Estimativa da população, caracterização morfométrica e ultraestrutural e criopreservação de folículos ovarianos pré-antrais de gatas domésticas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The aim of the present study was to estimate the population and morphometrically and ultrastructurally characterize preantral follicles from queen ovaries. In the first experiment, a total of 190 preantral follicles (100 primordial, 60 primary and 30 secondary) were analyzed by light microscopy. The diameters of the follicle, oocyte and oocyte nucleus were taken and the number of granulosa cells was counted using a computer program. Queen ovaries presented 37,853 6,118 preantral follicles on average, with 87% primordial, 10.4% primary and 2.3% secondary follicles. Significant differences were observed in the 3 follicular classes in regard to follicular, oocyte and oocyte nucleus diameters and granulosa cell number (p<0.05). In regard to ultrastructure, queen preantral follicles presented many unique characteristics, such as early zona pellucida formation in primary follicles and the organization of mitochondria and other organelles in conglomerates and cortical granules aligned at the peripheral zone in secondary follicle oocytes. In the second experiment, Ovaries from 5 queens were collected, sectioned, and cryopreserved by vitrification or slow cooling. Histological analysis of follicle integrity showed that the percentages of normal follicles in ovarian fragments in the vitrified (15.75.7) and slow cooled (60.69.5) groups were different to those of controls (89.14.8) (fresh ovarian fragments). The percentages of normal follicles in the slow freezing group significantly differ from that observed in the vitrification group. Follicular degeneration occurred more in the vitrification group than in the other groups. For ultrastructural analyses, the cryopreserved group demonstrated some cryoinjuries in the oocytes. For slow cooling or vitrified groups, the most common alterations were within the oocytes cytoplasm which was disorganized, with mitochondria demonstrating a more clear aspect, and a greater number of vesicles. Few endoplasmatic reticulum cisternae were observed within the ooplasm. In some oocytes the cytoplasm and the granulosa cells were detached leaving an empty space between them. In conclusion, this study described the morphometry and ultrastructure of queen preantral follicles and the preantral follicle population in the ovaries, establishing a pattern for the species and consequently allowing comparisons with other species. For cryopreservation it can be conclude that both methods bring cryoinjuries to the oocyte, especially vitrification.

ASSUNTO(S)

feline electron microscopy morphology outros felinos oocyte morfologia microscopia eletrônica ovócito

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