A study of the so-called neurotization of nevi.

Fourteen nevi with neuroid zones were examined and compared with nine nevi without neuroid structures. At light microscopic level, nevus cells from the neuroid nevi and the control nevi show the same staining pattern with polyclonal antibodies against S-100 protein. Around the cells of the neuroid zones is a more intensive immunoreactivity with monoclonal antibodies against laminin and collagen type IV than around the nevus cells in the upper dermis and the nevus cells in the control nevi. Also, the Gordon-Sweet stain for reticulin shows a dense network around the cells of the neuroid zones. No immunoreactivity in the neuroid zones was found with monoclonal antibodies against myelin-basic protein, myelin-associated protein, and glial fibrillary acidic protein. At the electron microscopic level, nevus cells from the neuroid zones show stacks of elongated cytoplasmic processes surrounded by basal lamina material. This pattern explains the presence of the abundant cytoplasm seen at light microscopy. Because no features of neural or neurolemmal differentiation could be found, the exactitude of the term neurotization can be questioned.

Malnutrition and the heart: a microscopic analysis.

The effect of starvation on heart morphology was studied in the rat after total caloric deprivation. Morphometric analysis in subendocardial and subepicardial regions in the left and right ventricle was performed before and after starvation. A progressive fall in body weight was noted together with a biphasic change in ventricular weight. The ratio heart/body weight showed a continuous rise initially but stabilized at high levels in the later stage of starvation (p less than or equal to 0.005). The observed changes were analogous in the right and left ventricle. After starvation a significant increase in myocyte volume fraction was noted (p less than or equal to 0.01), but no regional differences were observed with respect to subendocardial-subepicardial and right-left ventricular zone comparison. The change in the non-myocyte fraction is situated in the vascular space and connective tissue. The volume fraction of non-capillary interstitial connective tissue, however, is significantly greater in the right ventricle than in the left (p less than or equal to 0.005). We conclude that in total starvation, after an initial rapid decline in heart weight, the heart is relatively spared. This leads to a rising heart/body weight ratio, until the later stage of malnutrition when the heart undergoes a hypotrophy to the same extent as other organs. This hypotrophy gives rise to a relative increase in myocyte volume fraction and a parallel decrease in capillary volume without major changes in the interstitial non-capillary connective tissue compartment.