Ultrastructural studies on Purkinje cells of the frog tadpole cerebellum.

The Purkinje cells of the premetamorphic frog tadpole cerebellum were studied with the transmission electron microscope. At this stage of histogenesis, when the external granular layer is yet to be formed, their maturational state varied greatly from randomly oriented cells with a thin rim of cytoplasm to well-formed cells with an abundance of organelle-rich cytoplasm and well-developed dendrites. The well-developed cells were seen in the apical (marginal) region of the cerebellar plate and the poorly developed cells in the basal region. Climbing fibers and other unidentified processes formed synapses on the well-developed Purkinje cell somata and somatic dendrites and on the spines and smooth surfaces of the primary dendrites.