Question

How do FSH, LH, estradiol and androgens interact with one another to produce accelerated follicular growth in the final stage of follicular development?

Your answer should reference the synthesis of steroid hormone levels as well as changes in the numbers of thecal and granulosa cells.

Answer 1

• The follicular phase and luteinizing hormone () start with the maturation of the follicles in the ovary and ends with ovulation.
• Follicle-stimulating hormone ( FSH ) and luteinizing hormone ( LH ) is secreted by the anterior-pituitary gland.
• A rise in the FSH levels recruits 5 - 7 tertiary follicles to enter into the menstrual cycle.
• FSH induces the proliferation of the granulosa cell of the in developing follicle.
• It also causes the expression of luteinizing hormone receptors on the granulosa cells.
• The ovum inside the dominant follicle also develops
• The maturing follicles begin to produce estrogen and progesterone
• The follicle that produces a high level of estrogen predominates.
• This high level of estrogen reduces the level of FSH and LH.
• This causes atresia of the other follicles.
• All this together constitutes the accelerated growth of the follicle into the large follicle ( vesicular follicle graafin)
• High level of estrogen promotes the formation of endometrium in the uterus
• Crypts in the cervix promote the formation of fertile cervical mucus ( reduced mucus acidity)
• Ovulation occurs 30 hrs after the LH surge.
• Graafin follicle -
  • consists of central atrum
  • 6 different cells -
    • Theca Externa - smooth muscle cells with autonomic innervation
    • Theca Interna - they are differentiated thecal interstitial cells. They are highly vascularized. This allows hormones, vitamins, nutrients to reach them
    • Basal lamina -
    • granulosa -
      • outermost - membrana granulosa
      • Innermost - Periantral
      • Intermediate - cumulus oophorus
      • Juxtaposed to the oocyte - corona radiata