title: Reelin-expressing neurons in the postnatal and adult human hippocampal formation.
abstract: Reelin plays a major role in the development of laminated brain structures. In the developing neocortex and hippocampus, Reelin is secreted by Cajal-Retzius cells in the marginal zone. In the present report, we characterize Reelin-immunoreactive neurons in the perinatal and adult human hippocampal formation. Two main populations of cells are described: Cajal-Retzius cells and interneurons. Cajal-Retzius cells are defined as neurons that coexpress Reelin and p73, a nuclear protein of the p53 family. Colocalization experiments of p73 with calcium-binding proteins indicate that most Cajal-Retzius cells express calretinin, but not calbindin. Cajal-Retzius cell density decreases dramatically during the postnatal period, although a few Reelin/p73-positive neurons are still found in the adult. At birth, Reelin-positive, p73-negative neurons are present in all layers of the hippocampal formation. Their morphology and localization indicate that they belong to a heterogeneous population of interneurons. They are numerous in the strata lacunosum-moleculare and radiatum of CA1-CA3, in the hilus, and in the molecular layer of the dentate gyrus, but less common in stratum oriens and alveus, and rare in the principal cell layers. Subpopulations of Reelin-positive interneurons express calretinin or calbindin. The packing density of Reelin-positive cells decreases postnatally, which may be related to the disappearance of Cajal-Retzius cells and to the growth of the hippocampal formation. The presence of Reelin-immunoreactive cells in the adult hippocampal formation indicates that Reelin is not restricted to development but that it may have additional functions in adult life.
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of La Laguna, La Laguna, Tenerife, Spain.
authors.forename: Hajnalka
authors.initials: H
authors.lastname: Abraham
authors.forename: Gundela
authors.initials: G
authors.lastname: Meyer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D017209:Apoptosis / Q000502:physiology; D064032:Calbindin 2; D064026:Calbindins; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism*; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology*; D048429:Cell Size / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D018891:Dentate Gyrus / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005260:Female; D016147:Genes, Tumor Suppressor; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007395:Interneurons / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D000091042:Reelin Protein; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D012697:Serine Endopeptidases; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins
chemical_list: C576764:CALB2 protein, human; D064032:Calbindin 2; D064026:Calbindins; D015816:Cell Adhesion Molecules, Neuronal; D004268:DNA-Binding Proteins; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D000091042:Reelin Protein; D064030:S100 Calcium Binding Protein G; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; C000717127:RELN protein, human; D012697:Serine Endopeptidases