MORPHOLOGICAL STUDIES ON THE TECTAL CELLS PROJECTING TO NUCLEUS ROTUNDUS IN THE CHICK / 解剖学报

ABSTRACT

Objective To study the morphological characteristics of tectal cells in stratum griseum centrale(SGC) which project to nucleus rotundus(Rt) in chick. Methods Tectal cells projecting to the Rt were retrogradely labeled by using the injection or implantation of a small amount of carbocyanine fluorescent tracer(DiI) into Rt postmortemly in chicks.Results Labeled SGC cells were classified into four types according to the location of the soma and dendritic endings in the tectal layers.Type 1 cells of the SGC,whose somata were located in superficial part of the SGC,gave off dendritic endings to layer F.Type 2 cells in the SGC,whose somata were also located in superficial part of the SGC,gave off dendritic endings to layer D.Type 3 cells,whose somata were located in deep part of the SGC,gave off primary dendrites obliquely in layer H-J of SGFS.Type 4 SGC cells,whose somata were located in the deep part of the SGC,gave off dendrites horizontally and their dendrites were located within the SGC.The labeled dendrites of type I and 2 cells of the SGC formed bush-like or bifurcated endings extending horizontally in layer F and bottle brush endings vertically in layer D,respectively.The dendrites of type 3 and type 4 cells mainly formed free endings in their extending deep tectal layers.Conclusion The dendrites of superficial SGC cells(type 1 and type 2 cells) extend to retinorecipient tectal layers(layer F and layer D,respectively),having the shape of bush-like or bifurcated endings extending horizontally in layer F and bottle brush endings vertically in layer D,respectively corresponding to the shapes of terminals of optic nerves in these layers.The dendrites of deep SGC cells(type 3 and type 4 cells) do not extend to the retinorecipient tectal layers,mainly forming free endings in the tectal layers deeper than layer H.