  Corpus luteum is sustained by LH  hCG rescues the corpus luteum

 The demise of the corpus luteum results in a nadir in the circulating levels of estradiol, progesterone, and inhibin.  The decrease in inhibin-A removes a suppressing influence on FSH secretion in the pituitary.  The increase in FSH is instrumental in rescuing an approximately 70-day-old group of ready follicles from atresia

 Mean length of the menstrual cycle is 28 days (21-35).  Average duration of menses is 3 to 7 days.  The normal estimated blood loss is 30 ml.

 Basal layer:  Adjacent to the myometrium  Unresponsive to hormonal stimulation  Remains intact throughout the menstrual cycle  Functional layer:  Zona compacta  superficial  Spongiosum layer

 Follicular /proliferative phase  Estrogen  mitotic activity in the glands & stroma    endometrial thickness from 2 to 8 mm  Luteal /secretory phase  Progestrone   Mitotic activity is severely restricted  Endometrial glands produce then secrete glycogen rich vacules  Stromal edema  Stromal cells enlargement  Spiral arterioles develop, lengthen & coil

 Hormone withdrawal leads to a modest shrinking of the tissue height of the endometrium.  Flow in the spiral vessels diminishes, venous drainage is decreased.  These reactions lead to endometrial ischemia and stasis.  The prostaglandin content (PGFα and PGE 2 ) reaches its highest levels at menstruation.  The endometrium is infiltrated with leucocytes.

 The menstrual fluid is composed of:  The autolysed functionalis  Inflammatory exudate  Red blood cells  Proteolytic enzymes