Metrial gland cells in deciduomata of pseudopregnancy

Light and electron microscope studies were carried out on the metrial gland cells of deciduomata of pseudopregnancy in the rat. At the light microscope level these cells were characterised by a comparatively pale staining cytoplasm with numerous glycoprotein granules. Some also had extensive cytoplasmic deposits of glycogen. In electron micrographs the metrial gland cell cytoplasm as a whole was much less electron-dense than that of fibroblasts and decidual cells, but it contained densely stained pleomorphic granules. There were stacks of rough endoplasmic reticulum, oval or round profiles of fibroblasts and decidual cells, but it contained densely stained pleomorphic granules. There were stacks of rough endoplasmic reticulum, oval or round profiles of mitochondria, and an extensive Golgi network. The metrial gland cells were roughly spherical in appearance, with irregular surface projections. In all these features, and in the sequence of their appearance, first in the decidua basalis, and later in the mesometrial triangle, the granulated metrial gland cells of deciduomata resembled the metrial gland cells of pregnancy. In addition to granulated metrial gland cells, decidual cells and fibroblasts, a number of other cell types were identified. These cells could be placed in a series, with each member of the series minimally different in morphological appearances from its neighbours. It is proposed that the series represents the differentiation of granulated metrial gland cells, in situ, from lymphocyte-like cells. The differentiation from a lymphocyte precursor appears to follow a sequence in deciduomata formation similar to that previously described in pregnancy.