Abstract
Membrane structure of phagosomes in the process of fusion with each other or lysosomes was investigated mainly by an ultracytochemical method. It was noted that the glycocalyx-like structure extruding to the luminal sides of phagosomes was absent in the apposed regions of membranes during phagosomal fusion, although it was remarkable in the remainders of phagosomal membranes. Furthermore, reaction products of both ALPase and ACLase activities used as markers representing proteins were not demonstrated there, either. On the other hand, PFP reaction, which has been said to be positive for carbohydrates and unsaturated lipids, caused electron density in the total length of the membranes of phagosomes during fusion. The electron density in apposed membrane regions seemed to be attributed to unsaturated lipid, because glycocalyx-like structure consisting of carbohydrates was absent there. These findings suggest that membranes which are fusing are devoid of most, if not all, carbohydrates and proteins and rich in unsaturated lipids.
