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An ultrastructural study of the red nucleus in the rat
Author(s) -
Reid J. M.,
Flumerfelt B. A.,
Gwyn D. G.
Publication year - 1975
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.901620306
Subject(s) - golgi apparatus , endoplasmic reticulum , ultrastructure , biology , nucleus , nuclear membrane , vesicle , electron microscope , synaptic vesicle , microbiology and biotechnology , biophysics , anatomy , membrane , biochemistry , physics , optics
The red nuclei of 14 adult male rats of the Wistar strain were prepared for electron microscopic study following perfusion with a mixture of aldehydes. Neurons of four size categories were identified in 1 μ Epon sections and their ultrastructural characteristics were studied in adjacent thin sections. Giant ( >40 μ) and large (20–40 μ) neurons are distinguished primarily by size and possess similar ultrastructural features: extensive areas of rough endoplasmic reticulum (RER), a prominent perinuclear Golgi complex, numerous mitochondria and pigment granules and a large, ovoid nucleus which occasionally contains intranuclear rodlets. Medium size neurons (20–25 μ) have less extensive, poorly organized RER and randomly distributed Golgi complexes. The nuclear envelopes of these cells fraquently show multiple invaginations and continuity with the RER cisternae. In small neurons (<20μ) the RER occurs as single or anastomosing strands while Golgi complexes and pigment granules are few. In both medium size and small neurons, aggregates of condensed chromatin are adherent to the inner nuclear membrane. Three main types of synaptic terminals may be distinguished in the red nucleus: (1) small terminals with flattened vesicles and symmetrical densties (F terminals), (2) small terminals with rounded vesicles and asymmetrical densities (RS terminals), and (3) large (10–15 μ) asymmetrical, rounded vesical terminals which form multiple contacts along their length (RL terminals). The small neurons receive both F and RS terminals on their dendrites and infrequently on their cell somes. The large and giant neurons receive F, RS and RL terminals on their somes and proximal dendrites and F and RS terminals on their distal dendrites. The somas and dendrites of medium size neurons receive both F and RS terminals but RL terminals do not lie in relation to them. Spine contacts are common throughout the nucleus and occur on both somas and dendrites.