الفهرس 
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Abstract
The aim of the present study was to investigate the effect of ovarian follicular size, oocyte quality and presence of corpus luteum on in vitro nuclear maturation of buffalo oocytes. Chemical analysis of follicular fluids and their relation to the in vitro maturation of oocytes were also investigated. Buffalo ovaries at various stages of estrous cycle were collected from the slaughterhouse, preserved in saline solution containing antibiotics and immediately transported to the laboratory. Follicular fluid (FF) and Cumulus oocyte complexes (COCs) were aspirated from the ovarian follicles. Oocytes having at least three layers of compact cumulus cells and homogenous cytoplasm were selected for all experiments except that of oocyte quality and matured in a defined basic medium tissue culture medium199 (TCM199) for 21-24 h at 38.5°C under 5%CO2 in air and 95% humidity, and FF was stored at -20 °C. Blood samples were also collected from these buffaloes before slaughtering, and plasma was separated and stored for further analysis. Samples were classified into three groups according to follicle diameter i.e. small (<6 mm), medium (6- 8 mm) and large follicles(>8mm). Samples were classified also into two groups according to ovarian phase (luteal or follicular phase). The FF and plasma samples were analyzed for various biochemical constituents, using commercial kits. Present results indicated that the highest percentage of oocytes reaching metaphase II (MII) stage within 21-24 h of culture were obtained from medium follicles, followed by large and small follicles, which present maturation rates 84.2, 83.3 and 62.7 respectively.
Differences in maturation rate among three groups were significant (p<0.01). Oocytes of good quality and average quality exhibited maturation rates significantly (p<0.001) higher than those of poor quality oocytes, being 87.2, 83.5 and 59.3, respectively. The oocytes which aspirated from the ovaries in luteal phase recorded non significant (p>0.05) lower maturation rate, compared to the oocytes obtained from the ovaries in follicular phase. Chemical analysis of follicular fluid components indicated that a significant correlation was found between each estradiol-17β (r=0.445*), cholesterol (r=0.555**), calcium (r= 0.547**) and oocyte maturation rate respectively. On the other hand, present results indicated a negative significant correlation between each of Aspartate aminotransferace (AST) (r= -0.815***), alkaline phosphatase (r= -0.551**), acid phosphatase (r= -0.812***), potassium (r= -0.582**) and oocyte maturation rate. The present study recorded also a non significant correlation between each of progesterone, triglycerides, testosterone, creatinine, total protein, albumin, globulin, urea, Alanine aminotransferace (ALT), magnesium, phosphorus and sodium and oocyte maturation rate.