A basis for the interpretation of the structure of the cell membrane is often looked for in electron microscope investigations on the structure of lipid models. A difficulty in these investigations is our lack of knowledge of the effect of the preparative treatment on the structure studied. This applies especially to the strongly oxidizing fixatives: osmium tetroxide and potassium permanganate....

The human epidermis has been studied by electron microscopy following osmium tetroxide and potassium permanganate fixation. An anatomically distinct cell in the human epidermis has been demonstrated with features similar to the melanocyte of the hair bulb described by Barnicot, Birbeck and Cuckow (3). It is dendritic in form and does not contain tonofilaments. "Intercellular bridges" are not fo...

In an evaluation of procedures explored to circumvent some of the problems of osmium tetroxide-fixation and methacrylate embedding of plant materials, excised segments of root tips of Zea mays were fixed for electron microscopy in potassium permanganate in the following treatment variations: unbuffered and veronal-acetate buffered solutions of 0.6, 2.0, and 5.0 per cent KMnO(4) at pH 5.0, 6.0, ...

Heightened interest in the cytology of certain free-living flatworms has been evident in the literature throughout the past year (5, 6, 10-12). The variety of problems dealt with by various investigators reflects the abundance of curious cellular specialization found in this group of animals. Moreover, the suitability of the Turbellarians for the study of regenerative processes is well recogniz...

During the early phases of tissue sectioning for electron microscopy, virtually all of the standard cytological fixatives were tried. Of these, osmium tetroxide appeared to give the best preservation, and this was further improved by buffering the fixative solution at a slightly alkaline pH (Palade (1)). A variant developed by Dalton (2) contains Os04 in a chromate-dichromate system. Formalin h...

A morphological investigation of mitochondria within the seminal epithelial cells of rat testes fixed in potassium permanganate reveals differences in electron opacity between the internal mitochondrial membranes of spermatogenic cells and those of Sertoli cells. Some interpretations of the apparent density differences are briefly discussed. It is concluded that the different effects of permang...

Alkaline phosphatase may be used as a label for immunocytochemistry and can be demonstrated in tissue sections using the single step naphthol phosphate method. Endogenous enzyme activity may not be destroyed by fixation in formalin, formol alcohol, Carnoy's or Baker's solutions and should be inhibited before results are assessed. Either Bouin's solution or periodic acid followed by potassium bo...

The fixation of rat pancreas in potassium permanganate according to Luft (1) imparts a brown coloration and a strong ultraviolet absorption to the cytoplasm of the exocrine cells, but only a weak one to the nuclei. Within the latter an even paler zone surrounding the nucleoli can be observed. After the removal of the stain by means of oxalic acid, ultraviolet microscopy and the Feulgen technic ...