Phase-contrast microscopy of the primate retina.

The study of hematoxylin and eosin stained thick sections (15 microns) of the primate retina with the phase-contrast microscope provided a means for the selective demonstration of many cellular structures that could not be resolved with the same degree of detail which was possible when bright-field microscopy was used, or when phase-contrast microscopy was employed to examine unstained material. The H & E-stain greatly enhanced the phase-contrast image, so that cytoplasmic structure, fiber trajectories, and gross synaptic detail of the retina could be demonstrated to better advantage.

Morphometric analysis of autonomic neuropathology in the abdominal sympathetic trunk of the ketonuric diabetic Chinese hamster.

Fibers from the infradiaphragmatic portion of the sympathetic trunk of ketonuric diabetic Chinese hamsters were quantitatively analyzed by light and electron microscopy to determine frequency distribution and numerical density. Myelinated and unmyelinated fibers displayed a significant reduction in diameter which was exacerbated by increased duration of ketonuria. Mean numerical density of myelinated fibers was reduced whereas that of unmyelinated fibers was increased. The alterations in sympathetic nerve populations are believed to be a manifestation of previously observed demyelination and axonal degeneration. On the basis of axon diameter, it appeared that both visceral afferent and efferent fibers were affected. These data strongly suggest that autonomic neuropathology in the sympathetic trunk of the diabetic Chinese hamster may be a critical factor underlying gastrointestinal dysfunction.

Venom yield of the North American coral snake and its clinical significance.

The dry venom yields of 14 North American coral snakes were measured and correlated to the length of the individual snake. There exists a positive linear correlation between the length of the snake and the amount of dried venom elaborated. The results of this experiment show that the North American coral snake is capable of injecting far more venom than has been previously reported in the literature. A large coral snake can produce 20 mg of dried venom, which is equal to approximately four or five lethal doses for human adults. At least ten 10 ml vials of specific North American coral snake antivenin (Wyeth) would be required to neutralize this quantity of venom. The largest yield of 28 mg of dried venom was obtained from an 89.5 cm specimen, representing approximately seven lethal doses and requiring at least fourteen 10 ml vials of antivenin for neutralization. Observations on the envenomation characteristics of this snake are described.

A melanin-containing nucleus associated with the superior cerebellar peduncle in man. Cytomorphometric analysis.

A melanin-containing nucleus in the oral lateral pontine tegmentum is morphometrically described. The griseum is circumscript and well defined, being closely applied to the ventrolateral aspect of the superior cerebellar peduncle, and within the brachiolemniscal trigone. The nucleus contains two statistically discrete cell populations, small pigmented and small nonpigmented perikarya, both of which demonstrate pleomorphic profiles. The extranuclear pigment granula resemble those of the pigmented cells of the ceruleus complex, substantia nigra, and the dorsal motor nucleus of the vagus, and are melanin. In man this griseum is found in the region corresponding to an area in close proximity and in some cases continuous to A7 of Dahlström and Fuxe, also described by numerous investigators in subhuman primates. It is not identical with the nucleus of KOLLIKER and FUSE. It is proposed that the nucleus may be a component of the brain stem catecholamine system in man.

Dissection casts of the human brain.

A simple, inexpensive method of making accurate permanent casts of brain dissections is described. Dissected brain preparations are used to produce silicone rubber molds. Methyl methacrylate is used to make the hard plastic models.

Dentate nucleus of Ateles ater. Cytomorphometric analysis.

A morphometric analysis of the dentate nucleus of A. ater was performed. Numerical cell densities, cell size, and gray cell coefficients were determined. The selection of this primate was predicated upon phylogenetic and cytoarchitectural criteria. This griseum is cytomorphologically identical to the human dentatum. Quantification was made with both phase contrast and bright-field optics. The gray cell coefficients were determined by Haug's point-counting method. The dentate nucleus is characterized by the presence of large and small neurons and the typical three glial elements. The ratio between the numerical cell densities of the large and small cells was 1:1. The oligodendrocytes had the highest numerical cell density, followed by the astrocytes, and the Hortega cells. The total glia index was computed to be 13.14. In the corpus medullare, the oligodendrocytes presented the highest numerical cell density; the numerical cell densities of the Hortega cells and the astrocytes were not significantly different from each other. Linear measurements of the glial nuclei revealed that the astrocytes were the largest of the glial elements, showing no difference in size between gray and white matter. The size of the oligodendrocytes in the dentate nucleus corresponded to their size in the white matter. In the corpus medullare, the Hortega cell nuclei are shorter in length than those found in the gray substance. The gray cell coefficients were transformed into volume percentages. Only 9% of the dentate nucleus is composed of nerve cell perikarya and glial cell nuclei; the glial cell nuclei represent only 2% of the total white matter. The morphometric differences existing between the cellular elements in both gray and white substance is correlated with the functional roles ascribed to the neuroglia in relation to capillary and neuronal density. The glial 'satellites' are predominately oligodendrocytes.