Cell death in the developing olfactory epithelium of rat embryos.

Cell death process in the developing olfactory epithelium was studied by light and electron microscopy in rat embryos from embryonic days 12-18. A massive wave of cell death was observed at embryonic days 12 and 13 and two types of dying cells were seen coexisting. The first type of dying cells exhibited morphological features of apoptosis while the second showed characteristics of a cell death by non-lysosomal disintegration with cytoplasmic swelling and absence of phagocytosis. From embryonic day 14 onward, only apoptotic figures could be still occasionally observed. The significance of such a massive wave of cell death occurring during the earliest developmental stages of the rat olfactory epithelium is discussed in relation with the morphogenesis of the olfactory system.