[Changes in the morphology of nuclei in the oviduct epithelium of the cow during the estrous cycle].

The changes in the structure of nuclei and nucleoli are good markers of the changes in the activity of epithelium cells of oviducts in cows during the sexual cycle. They are manifested by the changes in the proportion of condensed chromatin and interchromatin. In the secretory as well as ciliary cells, the maximum proportion of interchromatin is recorded in pro-oestrus and oestrus, whereas in metoestrus it is the proportion of condensed chromatin that increases. Metoestrus is characterized by the segregation of nucleoli and by the formation of ring-like nucleoli which partially persist also in dioestrus and in some cells throughout the cycle. Invaginations of the nuclear membrane (which are levelled off later) occur on many nuclei at the end of metoestrus and in dioestrus. Single nuclear bodies occur in the nuclei and the frequency of the the occurrence of interchromatin granules changes. Dilation of perinuclear spaces can be observed in the secretory cells, mainly in the period of oestrus.