Fine structural and cytochemical observations on lamellar bodies in nerve cells of the medulla oblongata of the rat.

Stuctures identified as lamellar bodies have observed in neurons of the dorsal sensory nucleus of the vagus of the rat medulla oblongata. They consist of stacks of parallel, regularly spaced cisternae which either run straight or curve forming a whorl. Finely textured, electron-dense fibrils are present between adjacent cisternae which are devoid of ribosomes. Ribosomes are attached only to the outermost surface of outer cisternae which are often continous with rough endoplasmic reticulum. Cytochemical studies reveal that these intercisternal fibrils contain abundant amino and imidazole groups as well as carboxyl groups. It is suggested that lamelar bodies arise by close alignment of parallel rough surfaced cisternae with subsqent loss of ribosomes from their surface. In addition, it is inferred that polar groups of intercisternal fibrils play an important role in the regular arrangement of cisternal membranes and in the dissociation of ribosomes from cisternae.