Quarterly Journal of Microscopical Science, Vol s3-89, 129-137, Copyright © 1948 by Company of Biologists

The Pituitary in Normal and Parasitized Roach Leuciscus Rutilus Flem.)

¹ Department of Zoology, University of Leeds

1. A short description of the glandular component of the roach pituitary is given, from the point of view of the various cell types.

2. The seasonal variations are described in the basiphils of the middle glandular region (transitional lobe), the only cell type in this fish whose variations are sufficiently regular to be reliable, and a correspondence between these changes and the sex cycle is pointed out.

3. In roach parasitized by the plerocercoid of the tapeworm Ligula these basiphils are markedly reduced in size and granulation, whilst other cell types are not affected, and the gonads are also in a condition with all the later maturation stages missing.

4. The facts presented and a discussion of other work lead to the suggestions that it is these later stages of maturation which are under pituitary control in fish as in higher types, that the middle region basiphils are the principal cell type involved, and that these basiphils are comparable to the histologically similar basiphils of the distal lobe of later vertebrates.