Cumulus oocytes complexes (COCs) were collected by aspiration from antral follicles (2 to 8 mm diameter) with 18 gauge needle. Good quality COCs based on their morphological appearance (covered by at least four layers of compacted cumulus cells and evenly granulated ooplasm), were washed twice in Tissue Culture Medium -199 (TCM-199) supplemented with 2% foetal bovine serum (FBS), 0.3 mg/mL glutamine and 50 μg/mL gentamycin and. Oocytes collected in cold and warm seasons were cultured for 24 h and based on cumulus expansion they were divided into two groups. One group were subjected to IVF (Faheem et al., 2011) and in the other group, oocytes were denuded by vortexing and fixated in 3:1 (Methonal:glacial acetic acid) solution for 24 h at room temperature by air tighten up the petri dish with parafilm. After fixation each denuded oocytes were dyed with 1% Orcein and their meiosis stages were recorded. Apart from this, oocytes collected in cold seasons were also submitted to heat stress, being maturated at 39.5°C (HS1) and 40.5°C (HS2) for 24 h. Oocytes maturated in heat stress were subjected to dying and IVF as mentioned above.