486 CHARLES R. STOCKARD AND E. M. VICARI 



are in the gland from his sister. The unusual conditon 

 shown is again an accumulation of bluish staining cells along 

 the outer peripheral border. These cells form irregular 

 masses without the cord-like pattern typical of the principal 

 cells. They are also somewhat larger than the principal cells, 

 and their bluish staining cytoplasm gives a slightly granular 

 appearance. At present there is no clue as to the significance 

 of these basophilic cell masses in the hybrid parathyroids. 



Figure 3 (pi. 92) illustrates a section of a parathyroid 

 gland from F 2 Boston terrier-dachshund 620 $ , shown from 

 life in plates 39 (fig. 5) and 40 (tig. 1) (pp. 236 and 238). This 

 animal was dachshund in type in all respects except that the 

 lower jaw was of definite Boston terrier proportions and fell 

 far short of proper association and dental occlusion with the 

 upper jaw. A photomicrograph of a section from the thyroid 

 of this animal, which was of typically dachshund pattern, is 

 shown in plate 85 (fig. 4). This animal was killed when about 

 6 years old and the parathyroid gland shows a somewhat 

 excessive amount of connective tissue. The principal cells 

 show the typical double row cord-like arrangement, with 

 frequent indications of a peculiar tendency to become sepa- 

 rated at places giving the appearance of a single circle of 

 cells enclosing small follicles. The tiny lumen of the ap- 

 parent follicles may contain a drop of coagulum, and the 

 wall consists of a single layer of parathyroid principal cell 

 epithelium. A number of these small follicular-like arrange- 

 ments may be seen in the left and the upper central regions 

 of the photomicrograph. 



The arrangement of principal cells in the double row cord- 

 like pattern in the dog parathyroid might be mistaken for a 

 potential tubular formation, but this arrangement is more 



PLATE 92 



EXPLANATION OF FIGURES 



Boston terrier-dachshund cross. Parathyroid histological pattern in second 

 generation and backcross Boston terrier hybrids. 



1 F 2 779 J 1 . 3 F, 620 <?. 



2 Backcross Boston terrier 524 £. 4 Backcross Boston terrier 525$. 



