Numbers of metrial gland cells in the maternal placental supply and drainage vessels of Swiss Webster and C57B1 mice.

The number of metrial gland cells in the maternal placental supply vessels was found to be greater in C57B1 than in Swiss Webster mice from the eleventh to the thirteenth day of gestation. Since it has been found previously that the number of these cells lodged in the labyrinth is greater in Swiss Webster than in C57B1 mice, it appears likely that more disintegrate in the C57B1 than in the Swiss Webster strain. However, some cells in both strains were found in the veins draining the placenta and uterine wall and have been observed previously in lung capillaries. Disintegration is not, therefore, the sole mechanism of loss. The increase, with time, in the number of metrial gland cells in the metrial gland portion of the placental supply vessels in both strains suggests that, although there is overlap, the decidua basalis is the early source of migrating metrial gland cells, and that the metrial gland later augments the flow.