RESUMO
Glutamatergic mossy cells (MCs) mediate associational and commissural connectivity, exhibiting significant heterogeneity along the septotemporal axis of the mouse dentate gyrus (DG). However, it remains unclear whether the neuronal features of MCs are conserved across mammals. This study compares the neuroanatomy of MCs in the DG of mice and monkeys. The MC marker, calretinin, distinguishes two subpopulations: septal and temporal. Dual-colored fluorescence labeling is utilized to compare the axonal projection patterns of these subpopulations. In both mice and monkeys, septal and temporal MCs project axons across the longitudinal axis of the ipsilateral DG, indicating conserved associational projections. However, unlike in mice, no MC subpopulations in monkeys make commissural projections to the contralateral DG. In monkeys, temporal MCs send associational fibers exclusively to the inner molecular layer, while septal MCs give rise to wide axonal projections spanning multiple molecular layers, akin to equivalent MC subpopulations in mice. Despite conserved septotemporal heterogeneity, interspecies differences are observed in the topological organization of septal MCs, particularly in the relative axonal density in each molecular layer along the septotemporal axis of the DG. In summary, this comparative analysis sheds light on both conserved and divergent features of MCs in the DG of mice and monkeys. These findings have implications for understanding functional differentiation along the septotemporal axis of the DG and contribute to our knowledge of the anatomical evolution of the DG circuit in mammals.
Assuntos
Axônios , Calbindina 2 , Giro Denteado , Camundongos Endogâmicos C57BL , Animais , Masculino , Giro Denteado/citologia , Giro Denteado/anatomia & histologia , Calbindina 2/metabolismo , Fibras Musgosas Hipocampais/fisiologia , Camundongos , Especificidade da Espécie , FemininoRESUMO
Se realizó un estudio descriptivo, observacional y transversal en 160 cortes histológicos de la fascia dentada del hipocampo de ratones BALB/c y ratas Wistar blancas, en el Laboratorio de Investigaciones Biomédicas de la Universidad de Ciencias Médicas de Santiago de Cuba, de septiembre de 2013 a igual mes de 2014, con vistas a determinar las transformaciones histológicas que ocurren en dicha fascia en el segundo y sexto días posnatales. La observación microscópica de estos cortes se realizó empleando del software Image J. La extensión de la fascia al sexto día de vida llegó a ser mayor en los ratones; los máximos incrementos del grosor en ambos tipos de roedores se encontraron en el hilus, y el estrato granuloso fue de menor crecimiento en las ratas. La celularidad en los roedores presentó mayores proporciones en las tres regiones del hilus al segundo día, pero disminuyó en el sexto día, mientras que las zonas relacionadas con el hilus mantuvieron una mayor cantidad de células; sin embargo, el número celular disminuyó en ambas regiones moleculares de la fascia de las ratas.
A descriptive, observational and cross-sectional study was carried out in 160 histological cuts of the hippocampus fascia dentata from mice BALB/c and rats white Wistar, in the Laboratory of Biomedical Investigations from Santiago de Cuba Medical University, from September, 2013 to the same month in 2014, with the aim of determining the histological transformations that take place in this fascia in the second and sixth posnatal days. The microscopic observation of these cuts was carried out using the software Image J. The extension of the fascia at the sixth day of life was larger in the mice; the maximum increases of thickness in both types of rodents were in the hilus, and the granular stratum was of smaller growth in rats. The celularity in the rodents presented larger proportions in the three regions from the hilus at the second day, but it decreased at the sixth day, while the areas related to the hilus maintained a greater quantity of cells; however, the cellular number diminished in both molecular regions of the rats fascia.