Axo-axonic Septate Junctions in the Basket Formations of the Cat Cerebellar Cortex

In the cat cerebellar cortex, as in most higher vertebrates, the descending branches of the basket cell axon envelop the Purkinje cell body in the region of its axon hillock in a basket-like arborization (Rambn y Cajal, 1909) . This report further characterizes the basket formations of the cat and describes septate junctions between the descending branches of the basket cell axons and between some of these branches and the initial segment of the Purkinje cell axon. Since their original description in Hydra (Wood, 1959), septate junctions have been found between many different kinds of invertebrate epithelial cells (Wiener et al ., 1964 ; Locke, 1965 ; Danilova et al ., 1969; Satir and Gilula, 1970, among others) and between some vertebrate epithelial cells (Potts, 1966; Barros and Franklin, 1968 ; Rupec and Braun-Falco, 1968) although they have not been reported previously in the central nervous system. Structures resembling septate junctions have been described in the turtle retina (Lasanky, 1969) .