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Neurogenesis in the olfactory tubercle and islands of Calleja in the rat
Author(s) -
Bayer Shirley A.
Publication year - 1985
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/0736-5748(85)90004-8
Subject(s) - olfactory tubercle , neurogenesis , thymidine , offspring , biology , tubercle , endocrinology , medicine , anatomy , microbiology and biotechnology , olfactory bulb , central nervous system , biochemistry , pregnancy , genetics , dna , bacteria , bacilli
Abstract Neurogenesis in the rat olfactory tubercle and islands of Calleja was examined with [ 3 H]thymidine autoradiography. Animals in the prenatal groups were the offspring of pregnant females given an injection of [ 3 H]thymidine on two consecutive gestational days. Ten groups of embryos (E) were exposed to [ 3 H]thymidine on E12–E13, E13–E14 4 E21–E22, respectively. Three groups of postnatal animals (P) were given four consecutive injections of [ 3 H]thymidine on P0–P3, P2–P5, and P4–P7, respectively. On P60, the percentage of labeled cells and the proportion of cells originating during either 24 or 48 h periods were quantified at several anatomical levels. Three populations of neurons were studied: (1) large cells in layer III, (2) small to medium‐sized cells in layers II and III, and in the striatal bridges, (3) granule cells in the islands of Calleja. Neurogenesis is sequential between these three populations with No. 1 oldest and No. 3 youngest. The large neurons in layer III originate mainly between E13 and E16 in a strong lateral‐to‐medial gradient. Neurons in population No. 2 are generated between E15 and E20, also in a lateral‐to‐medial gradient; neurogenesis is simultaneous along the superficialdeep plane. Granule cells in the smaller islands of Calleja are generated between E17 and E22 in combined lateral‐to‐medial and superficial‐to‐deep gradients. Neurons in the large island of Calleja are generated mainly between E19 and E22 in a strong rostral‐to‐caudal gradient. Neurogenesis is reduced to < 10% in both populations No. 2 and No. 3, occurring mainly between P0 and P4. The neurogenetic patterns in populations No. 2 and No. 3 are similar to those in the striatum, while neurogenesis in population No. 1 fits into the pattern of the globus pallidus and substantia innominata. These developmental patterns indicate that the olfactory tubercle is a mixed striato‐pallidal system rather than an olfactory cortical area. The lateral‐to‐medial neurogenetic gradient shown in each neuronal population in the olfactory tubercle correlates with both differential anatomical projections and differential neurochemical characteristics along the lateral‐medial plane.