518 CHARLES R. STOCKARD AND E. M. VICARI 



the cords of cells lead directly into this large sinusoid. A 

 faintly staining mass of bluish cells is seen at the top of 

 the section above the sinusoid and immediately to the right 

 of the mid-line. There is not the profuse arrangement of the 

 bluish stained cells as was noted around the sinusoids in 

 figure 1. The differences between these two parathyroid 

 sections from the bassethound and the bulldog are as pro- 

 nounced as the differences between their thyroids. Yet the 

 parathyroid differences may not be equally expressed in a 

 comparison of all parathyroid bodies of the two individuals; 

 neither are they so consistent as the differences in histologic 

 patterns of the two thyroid glands. 



The parathyroid glands from two Fj hybrids between the 

 bassethound and bulldog are illustrated in figures 3 and 4. 

 The size and general cord-like arrangements of the principal 

 cells approach nearer the parathyroid picture of the basset- 

 hound than of the bulldog. In figure 3, from 603 9 , a 6 year 

 old brood-bitch, bluish cells are present in the upper left 

 corner, and several large sinusoids lie among the cords of 

 principal cells. 



Figure 4 shows a very large parathyroid cyst lined by 

 ciliated epithelium and filled with greyish granular cystic 

 fluid. This might be interpreted as a definite persistence of 

 embryonic branchial epithelium due to abnormal outgrowth 

 during parathyroid development. In confirmation of this, the 

 entire gland is lobulated, and loose loops of cell strings show 

 failure to form the usually compact cord arrangements. Both 

 large and small parathyroid cysts are not infrequent in these 

 hybrids. 



Figures 5 and 6 illustrate sections of the parathyroid glands 

 from two F 2 brothers, 13135 and 13125. Figure 5, from 

 1313 $ , shows a few clear sinusoidal spaces near the top and 

 to the right. Conspicuous dark masses of different sizes are 

 scattered throughout this section and careful examination 

 shows these to be congested masses of cells with dull blue 

 staining granular cytoplasm, a more pronounced expression 

 of the streaks and masses of dull blue cells seen in other 



