DEVELOPMENT OF THE ENAMEL 127 



According to Rose (21), the formation of the cells of the 

 stellate reticulum commences in the centre of the enamel 

 organ. The cells of the rete mucosum of the oral epithelium, 

 closely packed under the enamel epithelium, increase in 

 size in this situation, the nuclei becoming larger and separat- 

 ing as the cells grow larger. He says : ' Between these cells 

 a clear protoplasmic fluid is secreted, causing the appearance 

 of small intercellular spaces. These spaces increase and 

 press against the neighbouring cells to such an extent that 

 the cells are finally connected with one another only by 

 means of narrow protoplasmic bridges.' He considers that 

 they * form a wide-mouthed canal system, containing a thin 

 fluid protoplasm, apparently highly suitable for a rapid 

 circulation of nutritive fluids '. 



Messrs. Underwood and Wellings (28 b) consider that ' the 

 cells (where no alcohol has been used) are round or oval, 

 with round or oval nuclei, the latter occupying most of the 

 cell. The processes which connect these cells with their 

 neighbours are wavy and not straight, and the cell envelope 

 is not drawn out where the processes are given off.' They 

 consider that the stellate appearance is artificially produced. 

 As shown, however, in fig. 74, the cells themselves are mostly 

 stellate rather than round or oval, and in some there is 

 a considerable area of cell substance around the nuclei, and 

 one would be inclined to consider that the stellate appear- 

 ance is decidedly an indication of real structure and not 

 artificially produced, although the distortion so commonly 

 apparent in preparations and in published drawings and 

 photographs might suggest this. 



With regard to the functions of the stellate reticulum, there 

 is also very considerable difference of opinion. C. S. Tomes 

 says it has been supposed to have no more important 

 function than to fill up the space subsequently taken up by 

 the growing tooth, and quotes Dr. Paul in support of 

 this view. 



As Rose points out, in the rapidly forming and speedily 

 worn out teeth of lower vertebrata there is no stellate 

 reticulum, the enamel organ being of very simple structure ; 

 but in higher animals this tissue is present, the teeth are 

 developed more slowly, and as the epithelial enamel organ 



