STUDIES ON THE HEXAPOD NERVOUS SYSTEM. IV. A CYTOLOGICAL AND CYTOCHEMICAL STUDY OF NEURONS AND THEIR INCLUSIONS IN THE BRAIN OF A COCKROACH PERIPLANETA AMERICANA (L.)

Abstract

A wide variety of cytological and cytochemical staining reactions has revealed 3 types of cytoplasmic inclusions which exist in addition to mitochondria, ribosomes, and the Golgi apparatus. These are called A-cell neurosecretorymaterial (NSM), beta-, and delta-granules. A-Cell NSM appears to be a cystine- or cysteine-rich phospholipo-protein. Beta-granules are found in the majority of neurons. Cytochemical data suggest that they contain a lipid or glycolipid, probably in chemical association with a protein. Delta-granules sporadically occur as single, conspicuous inclusions within the perikarya of smaller neurons. They appear to contain phospholipid. The "mottled" appearance of nerve cells which have been stained to demonstrate ribonculeic acid appears due to the unstained Golgi spheroids. The limitations of staining reactions as criteria for categorizing cytoplasmic inclusions, and the significance of cytomorphological features as indices of neurosecretory activity are discussed.