Development of Layers in the Dorsal Lateral Geniculate Nucleus in the Tree Shrew

Abstract

Publisher Summary This chapter discusses the features of lamination in the mature dorsal lateral geniculate nucleus (LGN), development of layers in LGN, and the role of retinogeniculate fibers in the development of individual features of lamination. In the absence of cytoarchitectural and cytological features of lamination, most mammals exhibit laminar segregation of retinal input to the LGN. The evaluation of the effect of bilateral enucleation on cytological development is based solely on Nissl-stained material. The formation of spaces between cell layers in the LGN can be compared to the formation of other cytoarchitectural features in different systems. The retinogeniculate fibers have a “trophic” effect on the LGN cells, stimulating dendritic growth, and perhaps other features of differentiation. The combination of dendritic growth of cells in adjacent layers and the dense projection of the corticogeniculate fibers on the distal LGN cell dendrites thus result in the formation of the interlaminar spaces and the laminar projection pattern of the corticogeniculate fibers. The development of cytological features characteristic of individual layers, in the absence of retinogeniculate fibers, is presumably due to a combination of intrinsic cellular differentiation independent of afferent input and, perhaps to some degree of “trophic” stimulation by intact afferent systems such as the late-arriving corticogeniculate projection.