The Golgi Apparatus of the Ameloblast of the Rat at the Stage of Enamel Matrix Formation

In adult rats, the continuous growth of the incisor tooth is associated with continuous mitotic division of the immature ameloblasts located at the root tip. As some of these cells migrate distally, they mature and eventually secrete enamel matrix, at which time they may be referred to as secretory ameloblasts. When this stage is reached, the Golgi apparatus of the ameloblasts acquires a rather unusual shape. Since this shape has not been described by previous authors, a brief description will be given. The secretory ameloblasts from the upper and lower incisors of adult white rats were investigated. For light microscopy, the osmium tetroxidezinc iodide method of Maillet (1) as well as the silver technique of Elftman (2), both of which have been reported to stain the Golgi apparatus, were employed. Pieces of enamel organ were also fixed in buffered osmium tetroxide solution, block-stained with hematoxylin by Schultze's method (Romeis, 3) and embedded in Epon (Luft, 4). Sections of these blocks were cut for light microscopy at ~ to 2 ~. For electron microscopy, sections were cut at 500 A and stained with lead hydroxide (Karnovsky, 5).