[Light and electron microscopic studies of the structure and histochemistry of the oviduct epithelial cells (pars recta and pars convoluta I, II, III) in Salamandra salamandra (L.) (Amphibia, Urodela)].

The oviduct of the ovoviviparous Salamandra salamandra is differentiated into five readily distinguishable regions (1. pars recta, 2. p. convoluta I, 3. p. convoluta II, 4. p. convoluta III, 5. p. convoluta IV or uterus) due to the structure of its epithelial cells and the carbohydrate histochemistry of their secretory products. The epithelium of region 1-4 is mono-layered and exhibits ciliated and rather undifferentiated cells which both may contain small amounts of secretory material. Large amounts, however, are present in different gland cells restricted to discrete regions of the oviduct: microgranulocytes occur in the p. convoluta I, II, III, microspongiocytes in the p. convoluta II, III, groups of voluminous spongiocytes and granulocytes which form crypts are found in the p. convoluta I (spongiocytes I), in the p. convoluta II (granulocytes), and in the p. convoluta III (spongiocytes II). The uterine epithelium consists of a uniform cell type described elsewhere. All secretory cells contain neutral mucosubstances (in particular the granulocytes and microgranulocytes) and acid mucosubstances with carboxyl- and sulphate-groups. Sulphate ester groups are common in the mucigen globules of the spongiocytes and the microgranulocytes, whereas carboxylgroups and a demonstrable protein component seem to be predominant in the seromucous granulocytes. The secretory product of the microspongiocytes could not be characterized clearly. The ultrastructural features of the gland cells resemble those of other mucus secreting cells. The Golgi apparatus is the most prominent cell organelle of the spongiocytes and granulocytes. In the latter cells granular endoplasmic reticulum is invariable abundant. The secretory granules of all epithelial cells including the content of the vacuoles of the microspongiocytes as well as substances within the dictyosomes and associated vesicles are stained with the periodic acid--chromic acid--methenamine silver (PACAMS) technique suggesting periodic acid-reactive carbohydrate components. The oviducal gland cells of all pregnant and non-pregnant females investigated--specimens immediately after deposition of the jelly envelopes of the eggs could not be examined during this study--are filled with secretory material. It appears to be discharged at least by the spongiocytes and granulocytes into the lumen of the oviduct also beyond the time of secreting the jelly layers.