A study of granulated metrial gland cells in the pregnant, alymphoplasia (aly/aly) mice.

During pregnancy, a population of uterine NK cells, commonly called granulated metrial gland (GMG) cells, differentiates in the uterus of both immune competent and various immunodeficient mice. Regulatory mechanisms controlling the differentiation of GMG cells are not fully known. It has been proven that GMG cells are derived from bone marrow, appear under the influences of progesterone and estrogen, do not require the presence of an embryo, and are associated in rodents with decidualization of the uterine stroma. Mice of genotype aly/aly are genetically deficient in lymph nodes and Peyer's patches due to a lymphoid-associated mesenchymal disorder. They are considered to be a useful model for the study of interactions between lymphocytes and stromal components. This immunodeficient animal is completely different from nu/nu and scid/scid mice who differentiate GMG cells during pregnancy. To determine whether the differentiation of GMG cells depends on mesenchymal interactions in the uterus, aly/aly mice were studied histologically between days 10 and 14 of pregnancy for differentiation of GMG cells and development of the metrial gland. Metrial gland tissue was present and appeared normal in aly/aly mice. There were no significant differences in the distribution of GMG cells in comparison to control pregnant aly/+ mice. Fewer GMG cells were present in aly/aly mice than aly/+ mice on days 12 and 14 of pregnancy. The features of individual GMG cells were different on days 10 and 12 of pregnancy. GMG cells in aly/aly mice were small in size and the granules were poorly developed. By day 14, however, GMG cells acquired a mature size and the granules appeared mature. It is likely that GMG cell differentiation was delayed in pregnant aly/aly mice, due to a mesenchymal disorder affecting metrial gland development in this animal.