title: Secondary expansion of the transient subplate zone in the developing cerebrum of human and nonhuman primates.
abstract: The subplate (SP) was the last cellular compartment added to the Boulder Committee's list of transient embryonic zones [Bystron I, Blakemore C, Rakic P (2008) Nature Rev Neurosci 9(2):110-122]. It is highly developed in human and nonhuman primates, but its origin, mode, and dynamics of development, resolution, and eventual extinction are not well understood because human postmortem tissue offers only static descriptive data, and mice cannot serve as an adequate experimental model for the distinct regional differences in primates. Here, we take advantage of the large and slowly developing SP in macaque monkey to examine the origin, settling pattern, and subsequent dispersion of the SP neurons in primates. Monkey embryos exposed to the radioactive DNA replication marker tritiated thymidine ([(3)H]dT, or TdR) at early embryonic ages were killed at different intervals postinjection to follow postmitotic cells' positional changes. As expected in primates, most SP neurons generated in the ventricular zone initially migrate radially, together with prospective layer 6 neurons. Surprisingly, mostly during midgestation, SP cells become secondarily displaced and widespread into the expanding SP zone, which becomes particularly wide subjacent to the association cortical areas and underneath the summit of its folia. We found that invasion of monoamine, basal forebrain, thalamocortical, and corticocortical axons is mainly responsible for this region-dependent passive dispersion of the SP cells. Histologic and immunohistochemical comparison with the human SP at corresponding fetal ages indicates that the same developmental events occur in both primate species.
authors: Department of Neuroscience, Yale University, New Haven, CT 06510; Kavli Institute for Neuroscience, School of Medicine, Yale University, New Haven, CT 06510;
authors: Alvaro
authors: A
authors: Duque
authors: Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb 10000, Croatia.
authors: Zeljka
authors: Z
authors: Krsnik
authors: Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb 10000, Croatia.
authors: Ivica
authors: I
authors: Kostović
authors: Department of Neuroscience, Yale University, New Haven, CT 06510; Kavli Institute for Neuroscience, School of Medicine, Yale University, New Haven, CT 06510; pasko.rakic@yale.edu.
authors: Pasko
authors: P
authors: Rakic
mesh_terms: D000818:Animals; D019070:Cell Lineage / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D002540:Cerebral Cortex / Q000166:cytology* / Q000196:embryology*; D005865:Gestational Age; D006801:Humans; D008251:Macaca; D008253:Macaca mulatta; D055495:Neurogenesis; D009474:Neurons / Q000502:physiology*
keywords: brain evolution; cerebral cortex; neural stem cells; neuronal migration; transient lamination