Biochemical constituents of ovarian follicular fluid in ruminants and their significance in follicle and oocyte development

Abstract

The developmental potential of oocyte largely depends on the follicular fluid ionic, metabolite and hormonal composition. The antrum cavity is filled with follicular fluid that bathes the cumulus– oocyte complexes and it is a source for nutrients and also in the physiological, biochemical and metabolic aspects of the nuclear and cytoplasmic maturation of the oocyte and the process of ovulation. The mechanisms behind follicular fluid accumulation as of yet have not been fully elucidated, however it is hypothesized that follicular fluid is derived from the blood. Follicular fluid is an indicator of the secretory activities and metabolism of follicular cells and thus could be related to the follicular quality. Though there is a species difference in follicular fluid composition, the trends shows that as follicles became larger, the concentrations of glucose, cholesterol, calcium, phosphorus and sodium increased while those of total protein, urea, triglycerides, chloride, potassium and magnesium, alkaline phosphatase and lactate dehydrogenase significantly decreased. Apart from various classical hormones (FSF, LH, estradiol, progesterone, thyroid hormones) many growth factors and local factors are present in follicular fluid. The present paper overviewed the biochemical composition (ionic, metabolic and hormonal) of the follicular fluid in ruminants (cattle, buffalo, sheep and goats) and discussed their on oocyte development and maintenance of fertility in the female animal.