Origins of crossed and uncrossed retinal projections in pigmented and albino XXXX .

@entity19 @entity717 @entity4494 @entity2198
The extent of the binocular cortical field in albino @entity19 , as revealed by recording from single cells, was almost normal; although the input from the ipsilateral eye was weaker than normal, most cells were driven from both eyes. By backfilling retinal @entity4494 cells from one optic tract with horseradish peroxidase we examined the origins of the retinofugal projections. Filled cells ipsilateral to the injected tract were concentrated in a crescent-shaped area bordering the inferior temperal retina. In black @entity19 this area constituted 20% of the total retinal area, in albinos 17%. In black @entity19 we counted nearly 1,000 labeled cells in the @entity717 , or 2.6% of all cells filled in both eyes. Albinos had about one-third fewer filled cells ipsilaterally than black @entity19 . Four percent of all ipsilaterally filled cells in black @entity19 and 8% in albinos were scattered outside of the crescent region. The density of ipsilaterally projecting cells was uniform throughout the crescent region in black @entity19 , but decreased toward the central retina in albinos. In retinas contralateral to the injection up to 39,000 cells were filled-about two-thirds of the cells in the @entity4494 -cell layer whose cytoplasm contained conspicuous Nissl substance. Depending on classification of unfilled cells as @entity4494 cells or interneurons, we estimated a @entity2198 cells to exist in the retina. The size distribution of ipsilaterally projecting @entity4494 cells was similar in albinos and normals. Ipsilaterally projecting @entity4494 cells were on average 1.8-3 times larger in volume than contralaterally projecting ones in both types of @entity19 . @entity4494 cells were relatively more common in ipsilateral retinofugal projections: 21% of all @entity4494 cells were displaced versus less than 1% of all the @entity4494 cells in black @entity19 . In albinos only 13% of the @entity4494 cells in the @entity717 were displaced. The overall reduction in ipsilaterally projecting cells in albinos was reflected twice as much in displaced @entity4494 cells as in normally placed ones.
