ISSN:
0002-9106
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Midbrains of ten young adult rats were sectioned serially in three planes to study the detailed cytoarchitecture of the substantia nigra. These neurons measure 8 to 17 μ in diameter. In comparison, the largest neurons in the midbrain measure 20 to 40 μ; hence, neurons are designated according to size as follows: those measuring 18 to 40 μ, large; 12 to 17 μ, medium; and 8 to 11 μ, small. The substantia nigra of the rat contains non-pigmented neurons in three divisions: pars reticulata, pars compacta, and pars lateralis. The pars reticulata is the largest division and has the longest rostrocaudal extent. It contains neurons of small size medially and of medium size laterally. This finding correlates with described differences in connections. Three-dimensionally, the pars reticulata is an oblate spheroid with the long axis in the rostrocaudal plane. The pars compacta is a triangular layer dorsal to reticulata. It is subdivided into rostral and caudal portions at the level of the fibers of the basal optic root. Neurons in both subdivisions are medium in size, but cells rostrally are darker than those caudally. The pars lateralis is a column of neurons with its long axis located in the rostrocaudal plane. It lies dorsolateral to the pars reticulata and the pars compacta, with occasional connections to both by cellular strands. The pars lateralis has rostral and caudal portions; neurons rostrally are medium in size and round; caudally, however, neurons are variable in size, dark, stellate or fusiform, and have long processes.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aja.1001290404
