Occurrence of Periodic Acid–Schiff Positive Material in the Pituitary of the Parrot Fish, Pseudoscarus guacamaia

Abstract

DURING the course of investigations into the histochemistry of fish pituitaries, the distribution of periodic acid–Schiff positive material¹ was noted in the parrot fish, Pseudoscarus guacamaia. Whereas in mammalian pituitaries periodic acid–Schiff positive material is associated only with basophils (aniline-blue positive after Heidenhain's ‘Azan’ procedure), namely, the gonadotrophs and thryotrophs², in Pseudoscarus the mid-glandular region of the adenohypophysis has two types of acidophils, one of which is strongly and uniformly periodic acid–Schiff positive and the other negative. This large polygonaly shaped periodic acid–Schiff positive acidophil of Pseudoscarus stains a deep orange after the Gomori aldehyde–fuchsin orange G method for the demonstration of neurosecretory material and is carminophilic after treatment with Heidenhain's ‘Azan’ stain. In addition to this type of cell, two types of basophils are present in the mid-glandular region which are periodic acid–Schiff positive as in mammals and other teleost fish. Furthermore, although some of the periodic acid–Schiff positive basophils stained selectively after aldehyde–fuchsin as in other teleosts³, the periodic acid–Schiff positive acidophil gave a negative aldehyde–fuchsin reaction. It would appear, then, that in this fish, unlike mammals, a carbohydrate-containing hormone is possibly produced by cells which are ‘acidophilic’ after application of the conventional staining procedures.