Stereological study of the synaptic profiles belonging to interneurons in the dorsal lateral geniculate nucleus of the rabbit.

This study is concerned with some characteristics of the interneurons belonging to the dLGN (dorsal Lateral Geniculate Nucleus) of the rabbit. The work deals with the distribution of such cells in the alpha E sector of the nucleus and their F1 and F2 presynaptic contacts. The F1 and the F2 profiles are present in all three of the alpha E zones studied. The F1 profiles are significantly more numerous in the upper zone (57 +/- 2 profiles per 10(4) microns2 of section) and the middle zone (59 +/- 3 profiles per 10(4) microns2 of section) than in the lower one (41 +/- 2 profiles per 10(4) microns2 of section). The F2 profiles are more abundant in the alpha E sector than the F1 ones are, particularly in the lower zone, where F2 profiles (104 +/- 4 profiles per 10(4) microns2 of section) are not only significantly more numerous than F1 profiles but also more abundant than the F2 profiles in the middle zone (84 +/- 3 profiles per 10(4) microns2 of section) and upper zone (88 +/- 2 profiles per 10(4) microns2 of section). These results and their comments reveal diverse density of the element distribution from the dorsal to the ventral part of the alpha E sector as well as the possible relationship or independence from the extranuclear afferent inputs.

Cytoarchitecture of the dorsal lateral geniculate nucleus in the rabbit.

The cytoarchitecture and morphometry of the neurons in the alpha E sector of the dorsal lateral geniculate nucleus of the rabbit have been studied. The preparation techniques used were those of Golgi-Adams and Klüver-Barrera. Our method was to subdivide the alpha E sector into three zones (superior, medial and inferior) and then to cut each zone along the horizontal, transverse and saggital planes in order to obtain precise measurements and descriptions of the neurons whatever their orientation. Differences exist in both the size and distribution of neurons in the inferior zone of the alpha E sector compared to the other two.

A modification of the chronic tartrate silver impregnation technique for block impregnation of the central nervous system and paraffin wax embedding.

This paper describes a block silver impregnation technique for the CNS. The procedure, which is quite simple, yields highly consistent and reproducible results. After fixation during 6-10 days in 10% saline formaldehyde, 4 mm thick blocks of brain are treated with chromic anhydride and sodium potassium tartrate solution for 4 days. After this period the specimens are rinsed in 0.75% silver nitrate solution to which 8-10 drops of pyridine per 100 ml of solution have been added. This is followed by impregnation for 4 days at 37 degrees C in silver nitrate-pyridine solution identical to that used in the previous rinsing step. The impregnated blocks are reduced during 20-26 h in 1% pyrogallol to which 6 ml commercial formaldehyde per 100 ml of solution have been added, followed by dehydration in dioxan and paraffin embedding. Sections no thicker than 30 microns are then cut for histological study. This fundamentally neurofibrillar method reveals: neuronal somata and their processes; synaptic structures; fibre bundles; and cell nuclei and nucleoli.