A study of granulated metrial gland cells in the pregnant mouse uterus

A study has been made of the granulated metrial gland cells of the mouse uterus in pregnancy. The granulated cells are large, often binucleate and typically contain many glycoprotein granules and glycogen. C-esterase activity was found in association with the granules of the granulated metrial gland cells in both mice and rats but this did not appear to be associated with the granule matrix. This does not support previous suggestions that the granules are lysosomal in nature. Morphological evidence is presented which suggests that the granulated cells of mice arise in situ from a lymphocyte-like precursor. although a time-lapse study proved inconclusive. The distribution and proliferation of granulated metrial gland cells was examined throughout pregnancy. Granulated cells were found in small numbers throughout the endometrium in the pre-implantation uterus but following implantation they were found to differentiate and proliferate only in the decidua basalis and metrial gland where their pattern of distribution showed a close correlation with the development of these tissues. The granulated cells found in the antimesometrial region of the implantation site and the interconceptual uterus at implantation were lost within two days. In the last week of pregnancy extensive degeneration of granulated metrial gland cells occurred, initially in the decidua basalis and then in the metrial gland. Other granulated metrial gland cells appeared to penetrate into the lumiina of blood vessels and many were found in the maternal blood spaces around the trophoblastic giant cells in mid-pregnancy and later in the maternal blood spaces of the labyrinth. It is suggested that this may be of functional importance. Few granulated metrial gland cells were present by day 18 of pregnancy although some persisted into the early post partum period. An investigation was made into the factors which may influence the differentiation of granulated metrial gland cells in the pre-implantation pregnant uterus. The differentiation of the granulated cells appears to be independent of the presence of spermatozoa, seminal fluid or blastocysts but the levels of ovarian hormones may be of importance.