CILIARY FINE-STRUCTURE OF EPITHELIUM OF THE RENAL TUBULE IN URODELE, TRITURUS ENSICAUDA, WITH SPECIAL REFERENCE TO THE SO-CALLED 'DENSE GRANULES' IN THE BASAL BODY.

Abstract

The ciliary fine-structure of the neck segment of the nephron in Triturus ensicauda was studied by electron-microscope.The structure of the cilium is basically similar to various organisms, but there are considerable variations in the ciliary apparatus. The distal part of the basal body curves and becomes narrower and finally is closed. There is no basal plate at the level of the upper limit of the basal body, and the basal part of the central fibrils of the cilium ends in the central cavity of the shaft portion of the basal body without adhering to any concrete structure. From the wall of the shaft portion, the knoblike process projects towards nearly the same direction of a movement of the cilia. It also shows the same density as that of the wall of the basal body. The lumens of the shaft portions with moderate numbers of basal bodies are filled with a considerable numbers of dense granules, each of which is about 200A in diameter and more or less polygonal. These granules are aligned in rows along the long axis of the basal body and nearly in contact with the wall of the basal body. One peripheral fibril probably has a single row of dense granules, so nine rows of granules are arranged in the lumen of the basal body. From the tail part of each basal body two rootlet fibers arise; each of which extends at random towards the apical cytoplasm of the epithelial cell and has crossbanding with definite period.