Histochemical Examination of the Vaginal Epithelium of Sows at Various Stages of the Estrus Cycle

Abstract

The aim of this study was to histochemically determine the substrates which have a bearing on the carbohydrate metabolism of the vaginal mucosa. Ten multiparous sows of the German Landrace breed were used. Samples were taken from the vagina with a biopsy device throughout the estrus cycle. Increased concentrations of glycoproteins and glycogen occur between proestrus and metestrus. Glycogen in the pig does not reach to vaginal lumen. It is most likely used for the biosynthesis of glycoproteins in deeper layers of the epithelium. Consequently, the drop in p H observed in the vaginal lumen during estrus must result from secretion of acidic glycoproteins by epithelial cells, rather than from the breakdown of glycogen to lactic acid. During proestrus and estrus, the superficial cell-layer of the epithelium secretes mucus. Mucus secretion plays an important role during estrus by supporting phagocytic activity of the neutrophilic granulocytes, and therefore the self-cleaning effect of the vagina. The lamina propria demonstrates cyclical changes as well: fibrocytes in the lamina propria contain increased amounts of cytoplasmic RNA during proestrus and estrus, indicating increased protein synthesis. The protein involved here is most likely a compound of hyaluronic aciJ-cc)ntaining proteolycans, which are deposited in the interfibrous substance. KNA determined histochemically in the fibrocytes of the lamina propria is a reliable criterion for diagnosis of proestrus and cstrus.

Morphological changes in the vaginal epithelium during the oestrous cycle of Calomys callosus (Rodentia, Cricetidae)

“…This leukocyte infiltration is a well known phenomenon and has already been described by various authors (Busch, 1966;Holtz et al, 1968). Thus, by a still unclear mechanism, the leukocytes migrate through the epithelium towards the lumen, assisting in protection from infectious agents (Corbeil et al, 1985), or to accomplish the phagocytosis of spermatozoa residues still present in the vaginal lumen (Branscheid & Holtz, 1988).…”

“…The secretion produced by the epithelial cells is discharged to the vaginal lumen where, together with the secretions from the cervix, seems to perform an important role in the defense of the epithelium, since the leukocytes remain immersed in this gelatinous net, and thus may exert their phagocytic function (Branscheid & Holtz, 1988).…”