The purpose of this study was to investigate biometrical and histological structure of the buffalo ovaries. In this regard the buffalo ovaries were collected at Urmia slaughterhouse. After removing the non - ovarian tissue the specimens were measured for biometrical parameteres and then processed for histological examination. The results of the biometrical studies have shown that the mean length, Width and diameter of adult buffalo ovaries were 2.46 ± 0.07, 1.77 ± 0.07, 1.50 ± 0.04 cm respectively. The ovarian mean weight was 3.72 ± O.?7 g. This parameters in buffalo calves ovaries were 2.25 ± 0.13, 1.37 ± 0.08, 1.10 ± 0.06 cm and 1.53 ± 0.17 g respectively. The histological study revealed that the distribution of the majority of primordial follicles were in close contact to the tunica albuginea, but with the initiation of follicular growth at first, the distance between follicles and surface epithelium increased whereas with continuation of the growth this distance were reduced. ZP formation initiated in primary follicles and continues thicking up to matura follicle. Accumulation of vitelline granules were developed on the stage of follicular growth, and distribution of this granule in oocyte was unequal and mostly accumulated in one pole of occytes. Granulosa thecal layers in healthy follicles were negative for ORO stain, Whereas at least in the granulosa layer of the atretic follicles strongly positive reaction was observed.
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