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Hellenic Archives of Pathology, Volume 19, Issues 1-3, 2005
Study of the kinetics of germ and granulosa cells
during ovary development in the rat
Balla M., Angelopoulou R., Lavranos G., Kittas C.
Laboratory of Histology and Embryology, Medical School, Athens University
Aim: Study of the kinetics of germ and granulosa cells in the developing ovary of Wistar rats during fetal and neonatal life. Evaluation of the nuclear antigens Ki67 and PCNA as markers of mitotic activity in the gonad and correlation of the findings with others taken from other studies of cell proliferation (mitotic index, BrdU labeling).
Material and Methods: Immunohistochemical detection of PCNA and Ki-67 proteins was performed using PC10 (Dako) and NCL-Ki-67 (Novocastra) antibodies in embryos and neonates. Estimation of reactive/total cell ratio, per cell type (germ and granulosa cells) and visual field was achieved using the Image Pro Plus Software.
Results: Before birth, using the PCNA antibody, the percentage of labeled/ total germ cells (Labeling Index, LI) increases from 71.19 at 14.5 days post coitum (dpc) to 75.66 at 18.5 dpc. It then decreases to 28.57% at birth (22.5 dpc). Immediately after birth, the percentage of labeled/total germ cells increases, reaching 43.58% at 1 day post partum (dpp). Thereafter a further decrease in the percentage of reactive cells is observed resulting to a significant drop of the LI at 7 dpp (18.41%). Using the Ki-67 antibody, the percentage of labeled/total germ cells is generally lower although the fluctuation is similar with that observed using the first marker of cell proliferation. Using the PCNA antibody, the LI of granulosa cells in the developing ovary, increases from 0.70 (at 14.5 dpc) to 28.94 (at 18.5 dpc) and then drops to 18.03 (at 20.5 dpc). At birth, the percentage of reactive granulosa cells, reaches 27.66% and remains high thereafter, reaching a peak value of 49.22% at 7 dpp. Using the Ki-67 antibody, the percentage of labeled/total granulosa cells is generally lower although the fluctuation is similar with that observed using the first antibody.
Discussion: Using the PCNA antibody, the peak value of reactive/total germ cells is observed at 18.5 dpc and the percentage drops thereafter, reaching a minimum level at 7 dpp. Accordingly, using the Ki-67 antibody, the LI is maximum at 14.5 dpc and minimum at 7 dpp. Between 18.5 and 20.5 dpc, the proliferation rate remains high. On the other hand, granulosa cell reaction ratio to both antibodies (PCNA and Ki-67) increases continuously throughout the examined period of time with a maximum value at 7 dpp.
Key words: Ovary, gonadal development, morphogenesis, cell proliferation, mitotic index, granulosa cells.
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