Granulated metrial gland cells at implantation sites of the pregnant mouse uterus.

A study has been made of the distribution of, and synthesis of DNA by, granulated metrial gland cells at implantation sites in the pregnant mouse uterus. Granulated cells were found in small numbers randomly distributed throughout the endometrium on day 4 1/2 of pregnancy. Subsequently cells of this type were lost from the antimesometrial and lateral decidua but increased dramatically in number in the developing decidua basalis. From day 7 1/2 granulated cells populated the mesometrial triangle to form the metrial gland. A high proportion of granulated cells was found to incorporate tritiated thymidine and the distribution of such cells is described. However, no granulated cells were found to incorporate tritiated thymidine at or after day 12 of pregnancy. In addition the loss of granulated metrial gland cells from the implantation site is described and is accounted for by degeneration in situ and also by migration via vascular channels. It is suggested that this latter route could be of functional significance.