324 Kojima 



The intraglandular cleft ia sometimes broad, in other cases quite 

 narrow. Occasionally the pars anterior and the pars intermedia are in 

 direct contact, so as to leave only a chain of spaces indicating the 

 situation of the cleft. In other instances there is a wide space separating 

 the pars anterior and pars intermedia. A small amount of hyaline 

 substance may occasionally be seen within the cleft, l)ut in many cases 

 there is no such material visible. 



Effects of Thyroidectomy in Rat (fig. 2 and Plate III.). 



After total thyroidectomy (the parathyroids were reimplanted in the 

 wound, althougli I have not been able to obtain evidence that the graft took) 

 striking changes become apparent in the structure of the pituitary body 

 (fig. 2), provided the animals are kept sufficiently long after the operation.^ 

 Thus in an animal killed thirty-four days after thj'roidectomy the pars 

 anterior is less compact in structure than in tlie normal animal, and a large 

 number of vesicles are visible over the whole section. These vesicles vary 

 in size and shape. Many are full of hyaline substance which stains faintly 

 red with eosin. Others are empty. There are also a considerable number 

 of large swollen-looking cells the cytoplasm of which is open in appear- 

 ance and is stained lightly by eosin : the outline of these cells is in most 

 cases indistinct. Their cytoplasm contains numerous small vacuoles. In 

 some of these cells the cytoplasm is coloured homogeneously red by eosin, 

 the appearance being very like that of hj^aline substance. All except the 

 oxyphil cells are stained blue by Mallory (aniline blue). The hyaline 

 substance just mentioned is also stained blue by Mallory, although, as 

 already mentioned, faintly reddened by eosin in ha3matoxylin -eosin prepara- 

 tions. The ordinary oxyphil and basiphil cells are remarkably few in 

 number. The pars intermedia is relatively thickened. The above changes 

 are already visible twenty-three days after thyroidectomy, and they are 

 not removed after feeding the thyroidectomised animals for some days with 

 1 grm. of dry ox-thyroid per rat per diem (fig. 6). 



Effects of Parathyroidectomy in Rat. 



Removal of parathyroid alone does not appear to be productive of such 

 marked changes in the pituitary body as removal of thyroid. In the pituitary 

 of a rat killed thirty-five days after parathyroidectomy, the pars anterior, 

 which has a compact appearance under a low power, shows a certain number 

 of small vesicles containing hyaline substance and a large number of oxyphil 

 cells (fig. 3). These cells are for the most part slightly enlarged, and many 

 of their nuclei are rather larger than in the normal gland (5/x to 7"5yu,). 

 There are a certain number of swollen cells similar to those described after 

 thyroidectomy, but they are fewer. Their cytoplasm is spongy and finely 

 vacuolated, and stains pinkish -red in hsematoxylin-eosin preparations. 



^ The rat i.s a particularly favourable animal for such experiments because it is not, as 

 are most other animals, liable, to tetany as an early result of removal of parathyroids. 



