128 MICROSCOPIC ANATOMY OP THE TEETH 



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contains no blood-vessels, nutrition must take place by 

 osmosis, and a special arrangement is necessary to carry 

 nutriment to the growing epithelial cells. He states also 

 that the development of the stellate reticulum is intimately 

 associated with the deposition of a thick enamel cap in the 

 higher vertebrata. 



It certainly seems more reasonable to suppose that a tissue 

 consisting of such fully developed cells should take part in 

 the process of calcification by acting as a storehouse of 

 material and serving as a channel for the conveyance of 

 substances to the more active cells, than that its function 

 should be merely a mechanical one. 



C. S. Tomes is inclined to look upon the stellate reticulum 

 as a tissue which has undergone colloid degeneration, such 

 as is seen in epithelial tumours. This view was supported 

 by Eve in a paper read before the Odontological Society of 

 Great Britain in 1885 (9). In this condition the cells often 

 become enlarged and the nuclei pressed against the cell 

 wall ; but this last appearance does not occur in satisfactory 

 preparations of the enamel organ, although it may possibly 

 be seen in shrunken preparations or in later stages of develop- 

 ment, when the stellate reticulum is disappearing and 

 degenerating, and Rose's view of its functions would appear 

 much more consistent with those of a vital, developing 

 tissue. 



The Stratum Intermedium (fig. 75, s). The cells of this 

 layer communicate by their processes with those of the 

 stellate reticulum. Their nuclei are somewhat smaller than 

 those of the cells of the stellate reticulum, and when cal- 

 cification has commenced the cells and their nuclei are 

 generally seen to be slightly elongated in a direction parallel 

 with the surface of the internal epithelium, but many cells 

 retain a rounded or polygonal form. 



Before the commencement of calcification, many cells of 

 the stratum intermedium are seen lying close to and often 

 between the distal ends of the ameloblasts ; but after calcifica- 

 tion has commenced they are completely shut off from these 

 cells by a membrane, the outer ameloblastic membrane of 

 Williams. 



After the stellate reticulum has disappeared in the later 



