ABSTRACT
The present study intended to provide some informations about the relationship between the supraependymal structures (SES) and the periventrieular neural tissue (PVNT), and with gross dissection and scanning electron microscopy the anterior medullary velum (AMV) was observed on 20 adult rabbits. The AMV may be divided into three portions: 1. the posterior membraneous wall of the recess of the inferior colliculus; 2. the anterior roof of the fourth ventricle; and 3. the transiional portion between the two portions mentioned above. On the ependymal surface of the entire AMV. There were numerous microvilli and cilia, except for the second portion of AMV, there were also some spherical-like structures, which were 2-6?m in diameter and had lace-like processes on its surface, and supraependymal cells(SEC) which were stellate, triangular, and spindle in shape. On the cellular surface with very few SEC, the secretory granules may be seen, which were 0.1-0.3?m in diameter. The SEC often extended out 2-5 processes, and the distal parts of which expanded into a flattened shovel-like structure, which lay on or inserted into the ependymal surface. The SEC here are similar to type Ⅱ SEC seen in the third and fourth ventricles, but they may differ significantly in structures on cellular surface, e.g. the secretory granules, and in shapes of their processes. Thus, it may suggest that the SEC here may play an intermediary role between PVNT and CSF, and be another route of neurohumoral modulation.