Hippocampal pyramidal cells: the reemergence of cortical lamination.
Bottom Line: Distributions of deep and superficial pyramidal cell dendrites and studies in reeler or sparsely GFP-expressing mice indicate that this also applies to afferent pathways.Histological, neurochemical, and connective differences between deep and superficial neurons may correlate with (patho-) physiological phenomena specific to pyramidal cells at different radial locations.We feel that an appreciation of radial subdivisions in the pyramidal cell layer reminiscent of lamination in other cortical areas may be critical in the interpretation of studies of hippocampal anatomy and function.
Affiliation: Institute of Anatomy, University of Zürich, 8057 Zürich, Switzerland. email@example.comShow MeSH
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Mentions: Zinc. Zinc, located in the synaptic vesicles of a subset of telencephalic boutons, was identified as the endogenous substrate of Timm’s sulphide silver methods, which has frequently been used to illustrate hippocampal layers. Like CaBP-ir cells, zinc-containing neurons exhibit a striking preference for sublayers along the radial axis of the pyramidal cell layer in the rat and mouse (Slomianka and Geneser 1991, 1997; Slomianka 1992). They form a densely packed superficial band within the pyramidal cell layer of CA1 throughout the septotemporal extent of the hippocampus in both species (rat: Figs 4c and 5a). Zinc-containing neurons rendered visible in macaque monkey CA1 by retrograde selenite tracing from the inferotemporal cortex are also located in the superficial part of the pyramidal cell layer (Ichinohe and Rockland 2005). The localization of zinc-containing cells in CA1 suggests a colocalization of calbindin and zinc in these cells. CaBP-ir CA1 pyramidal cells were indeed found to be zinc-containing neurons and vice versa (compare Fig. 4c and d, described in detail in Slomianka et al. 1997). Also, the developmental expression of calbindin-immunoreactivity and the ability to label CA1 pyramidal cells (or dentate granule cells) for zinc appear to coincide temporally (Rami et al. 1987a; Baimbridge 1992; Slomianka and Geneser 1997), which may indicate that the specific cellular properties that depend on the presence of calbindin and zinc become functionally important within the same period of postnatal development.Fig. 5
Affiliation: Institute of Anatomy, University of Zürich, 8057 Zürich, Switzerland. firstname.lastname@example.org