title: Mitotic neuroblasts in the 9-day-old and 11-month-old rodent hippocampus.
abstract: Ultrastructural identification of mitotic neuronal precursors beneath the basal hippocampal granule cell layer was made using electron micrographs of [3H]thymidine-labeled cells. Ultrathin sections were obtained by a method that allows serial thin sectioning of reembedded sections previously prepared for light microscopic radioautography. The electron microscopic observations reported in this study reveal: (1) that a steady rate of granule cell neurogenesis occurs during the first year of a rodent's life; (2) that newly formed granule neurons in the dentate gyrus of the newborn mouse and adult rat are a result of neuroblast division; and (3) two distinct classes of mitotic cells can be identified during the peak period of postnatal neurogenesis--those with synapses on their cell bodies and processes and those with no synapses or processes.
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development / Q000648:ultrastructure*; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D008938:Mitosis