Changes in the surface fine structure of ependyma of the rat third ventricle following operative leakage of cerebrospinal fluid.

The role of the ventricular ependyma in the elaboration of cerebrospinal fluid under resting conditions is well documented. In an attempt to elucidate its response to cerebrospinal fluid leakage, male young adult Wistar rats were subjected to lumbar spinal transection under intraperitoneal Nembutal anaesthesia. Control animals received a sham operation, involving opening up the cerebrospinal fluid space and its closure. A scanning electron microscopical study of the third ventricular ependyma on the seventh postoperative day revealed pronounced surface modifications in the experimental animal which included (i) bulbous dilatations in the ciliary shafts with frequent apical blebbing, and an overall turgid appearance of most cilia; (ii) a profusion of tall and stout microvilli in the non-ciliated zones; (iii) an increase in the size and number of blebs; and (iv) a greater number of supraependymal cells especially on the ventricular floor. The significance of these changes is discussed in the light of available studies. The results, considered collectively, seem to reflect an augmented activity of the ventricular ependyma as a compensatory measure to counteract the effects of cerebrospinal fluid leakage caused by surgical trauma. Such activity may be both absorptive and secretory in nature.