THE PARS BUCCAL1S OF THE HYPOPHYSIS 87 



Structurally, this atrophy is expressed by a reduction in the 

 size of the follicles and in their colloid content (figs. 33 to 36). 

 Indeed, certain cell clusters would not be recognizable as a 

 follicular remnant, save for their location, so atypical are they. 

 Other follicles exhibit the characteristic organization and may 

 even contain an insignificant amount of poorly staining colloid. 

 In no case do we see the large-sized, colloid-filled follicle of the 

 normal animal. The component cells of the follicles appear also 

 to have suffered from the hypophysial deprivation. Their 

 cytoplasmic content is very noticeably diminished. This reduc- 

 tion in the size of the component follicles, together with an 

 apparent disappearance of some of them, results in a loose 

 organization of the gland, the majority of the follicles being 

 separated by wide intervals. Had these interfollicular spaces 

 been excluded in the models, an even greater discrepancy be- 

 tween the size of the thyroids of the albino as compared to the 

 normal would have been shown. 



Although not evident in specimens of 10 mm. total length 

 (eighteen days after the operative stage), by the time larvae 

 have reached a length of 17 to 18 mm. (twenty-nine days after 

 the operative stage) the thyroid of the albinos is slightly but 

 invariably smaller than that of the controls. This discrepancy 

 progressively increases and is strikingly expressed in a 24-mm. 

 (thirty-nine days after the operative stage) albino as shown in 

 table 7. The pronounced atrophy of this gland in the albino 

 is not due, then, to a regressive process in the normal gland; 

 it is a phenomenon of retarded and atypical development. 



It will be recalled that the 'partial' albinos, because of the 

 position assumed by the atypical epithelial fragment of the 

 hypophysis, were grouped into three classes: 1) those in which 

 there was no contact between the true neural lobe and the epi- 

 thelial fragment; 2) those in which there was a definite but 

 slight juxtaposition between these two components; and, 3) 

 those in which the epithelial fragment though diminished in size 

 nevertheless displayed its usual division into glandular and inter- 

 mediate lobes, which in turn displayed the usual relation with 

 the infundibular derivatives. Curiously, the thyroid glands of 



