Comparative observations on the pineal body of some Australian Parrots

Abstract

The pineal bodies of 19 species from 5 families and 13 genera of Australian parrots were examined. Histological studies revealed differences in shape and structure of this organ among various groups. Three morphological types are recognized: (1) a wedgeshaped form typical of the great majority of birds; (2) a more elongated tubular form, found in some birds and intermediate between the first and third groups; (3) an extremely long tubular form. The modifications and development of the pineal body in other birds and in other vertebrate classes are discussed in relation to the conditions found in parrots. Some possible evolutionary trends for the pineal in the Order Psittaciformes are suggested.