Two discrete enkephalinergic neuron systems in the superior cervical ganglion of the guinea pig: an immunoelectron microscopic study.
Leucine-enkephalin (L-ENK)-like immunoreactive (L-ENKI) structures in the superior cervical ganglion (SCG) were first examined by using immunoelectron microscopy. L-ENKI neurons formed cell clusters and were small. They were filled with large granular or agranular vesicles and small electron lucent vesicles, and had nuclei that lacked a nucleolus. Since these morphological characteristics are identical to those of the small intensely fluorescent (SIF) cells, L-ENKI cells seemed to be a kind of SIF cell. Two types of L-ENKI fibers were identified, a large type filled with large granular or agranular vesicles and a small type filled with small electron lucent vesicles. The large fibers were located near the L-ENKI perikarya and often could be traced directly to the soma. These fibers remained intact after decentralization of the SCG. These findings indicate that the large L-ENKI fibers are processes of L-ENKI SIF cells. The fibers showed a close apposition to the blood vessels and rarely formed synaptic contact with dendrites of the principal cells. On the other hand, the small L-ENKI fibers were found to originate outside the SCG, because they disappeared after decentralization of the SCG. These L-ENKI fibers frequently formed synaptic contact with the dendrites of the principal cells. Thus, the present study demonstrated the presence of two discrete L-ENKI neuron systems in the SCG of the guinea pig, one an intrinsic SIF system and the other an extrinsic L-ENKI system.
Matsuyama
T
T
First Department of Internal Medicine, Osaka University Medical School, Japan.
Wanaka
A
A
Kanagawa
Y
Y
Yoneda
S
S
Kimura
K
K
Hayakawa
T
T
Kamada
T
T
Tohyama
M
M
D000818:Animals; D004743:Enkephalin, Leucine / Q000032:analysis*; D005728:Ganglia, Sympathetic / Q000032:analysis* / Q000648:ultrastructure; D006168:Guinea Pigs; D006651:Histocytochemistry; D007158:Immunologic Techniques; D008297:Male; D008854:Microscopy, Electron; D009474:Neurons / Q000032:analysis* / Q000145:classification / Q000648:ultrastructure
D004743:Enkephalin, Leucine