Control

Abstract

Analysing the control of GMG cells involves considering a number of aspects covering the supply of precursor cells in the bone marrow and their emigration, their immigration into the uterus and their subsequent differentiation into, and proliferation as, GMG cells. In addition the emigration of some GMG cells from the decidua basalis and metrial gland and the death of GMG cells, instead of or after emigration, are all events over which some degree of control probably exists. Not only are there many aspects in the life and death of GMG cells which may be controlled by external factors but it is likely that the control is multifactorial. Consideration must be given to a role for seminal fluid and spermatozoa, and to the products of conception at various stages of their development. In addition, the hormones of pregnancy acting directly or indirectly are probably important factors in the control of GMG cells and recently attention has focussed on the possibility that factors provided by stromal cells are involved in the differentiation of GMG cells (Stewart 1983, 1987c).