Determination of frequency distribution of oocytes at different maturity phases in the ovaries of roach, Rutilus rutilus [L.]

Background. The frequency distribution of oocytes at different maturity phases can be used to assess environmental effects on gametogenesis in teleosts. As oocyte counting is labour-intensive, little attention is generally paid to changes in oocyte numbers in oogenesis analysis. Materials and Methods. Anterior, middle, and posterior ovarian segments from three pre-spawning female roach, Rutilus rutilus (L.) were fixed in buffered formalin, dehydrated, and embedded in paraffin. Serial 10-µm sections were cut with a microtome and stained with haematoxylin and eosin. This paper compares two methods for determining the frequency distribution of oocytes at different maturity phases and their occurrence in particular segments of the ovaries in roach, Rutilus rutilus: counting oocytes in serial microtome sections and the use of Abercrombie′s formula. Results. Differences between frequency distributions determined by the two methods were statistically insignificant (P > 0.05), as were the frequency distributions of oocytes in different ovarian segments. Conclusion. Determination of frequency distribution of oocytes at different maturity phases can therefore be achieved with the less time- and labour-intensive method of using Abercrombie′s formula.