AN INTRA-EPITHELIAL GRANULAR CELL IN THE UTERINE EPITHELIUM OF SOME RUMINANT SPECIES DURING THE PREGNANCY CYCLE

Abstract

A cell, which in this paper is assigned the name "intra-epithelial granular cell", has been observed in large numbers within the maternal epithelium of the inter-cotyledonary regions of the placentae of eight ruminant species. The cell is almost exclusively intra-epithelial in position and except in one species is absent from the placentome regions of the placenta. There is a very substantial increase in the number of intra-epithelial granular cells as pregnancy proceeds. The morphology and some of the staining affinities of this cell are described. Morphological considerations suggest a relationship between the intra-epithelial granular cell and the lymphocyte series of cells. Evidence which favours an origin from small lymphocytes is presented. Similarities between the intra-epithelial granular cells of the sheep uterus and the Schollenleukozyten of the sheep gastro-intestinal tract are discussed. Morphological features distinguishing these two granular cells are described. The available data concerning these two cell types is assessed as too incomplete to warrant assuming a relationship between these cells at the present time. Conditions prevailing during gestation evidently stimulate the development of these cells in the uterus. The non-pregnant state has not been extensively studied, but in six non-pregnant sexually mature sheep uteri examined, the granular cells were small in size and few in number. The role of the intra-epithelial granular cell remains undetermined.