442 CHARLES R. STOCKARD AND E. M. VICAKI 



This animal was in general a dachshund-like dog. The head, 

 as the photographs show, was almost fully dachshund: the 

 only typically Boston terrier feature is the marked reduction 

 in mandibular growth giving an abnormally short lower jaw. 

 Corresponding with the head and body type, the histologic 

 structure of the thyroid is of the long muzzled dachshund 

 pattern as found in the survey of pure breed thyroids. This 

 gland is in a somewhat inactive condition, with rather brittle 

 colloid. 



Highly contrasted with the foregoing thyroid is the F2 

 section in figure 5. This thyroid is from a 2 year old dwarf 

 male, 77!), which exhibited a considerable degree of short- 

 wide head resembling the Boston terrier stock. The dog from 

 life is shown as figure 4 in plate 30 (p. 129). The histologic 

 picture of the thyroid of this animal shows only small ir- 

 regular follicles with extremely high columnar epithelium 

 and numerous droplets, an almost typical illustration of 

 pathologic hyperthyroidism. Just above the center of the 

 photomicrograph are several large nests of lightly stained 

 parafollicular cells, and single cells of this type are richly 

 scattered throughout the section, a feature very characteristic 

 of the Boston terrier thyroid. This F 2 thyroid resembles 

 much more exactly that of the Boston terrier in plate 82 (fig. 

 2) than it does the less active thyroid in plate 85 (fig. 2). 



Photomicrographs from sections of four other thyroid 

 glands from F 2 Boston terrier-dachshund hybrids are shown 

 in plate 86 (figs. 1 and 2) and plate 89 (figs. 3 and 4) for 

 comparison with those in plate 85. Figure 3 in plate 89 is 

 histologically about the same as the thyroid of the dachshund; 



PLATE 85 



EXPLANATION OF FIGURES 



Boston terrier-dachshund cross. Photomicrographs showing the inheritance of 

 thyroid histological patterns in first and second generation hybrids. 



