Mitochondrial Particles Seen in Sections

Small particles, a t tached to internal mitochondrial membranes and believed to be concerned with the electron t ranspor t system, have been demonst ra ted in the mi tochondr ia of various vertebra te cells and in insect sarcosomes (4, 5, 9, 12-14). In each instance the mi tochondr ia have been isolated from the cells; while in most studies the mi tochondr ia have been disrupted and negatively stained, in some they have been fixed in osmium tetroxide, formaldehyde, or glutaraldehyde and embedded in Araldite or methacryla te (4, 5). Sj6strand et al. (11), however, consider tha t the particles are artifacts produced by the act ion of the solutions used in the prepara t ion of the mi tochondr ia for negative staining. Andr~ (1) describes granules along the cristae of mi tochondr ia of the spermatocytes of the pulmona te mollusc, Testacella, which he interprets as transverse sections of the filaments seen in the mi tochondr ia l matr ix; these mi tochondr ia had been th rough normal fixation and embedding procedures. In an investigation of developing connective tissue a round the central nervous system of the pupae and adults of the wax moth, Galleria mellonella, I noticed tha t particles were clearly visible on the cristae of the mi tochondr ia of the neurons. T h e mi tochondr ia had been subjected to the rout ine procedures of fixation, embedding, and sectioning.