18 - Physiology of reproduction- Female reproductive system. Ovogenesis. Female sex hormones (estradiol and progesterone), types, physiologic effect, control of secretion. Regulation of menstrual cycle. Pregnancy and lactation. Tests for early pregnancy.

section

why is female reproductive system needed

ovogenesis

oogenesis

femal sex hormones

menstrual cycle

pregnancy

lactation

test for early preganancy

why is female reproductive system needed

The female reproductive system is needed for production of female egg cells necessary for reproduction along with the male gametes. Secondary oocyte is needed.

ovogenesis

formation and maturation of the egg cell

process where primary egg cell becomes a mature ovum Oogenesis

oogenesis

• Oogenesis starts with the transformation of primordial follicles →primary oocytes

• Oocytogenesis is complete either before or shortly after birth in humans, and thus during the menstrual cycle primary oocytes complete maturation through further meiotic divisions.

• The first meiotic division is coordinated by hormones: FSH, estrogen, LH and progesterone.

• The oocyte is stopped in cell division prior to the second meiotic division, which only occurs after fertilization.

femal sex hormone

• LH: produced by the anterior pituitary – stimulates secretion of progesterone and oestrogen

  • release is controlled by Gonadotropin-releasing hormone (GnRH) from hypothalamus.

  • responsible for the release of (FSH) and (LH) from the anterior pituitary gland.

• Follicle stimulating hormone :

  • secreted by anterior pituitary stimulates the growth of ovarian follicles

  • FSH→follicle→ estrogens

• Progesterone is a hormone produced by the ovaries in response to the release of LH and FSH from the pituitary gland.

  • Progesterone is involved in preparing the uterus for implantation

  • increasing the amount of cervix mucus

  • decreasing the maternal immune response.

  • Progesterone has a negative feedback on LH and FSH during luteal phase

• Estrogen

  • helps in production of eggs, involved in metabolic functions e.g. bone formation, salt and water retention and increased cortisol levels, breast development, female sex characteristics

mesntrual cycle

Def: cycle in which approx every 28 days,

Menstrual Cycle (Overview of Follicular Phase to Ovulation):

• Menstruation: The uterus sheds its lining (blood and tissue).

• Follicular Phase: A new follicle starts developing in the ovary.

• The follicle produces estrogen, which thickens the uterine lining.

• Rising estrogen also triggers a rise in LH.

• LH surge around day 14 causes the egg to complete meiosis I and be released — this is ovulation.

After Ovulation:

• The leftover follicle becomes the corpus luteum.

• Stimulated by LH, it produces progesterone and some estrogen.

• Progesterone maintains the uterine lining.

• High hormone levels cause LH and FSH to drop.

preganancy

High levels of estrogen and progesterogen, hcg- by placenta- prevents regression of corpus luteum

lactation

Lactation is the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her child.

• Lactation is under endocrine control, with several hormones stimulating reponses including progesterone, estrogen, prolactin, and oxytocin.

• Lactogenesis- is the process of changes to the mammary glands to begin producing milk, begins during the late stages of pregnancy.

• The delivery of the placenta, and the decreasing of progesterone, estrogen, and HPL- human placental lactogen levels, stimulates milk production.

• Lactation maintained by suckling

• Colostrum is the first milk a breastfed baby receives. It contains higher amounts of WBCs and antibodies than mature milk.

test for early preganancy

1. Rosette inhibition: a test for the detection of EPF- early pregnancy factor which is an immunosuppressive substance. It can be detected within the blood within 48 hrs of fertilization

2. Obstetric ultrasonography- done as early as 4.5 weeks the embryo can be seen and measured at 5.5 weeks

3. Human chorionic gonadotropin -hCG can be detected in urine or blood after implantation (6-12 days after fertilization). Urine test strips have detection thresholds of 20 - 100 mIU/mL, depending on the brand.