OOPHORECTOMY AND THE THYROID 39 



therefore stains blue with haematoxylin instead of pink changes in 

 with eosin ; whereas the normal thyroid colloid is, of j^er^phor- 

 course, acidophil and stains with eosin. ectomymost 



marked in 



Before attempting any explanation of the changes in rodents. 

 the thyroid after oophorectomy, we must not forget that 

 this organ in the pregnant rabbit shows a relatively 

 great increase in the amount of colloid, but it is then 

 eosinophil in character. This is not the place to 

 discuss the significance of the normal colloid collections 

 in the vesicles, as opposed to the absence of colloid seen 

 in conditions associated with excessive function. There 

 can, however, be little doubt that the normal thyroid 

 of the non-pregnant adult rabbit is not a very active 

 structure, because removal causes little or no disturb- 

 ance, an observation I have myself made on many 

 occasions. On the other hand, in pregnancy, when, as 

 is well known, increased thyroid activity occurs, we 

 find that the colloid content is increased to a considerable 

 extent in these animals, as already stated. 



It may, then, safely be asserted that there is a con- Comparison 

 siderable increase in the functional activity of the thyroid, colloidal 



so far as colloid production is concerned, in rodents after 

 oophorectomy. Why the colloid should be basophil and the 

 instead of eosinophil we can only conjecture. The ques- pl 

 tion of an artefact has been carefully considered, but 

 this explanation must be rejected for many reasons, into 

 which we need not enter here. We are, however, assisted 

 in our attempt to arrive at a conclusion by observations 

 made on the pituitary body, to some of which fuller refer- 

 rence will be made later. The normal colloidal secretion of 

 the anterior lobe and pars intermedia of the pituitary is 

 basophil, but under conditions of increased activity it 

 may be eosinophil. Further, as with the thyroid, in a 

 condition of greater hypophysial activity no * colloid' 

 is formed, but the secretion is abstracted directly from 

 the eosinophil cells. In the state of the greatest 

 activity of all the secretion is directly abstracted by the 

 blood or lymph from faintly staining basophil cells 

 the so-called ' chromophobe ' cells. There is, in fact, 



