Reese, Koneff, and Wainman 48 1 



the enlarging vacuole. Such a change in the contour of the nucleus is rare in 

 the thyroidectomy basophil. On the other hand, enlargement of the nucleus 

 and nucleolus described in the basophil after thyroidectomy are very un- 

 common for the cells affected by castration. Although pyknosis may be the 

 ultimate fate of the nucleus in both cell types, it is not so common a phenome- 

 non after castration as after thyroidectomy. 



No difficulty was encountered in detecting the vacuolation of the nucleus 

 found by Guyer and Glaus* in the basophils after thyroidectomy. These single 

 vacuoles contained a homogeneous colloidlike material reacting like mucin 

 with methyl green.* Later such vacuoles sometimes had increased in size so 

 that they filled the nucleus. The nucleoli in such cases were pushed toward the 

 nuclear membrane (pi. i, figs. 18 and 19). In the colloidal material of the 

 nuclear vacuole, round or oval colorless spaces were sometimes present, pos- 

 sibly due in part to solution of the material in reagents used in histological 

 preparation. The growth of such intranuclear vacuoles may proceed to the 

 point at which the vacuole itself is larger than the entire nucleus of a normal 

 basophil, the nuclear membrane and nucleoli still being intact. Although 

 vacuolation of the nucleus of the basophil is less common after castration 

 than after thyroidectomy, it has nevertheless been observed in certain pitui- 

 taries from rats sacrificed at long periods after castration. These vacuolar 

 changes did not differ in any essential way from those seen after thyroidec- 

 tomy (pi. 1, fig. 20). 



Vacuolation of the nucleus cannot therefore be considered to constitute a 

 reliable criterion for differentiating the two types of basophil (as suggested 

 by Guyer and Glaus*). Nevertheless there are differences in the nuclei which 

 aid in the differentiation. The increase in size of the nucleus after thyroidec- 

 tomy is more marked than after castration. The pressure of the castration-cell 

 vacuoles often causes an elongation of the nucleus which is highly character- 

 istic. Finally, the marked enlargement of the nucleoli seen after thyroidectomy 

 is not present after castration. 



In discussing differences or similarities of castration and thyroidectomy 

 basophils one should always bear in mind that "castrationlike" or "thyroidec- 

 tomylike" basophils may occasionally be found in other types of hypophyses, 

 including normal ones. The authors do not consider, however, that cells 

 identical with those of castration occiu~ in significant numbers after removal 

 of the thyroid. The crux of the entire problem is whether any competent 

 observer can distinguish the pituitary of a thyroidectomized animal from one 

 which has been castrated if the decision is based only upon changes in the 

 basophils. Using the criteria described in this paper it is considered that one 

 should not encounter difficulty in distinguishing the two types of pituitaries 

 regardless of the postoperative period. 



* Unpublished data of A. KonefT show the effecti\eness of methyl green in staining mucoid 

 substances. 



