The Menstrual Cycle Flashcards
What is the endometrium of the uterus?
The inner lining of the uterus that is shed every month during the menstrual cycyle
-Glandular tissue, under endoncrine control
- Extensive stroma
- Highly vasculurised networked supploed by spiral arteries
- Distinct histological changes with phases of the m cycle (Noyes criteria)
- Columnar epithelial cell lining (proliferates and degenerates in one cycle)
- Glands extend deep into the endometrial stroma
- Implantation occurs 6-12 days after fertilisation
- Window of implantation - endometrium optimally receptive to blastocyst (36hrs).
What comprises the Upper Female Reproductive Tract (FRT)
- The fallopian tubes
- ovarian ligament
- Fimbriae
- UTERUS
- Ovary (perimetrium, myometrium and endometrium)
What is the Lower FRT comprised of?
The cervix and vagina
What is the female repoductive lifecycle?
- Menarche:
- first ovarian-controlled uterine bleed
- Maturation of HPO axis
- increase in oestrogen (Sexual characteristics)
- Childbearing years (mestrual cycle)
- Around 28 day cycle
- menses, menstruatuion (bleeding phase)
- Menopause/Climacteric
- Oestrogen withdrawl, follicle depletion
- Cessation of menses
- Size, function of ovaries
- Mean age 51.4
What is the differnece between the ovarian and uterine cycle?
- Ovarian : interval between successive ovulations
- describes ovum maturation and release under endocrine regulation
- Progression of follicle - corpus luteum
- Uterine cycle:
- comprises the follicular pase (1-14 days) and the luteal phase (15-28 days)
- Folliculogenesis
- Uterine cycle - describes the effects of oestrogen and progesterone on the uterus (endometrium)
- Has a proliferative and secretory phase
- Has vascular funcrtion, menses
- Angiogenesis
What are the main reproductive hormones in the FRT?
Oestradiol-17ß
* produced from androstenedione and aromatase in granulosa, CL and adipose
**Progesterone (P4) **
* secreted by corpus luteum
**Follicle Stimulating Hormone (FSH) **
* follicle development and recruitment
**Luteinising Hormone (LH) **
* maturation of dominant follicle, ovulation, maintenance of the CL
**Inhibins **
* produced by ovarian granulosa cells to inhibit FSH secretion; Inhibin A during luteal
phase; Inhibin B in follicular phase
Anti-Mullerian Hormone (AMH)
* marker of ovarian reserve
What is the action of oestrogen (c18 steroid)?
- Widespread effects on reproductive, musculoskeleta,vascular and cns
- Regulate GnRH secretion
- stimulate proliferation of endometrium
- Prepares endomentrium for progesterone action
- -Stimulate sex characteristics of female
- Stimulates ductal growth of breast tissue.
What is the action of Progesterone (c21 steroid)?
- Pro gestation - hormone of pregnancy
- Regulate GnRH secretion
- Prepare endometrium for implantation
- Stimulate decidualisation of the endometrium
- Maintain the uterus during pregnancy
- Stimulate growth (alveolar) of breast tissue
- Synergistic and opposing effects to oestrogen
What is the idealised menstrual cycle?
- Day 1-7 bleeding
- Proliferative (Follicular) - when bleeding is more or less over - endometrium begins to regenerate
- Day 12-14 Ovulation
- Secretory (Luteal) phase (!4-28)
- Implantation- this cycle stops if pregnancy occurs
What is dysmenorrhoea?
- painful periods
What are the proliferative and secretory phase dominated by?
Proliferative - oestrogen - dominated
- variable duration typically 14 days
Secretory - progesterone dominated
Important so that women know when they are most fertile
Why do FSH and LH begin to increase at the start of the menstrual cycle?
- act on the follicles of the ovary which secrete eostrogen
- these promote endometrial proliferation
- Around Day 14 - there is a LH peak which is needed for oestrogen levels to rise prior to ovulation = positive feedback regulation
- After ovulation LH levels decrease rapidly
- Progesterone levels increase so that endometrium can thicken so that a blastocyst can embed (prepares endometrium for implantation)
- If no implantation, progesterone levels, and oestrogen levels fall off and LH and FSH levels begin to rise again
What process do inhibins inhibit in the menstrual cycle?
- The recruitment of follicles
- Once there are enough follicles the growth of other follicles are supressed
stalks
What are pinopodes?
- Markers of endometrial receptivity that grow on the endometrial cell layer
- Attract the blastocyst to them
What is the difference between proliferative and secretory ohase endometrium?
- Prolferative : round,regular. Stroma- supprt,nutrients
- Secretory - tortuous,twisted glands .Glycogen droplets prepares for conception - first nutrition for embryo