title: Distinction in the immunoreactivities of two calcium-binding proteins and neuronal birthdates in the first and higher-order somatosensory thalamic nuclei of mice: Evolutionary implications.
abstract: Comparative embryonic studies are the most effective way to discern phylogenetic changes. To gain insight into the constitution and evolution of mammalian somatosensory thalamic nuclei, we first studied how calbindin (CB) and parvalbumin (PV) immunoreactivities appear during embryonic development in the first-order relaying somatosensory nuclei, i.e., the ventral posteromedial (VPM) and posterolateral (VPL) nuclei, and their neighboring higher-order modulatory regions, including the ventromedial or ventrolateral nucleus, posterior, and the reticular nucleus. The results indicated that cell bodies that were immunoreactive for CB were found earlier (embryonic day 12 [E12]) in the dorsal thalamus than were cells positive for PV (E14), and the adult somatosensory thalamus was characterized by complementary CB and PV distributions with PV dominance in the first-order relaying nuclei and CB dominance in the higher-order regions. We then labeled proliferating cells with [(3) H]-thymidine from E11 to 19 and found that the onset of neurogenesis began later (E12) in the first-order relaying nuclei than in the higher-order regions (E11). Using double-labeling with [(3) H]-thymidine autoradiography and CB or PV immunohistochemistry, we found that CB neurons were born earlier (E11-12) than PV neurons (E12-13) in the studied areas. Thus, similar to auditory nuclei, the first and the higher-order somatosensory nuclei exhibited significant distinctions in CB/PV immunohistochemistry and birthdates during embryonic development. These data, combined with the results of a cladistic analysis of the thalamic somatosensory nuclei, are discussed from an evolutionary perspective of sensory nuclei.
authors.affiliation: Beijing Key Laboratory of Gene Resource and Molecular Development, Beijing Normal University, PR China.
authors.forename: Jiang-Yan
authors.initials: JY
authors.lastname: Zhang
authors.affiliation: Beijing Key Laboratory of Gene Resource and Molecular Development, Beijing Normal University, PR China.
authors.forename: Yu-Tao
authors.initials: YT
authors.lastname: Lin
authors.affiliation: Beijing Key Laboratory of Gene Resource and Molecular Development, Beijing Normal University, PR China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Gao
authors.affiliation: Beijing Key Laboratory of Gene Resource and Molecular Development, Beijing Normal University, PR China.
authors.lastname: Chao-Xi
authors.affiliation: College of Life Sciences, Hainan Normal University, Haikou, PR China.
authors.forename: Xue-Bo
authors.initials: XB
authors.lastname: Zhang
authors.affiliation: College of Life Sciences, Hainan Normal University, Haikou, PR China.
authors.forename: Xin-Wen
authors.initials: XW
authors.lastname: Zhang
authors.affiliation: Beijing Key Laboratory of Gene Resource and Molecular Development, Beijing Normal University, PR China.
authors.forename: Shao-Ju
authors.initials: SJ
authors.lastname: Zeng
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001345:Autoradiography; D064026:Calbindins / Q000378:metabolism*; D004622:Embryo, Mammalian; D051379:Mice; D055495:Neurogenesis; D009474:Neurons; D010320:Parvalbumins / Q000378:metabolism*; D013787:Thalamic Nuclei / Q000166:cytology* / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism; D014316:Tritium / Q000378:metabolism
chemical_list: D064026:Calbindins; D010320:Parvalbumins; D014316:Tritium; D013936:Thymidine
keywords: AB_10000340; AB_2174013; brain evolution; core-to-matrix organization; neurogenesis; somatosensory nuclei