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The ultrastructure and organization of methionine‐enkephalin immunoreactive profiles in the interpeduncular nucleus of the cat
Author(s) -
Kapadia Shanta E.,
De Lanerolle Nihal C.
Publication year - 1984
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.902290105
Subject(s) - interpeduncular nucleus , ultrastructure , biology , vesicle , enkephalin , horseradish peroxidase , anatomy , nucleus , immunocytochemistry , neurochemical , midbrain , neuroscience , central nervous system , endocrinology , biochemistry , receptor , membrane , opioid , enzyme
An ultrastructural analysis of the dorso‐intermediate (CDIZ) and dorsomedian zones (CDMZ) at the caudal end of the interpeduncular nucleus was undertaken. Serial vibratome sections were stained for metenkephalin‐like immunoreactivity by using the indirect antibody peroxidase‐antiperoxidase method of Sternberger, and ultrathin sections were examined electron microscopically, Met‐enkephalin‐like immunoreactivity was observed in two different types of somata in the two regions. The dendritic architecture of the dorso‐intermediate zone was characterized by the presence of many dendritic crests. A large number of these dendritic crests were immunostained for metenkephalin. A variety of terminals was also seen in the CDIZ and CDMZ and they are categorized according to their vesicular morphology into three classes. One class contained mainly clear round vesicles. The metenkephalin‐like immunoreactive (MELI) terminal profiles in both regions were of this class and contained small round vesicles which were less than 35 nm in diameter. These MELI terminals appeared in significant numbers, sometimes in close proximity to unlabeled somata and dendrites. The dorso‐median zone had, in addition, two more classes of terminals. One class was characterized by a large number of dense‐cored vesicles—class II, and the other group had a large proportion of flat clear vesicles—class III. The possible neurochemical identities of some of the unlabeled terminals in relation to the MELI dendritic structures are discussed in the light of known neurochemically established afferent projections to the CDIZ and CDMZ of the interpeduncular nucleus.