STUDY ON THE CALLOSAL NEURONS IN THE VISUAL CORTEX OF THE ALBINO RAT BY MEANS OF RETROGRADE TRANSPORT OF HRP / 解剖学报

ABSTRACT

In order to investigate the distribution and other features of callosal neurons inthe visual areas,12 adult albino rats were used in a series of experiments,in whichHRP(30～50%,DAB brown reaction)was injected into one hemisphere and theretrograde labelled cells were observed in the other hemisphere.1.Hardly any labelled neuron was found in contralateral visual cortices whenthe injections were made at sites within 3.6 mm from the midline of the brain.However,when the injections were made at sites 4～6 mm from the midline,manylabelled neurons could be observed.2.Generally,most labelled cells aggregated near the border between area 17 and18a.In area 18a numerous cells were labelled,which distributed in the form ofincontinuous patches.In the proper of area 17,however,less labelled cells werefound.3.A gross topographical correlation was observed between locations of injectionand labelling on the two hemispheres.4.The labelled cells were found in all cortical layers except layer Ⅰ.In area 17they were mainly in layers Ⅳ and Ⅴ,while in area 18 a they were found mainly inlayers Ⅲ,Ⅳ and Ⅴ.5.Some callosal neurons were lightly labelled.For these cells,only the outlinesof the cell body could be seen even under dark-field microscope.The diameters ofthese cells were about 8～10?m.A few cells were as large as 16?m in diameter.Other labelled neurons could be seen with both dark-field and bright-field illumina-tions.They were identified as pyramidal,multipolar bipolar and granular cells accordingto the shape of the cell bodies and the pattern of dendrites.The majority of labelledcells were pyramidal cells,with a long apical dendrite to the pia surface,10～20?min diameter.Other ceils were 10～20?m for multipolar cells,and less than 10?m forgranular cells.Comparisons were made between the above results and the physiological studies.