Evidence is given for the existence of two main types of cyanophil cell in the median zone of the glandular lobe (adenohypophysis) of the minnow, distinguishable by their distribution and by their cytological characteristics. Both types are positive to the periodic acid Schiff (PAS) technique, but one (type 2 of this account) also gives a positive response to the aldehyde-fuchsin (AF) technique of Gomori, as used by Halmi and by Purves and Griesbach in studies of the mammalian pituitary. In fish which have been immersed in thiouracil solution the type 2 cells show degranulation and vacuolation, and their characteristic positive AF response is very greatly weakened or lost. For these reasons the type 2 cells are believed to be responsible for the secretion of thyrotrophin, and appear to be very closely comparable with the thyrotroph cells of the pituitary of the rat.
- Copyright © 1955 by the Company of Biologists Ltd.