Holocrine cell Lysis in the rat preputial sebaceous gland. Evidence of autophagocytosis during cell involution

Abstract

AbstractThe fine morphological and cytochemical (acid phosphatase) changes occurring during holocrine cell lysis in the sebaceous preputial gland of the adult rat were investigated. When cells reach full differentiation cisternae of the widespread rough endoplasmic reticulum show invaginations of the wall. Cytoplasmi areas comprising such altered cisternae, normal RER and some mitochondria, are later sequestered into autophagic vacuoles, either surrounded by a single membrane (type I‐bodies), or by a thick wall formed by concentric membranes (type II‐bodies). Other vacuoles with similarly stratified wall and containing debris and acid phosphatase appear in cells at the next stage of involution. These autophagic vacuoles (type III‐bodies) are probably derived from type II‐bodies, and become gradually transformed into residual bodies rich in myelin figures, while the cell membrane and the nuclear envelope rupture. These findings show that prior to cell disintegration most of the cell cytoplasm, with the exception of the lipid and proteinaceous secretion granules and some mitochondria, is focally degraded within autophagic bodies.