Localization and expression of proliferating cell nuclear antigen (PCNA)

Abstract

The present study was designed to determine the expression of proliferating cell nuclear antigen protein (PCNA) and cyclin B1 in buffalo during ovarian follicular development. PCNA and cyclin B1 were localized immunohistochemically in paraffin embedded ovarian sections whereas the expression of mRNA was done through semi-quantitative RT-PCR. Immunohistochemical studies demonstrated presence of PCNA and Cyclin B1 immunoreactivity throughout the follicular development. Positive immunoreactions of PCNA in preantral and actively growing small to large antral follicles showed extensive labeling in the layer of granulosa and theca cells. In contrast, cyclin B1 immunoreactivity was localized to the granulosa cells and it increased from small, medium to large follicles. mRNA transcript of PCNA (496 bp) and cyclin B1 (293 bp) was detected in ovarian stromal tissue, granulosa cells, preantral and antral follicles respectively. Follicles demonstrating advanced atresia showed only limited or no PCNA and cyclin B1 labeled granulosa and theca cells. In conclusion, follicular growth and development in buffalo ovary may be effectively monitored by determining the expression of PCNA and Cyclin B1 in granulosa cells.