Abstract
In this experiment, oocytes were collected from goat ovaries available in slaughterhouse by follicle puncture method. Morphologically culturable type of oocytes which having compact, multilayered cumulus granulosa cell complex and evenly granulated cytoplasm, was separated under a stereozoom microscope. Oocytes were washed thoroughly in maturation medium containing TCM-199, 1 µg/ml estradiol-17β, 0.5 µg/ml FSH, 100 µg/ml LH, 3 mg/ml BSA and 10% estrus goat serum. Washed oocytes were cultured into maturation medium on granulosa cell monolayer. Culture plate was then kept into CO2 incubator at 38±1°C, maximum humidity and 5% CO2 for 18 h. After maturation the oocytes were washed thoroughly with maturation medium containing polyvinyl alcohol (PVA) without serum and BSA and further cultured for 12 h for secretory proteins of oocytes. PVA medium was collected, pooled and concentrated by 5000 cut off centrisart. Secretory proteins were separated on 12.5% SDS-PAGE. A total number of 3.41 oocytes per ovary were obtained and 2.17 culturable oocytes per ovary were cultured into maturation medium. After 18 h of maturation, 4,567 oocytes (1.82 oocytes per ovary) were further cultured into serum and BSA free PVA medium for its secretory proteins. Four secretory proteins of oocytes with approximately molecular weight of 45, 55, 65 and 95 kDa were obtained on SDS-PAGE in silver staining and three proteins with approximately molecular weight of 45, 55 and 65 kDa in Coomassie brilliant blue staining. In conclusion, four secretory proteins with approximately molecular weight of 45, 55, 65 and 95 kDa was obtained from in vitro cultured oocytes of goats. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 3 : 340-345)
Highlights
The mammalian oocytes maturation comprises of two steps (a) a period of oocyte growth and (b) a period of final nuclear and cytoplasmic preparation
Granulosa cells attachment was observed after 5-6 h of Washed oocytes were further washed in maturation post-seeding and cell confluence was prominent within 4-5 medium in a sterile petridish
Washed oocytes were put into this well in maturation medium under mineral oil
Summary
The mammalian oocytes maturation comprises of two steps (a) a period of oocyte growth and (b) a period of final nuclear and cytoplasmic preparation. The normal oocyte growth is related to its size and quality that continues with the process of folliculogenesis in first phase. The second phase is related to the process of meiosis. The growth of oocyte is essential for resumption of meiosis within the follicle that was arrested at the dictyate stage. Oocyte is not capable of resuming meiosis without further growth and development in most of the mammalian species. Nuclear as well as cytoplasmic maturation of oocyte is a prerequisite for successful fertilization leading to embryo development. The oocyte and follicle undergo concurrent growth (Carnoll et al, 1991)
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