Growth and differentiation of the secondary palate in a teleostean fish, Oncorhynchus kisutch

Abstract

AbstractA study was undertaken to examine the growth and differentiation of secondary palate in a teleostean fish, Oncorhynchus kisutch. The rate, pattern, and time of synthesis of various macromolecules, which play a crucial role during palate development in higher vertebrates were examined in the developing palate of fish. A spurt in DNA synthesis during midmorphogenesis of fish palate appeared to be related to temporal regulation of palate development. RNA synthesis was high during the time of primordial appearance and increased again from day 4 post hatching (PH) to correspond with differentiation of palate. Protein synthesis remained low initially but its trend paralleled that of RNA synthesis after day 4 PH. Glycosaminoglycan synthesis increased initially with the cartilaginous growth and then with the appearance of mucous cells. An increase in collagen synthesis corresponded with the thickening of collagen layer in the basement membrance. Cyclic AMP activity increased initially prior to the increase in DNA synthesis and subsequently remained high indicating its involvement in both growth and differentiation of fish palate. These profiles of synthesis of various macromolecules in teleostean fish differ considerably from that seen in higher vertebrates. On the basis of comparative analysis, it was suggested that the timing of mesenchymal differentiation may be one of the features in determining the characteristics of palate development in different classes of vertebrates. © 1995 Wiley‐Liss, Inc.