Development of a slice preparation of the mammalian retina

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The vertebrate retina is a thin nervous tissue with a thickness of approximately 200 mum consisting of 5 types of neurons. To understand the mechanism of visual information processing in the retina, it is important to know the characters of membrane ionic channels, transmitter receptors and the input-output relation in all types of neurons composing the retina. Patch clamp studies on dissociated and cultured retinal neurons provided a vast amount of knowledge on the elementary processes. However, the isolated cell preparation is not suitable for the study of the dynamics of the synapse. The classical intracellular recording technique is used to record light-induced voltage responses of each neuron, but the obtained data is insufficient for quantitative analysis. The slice preparation has a powerful advantage in that the neural circuit is preserved and the cells composing a synapse are accessible under the direct visual control. The present study was made to develop a technique with which slice preparations can be made of the mammalian retina and the cells in the slice preparation can be recorded by a patch clamp technique.With collaboration of the machine shop of our University, we designed and constructed a slicer suitable for the retina. The isolated retina is mounted on a Millipore filter, with the receptor side up, and the retina-filter paper is sectioned vertically by a razor blade attached to the arm of the slicer. Once sectioned, the preparation is advanced by a micrometer for 100-200mum. By repeating this process, we obtained retinal slices of the thickness we wanted. The slice is immediately moved to a neighboring recording chamber that can be mounted on the stage of the microscope for recording and examining the effects of various pharmacological agents by bath application. We began experiments on goldfish retina, and are now studying the retina from the mouse.