Distinctive morphology of hippocampal CA1 terminations in orbital and medial frontal cortex in macaque monkeys.
The fine morphology of hippocampal connections to the orbital and medial frontal cortex (OMFC) was investigated by placing injections of anterograde tracers in the CA1 in two monkeys. The axons terminated mainly in layers 2 and 3, of areas 11, 13, 14c, 25, and 32, and were widely divergent in these layers, traversing 2-4 mm. Boutons were scattered along the main axon, but also occurred as distinctive small, spherical clusters of terminations ("mini-clusters"; diameter <50 microm). Occasional larger terminal arbors were observed in layer 3 and these were often unusually tortuous or convoluted. These features may imply a specialized microcircuitry of hippocampal-OMFC connections, including an origin from a particular subpopulation of CA1 projection neurons.
Zhong
Yong-Mei
YM
Laboratory for Cortical Organization and Systematics, RIKEN Brain Science Institute, 2-1 Hirosawa, 351-0198, Saitama, Wako-shi, Japan.
Yukie
Masao
M
Rockland
Kathleen S
KS
D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D003911:Dextrans / Q000378:metabolism; D005260:Female; D005625:Frontal Lobe / Q000166:cytology*; D006624:Hippocampus / Q000166:cytology* / Q000502:physiology*; D008252:Macaca fascicularis; D009434:Neural Pathways / Q000166:cytology*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D012235:Rhodamines / Q000378:metabolism
D003911:Dextrans; C067661:Fluoro-Ruby; D012235:Rhodamines; C076397:biotinylated dextran amine; D001710:Biotin