According to their degree of morphological specialization, the cell populations of the brain stem may be classified into three groups: isodendritic, allo-dendritic and idiodendritic. The isodendritic neurons, or generalized neurons, are the most frequently encountered. If one discards those isodendritic centers that by common definition are sensory or motor, an isodendritic core is left which displays very little histological variation throughout the whole extent of the brain stem. This core corresponds, with certain restrictions, to the regions that are usually regarded as reticular formation. It constitutes a continuum of overlapping dendritic fields that extends from the spinal cord to the diencephalon. In view of the similarities that exist between the histology of the isodendritic core and the relatively disorganized nervous system of the lower vertebrates, it is postulated that it represents a pool of pluri-potential neurons which in the course of phylogeny have remained relatively undifferentiated and in charge of processing afferent signals of very heterogeneous origin. By contrast, the allodendritic and idiodendritic centers can be regarded as relatively specialized centers from the point of view of their dendritic morphology, connections and functions. Attention is paid to the fact that the diffuse characteristics of the isodendritic core do not necessarily entail ill-defined physiological properties.

The isodendritic core of the brain stem

Cell clusters in the nucleus accumbens of the rat, and the mosaic relationship of opiate receptors, acetylcholinesterase and subcortical afferent terminations

The amygdaloid complex in the cat was studied in a series of Golgi preparations. Both the lateral and the basal nucleus are composed of the same two cell types, one of which (type P) resembles the pyramidal and the other (type S) the stellate neuron of the cortex. The cortical nucleus can be divided into three layers (I, II, and III–IV) which are made up of cells similar to those in the periamygdaloid cortex. In addition, there are sufficient differences in the organization of these layers to justify a subdivision of the cortical nucleus into lateral and medial parts. The dendrites of neurons in the medial part of the central nucleus, the medial nucleus and the anterior amygdaloid area undergo less branching and carry fewer spines than those of the type P cell. The neurons in the nucleus of the lateral olfactory tract are all of the pyramidal or modified pyramidal type. These findings are discussed in relation to those of previous investigators who employed the Nissl and Golgi methods.

The amygdala of the cat: a Golgi study.

On columnar arrangement of nerve cells in cerebral cortex

Chapter 4 – The Methods of Golgi

Celloidin blocks of Golgi-Cox impregnated material are cut at 50 μ, the sections collected in 70% alcohol, transferred to a 3:1 mixture of absolute alcohol and chloroform for 2 min, and then stored in xylene or toluene for at least 3 min, or up to 2 wk until processed further. Mounting is done on glass slides which have been coated with fresh egg albumen diluted in 0.2% ammonia water (or a 0.5% solution of dry powdered egg albumen) and then dried at 60°C overnight. For attachment to these coated slides, sections are first soaked for 2-3 min in a freshly prepared mixture of methyl benzoate, 50 ml; benzyl alcohol, 200 ml; chloroform, 150 ml; and then transferred quickly to the slides by means of a brush. After 2-3 min the chloroform evaporates and the celloidin softens. The slides are then immersed in toluene which hardens the celloidin and anchors the sections to the slides. Alcohols of descending concentrations to 40% are followed by alkalinizations, first in: absolute alcohol, 40 ml; strong ammonia water...

E. Ramon-moliner

Papers

Basic dye counterstaining of sections impregnated by the golgi-cox method.