The secretory activity of the epithelium of the ampulla tubae in cyclic ewes: a light microscopical study.

The epithelium of the ampulla tubae of the Texel ewe was studied during the oestrous cycle by light microscopy. A number of ewes was slaughtered on each day of the cycle (D 0 first day of heat). The epithelial height was greatest during the period from D 16 - D 4 and decreased gradually to a minimum on D 7. The intracellular position of the nuclei of the secretory cells appeared to depend on the phase of the cycle. During late metoestrus and dioestrus they were in the cytoplasmic protrusions. It is suggested that these phenomena are consequences of a slowly diminishing oestrogen influence on the epithelium. On D 16 a sharp rise in epithelial height was noticed together with the sudden withdrawal of the nuclei from the cytoplasmic protrusions, probably caused by the increased oestradiol secretion on that day of the cycle. The storage in the cell of a PAS positive material, which appeared to be a mucoprotein, was minimal during pro-oestrus and oestrus and maximal between D 2 and D 7. During dioestrus the cells became gradually depleted of secretum. A hypothesis relating the blood levels of ovarian steroids with the synthesis and release of oviductal secretions is discussed.