New concepts on fooliculogenesis in mamamals

New concepts on fooliculogenesis in mamamals

NEW CONCEPTS ONFOOLICULOGENESIS IN MAMAMALS

by G.M WANI PhD,DVM (Germany)

Follicular development and Mensturation.

At mensturation the follicular atresia is already completed. All developing follicles die down, only one pre-ovulatory follicle remains. The process of apoptosis ,kills all other follicles with their oocyte within.The causes of atresia are unknown, but FSH helps to prevent it.Antral follicle development in cattle has ben onserved in cows as early as at e weeks of age(Evans et al,1994)The preantral follicle development is thought to be indepent of response to gonadotrphin.It is only the early antral follicle which responds to the gonadotropins.The role of hypothalamic and pituitary hormone do play a significant role at puberty.The recruitment of primodial follicle from the resting pool is continous in women through out her life time,thus the menopause or even the manusturation has seemingly little effect on these processes.(Baird,1987,Adashi 1994,Santbrink et al,1995,McGee and Hsueh,2000)The development of follicles beyond 2-5 mm diameter occurs continuously in the late luteal phase(Gougeon,1979)

Biochemicalfactors offollicle maturation.

The biochemical and mechanical environment enable the development of controllable systems to investigate the fundamental biological principles underlying follicle maturation as described (West,Shea and Woodruff,2010) Some of the facts revealed are as. FSH, in the presence of low levels of LH at the start of the follicular phase, has a mitotic action on estrogen-producing granulosa cells.This encourages differentiation and activates the synthesis of the genetically-determined products like somatomedin, inhibin , activin.and of the LH receptor. The higher LH levels, during the second half of the follicular phase restricts proliferation of granulosa cells.The low levels of LH, synergistically with insulin-like growth factor 1, bring about an increase in estrogen synthesis from aromatisable androgens. The FSH, LH thus facilitates the production of cybernins,essential growth factors, and preovulatory progesterone surge. Abnormalities of endocrine, paracrine or autocrine regulation of follicular maturation may lead to atresia. Future rational uses of human FSH and LH are obvious and involve the optimisation of ovulation induction and

ovarian follicular growth regulators new reseach

Role of IGFs

August 4, 2010 -- Researchers supported by the National Institutes of Health have for the first time activated mouse egg cells at the earliest stage of their development and brought them to maturity. In a related experiment, the researchers replicated the finding by also bringing human eggs to maturity in the laboratory. This was possible by understanding the potential role of IGFs in follicular growth .The expression of mRNAs encoding IGFI,IGF2,IGFIR,IGF-binding protein 2(IGFBP2),IGFBP4 AND IGFRP4 and IGFBP5.The in situ hybridization was used to unveil these facts.

Maturation of early egg cells

Imature eggs need to be matured before in-viro fertilization.Imature egg cells are matured under in vitro conditions in the laboratory.These techniques although perfected and used for few decades use the late stages of oocytes.The earlystages are not receptive.New regulation mechnism in mice may be replicated and tested in higher mammals and now human early follicle shall be cultured ad matured in laboratory factors discussed in our earlier paper .

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