Nutritional Secondary Hyperparathyroidism in the Horse

18 'I'hc Anatomy of the Parathyroid Glands in the Horse
defined than that of any other cell (Figs. 8, 9, and 10). In intermediate
stages the basophilic cytoplasmic structures coalesced to form small
spherical bodies, crescentshaped flakes, or more irregular formations.
The spherical bodies could occur at a juxtanuclear position, but when
they were multiple, as was often the case, they could also occur in the
extreme peripheiy of the cell. The flakes occurred irregularly in the
cytoplasm. The more complete the development of the waterclear
cells was, the more peripheral was their location. The well-defined
membrane of the water-clear cells was due to the presence of such
coalesced flakes glued like tapestry to the cell membrane. The cyto-
plasm contained no stainable fat. The nucleus was smaller than it was
in the light chief cell and the cytoplasm to nucleus ratio, therefore,
increased (Table 11).
Pale oxyphil cells were rare. They were present in horses 10 years
of age and older. The incidence did not increase with increasing age;
they were always rare. Usually they occurred singly, but sometimes
they were in pairs (Fig. 9) or, very rarely, in islands of three or more
cells. The cytoplasm of these huge cells (Table 11) was slightly granular
and intensely pink. The nucleus was circular and deeply basophilic,
and the nucleoli were sharply demarcated. The pale oxyphil cells did
not contain stainable fat.
At this point it may be worth while to describe an artifact that
occurred in a few cases. Fig. 10 shows a well-circumscribed area in
which the cytoplasm was finely granular and intensely pink. Under
low or medium-high magnification the cells were at first confused with
pale oxyphil cells. Under oil immersion (Fig. 10, insert) it could be
seen, however, that the cell borders were disrupted and that the well-
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