Histochemical study of magellanic penguin (Spheniscus magellanicus) minor salivary glands during postnatal growth

The histological and histochemical features of the minor salivary glands du ring postnatal development have been generally associated with the type of food ingested. However, recent studies support the fact that these salivary glands develop independently of the diet; in fact, minor salivary glands h ave similar morphological and histochemical characteristics in adult indivi duals of species with different diet regimens. Thus, the aim of this study was to characterize the developmental morphology of the penguin minor saliv ary glands and to contrast them with minor salivary glands of other species . The tongue, palatine, and mouth cavity (bottom) minor salivary glands of ne wborn, 1- to 20-day-old, and adult magellanic penguins were studied with he matoxylin-eosin, periodic acid-Schiff, alcian blue, toluidine blue, and lec tin histochemistry. Minor salivary glands were present at all ages, although they were only mod erately developed in animals less than 15 days old. After this age, glands were abundant in all age groups; in addition, cells from the glandular epit helium mere functionally mature and secreted mucins. Nevertheless, in newbo rn to 15-day-old penguins, mucins were located only at the apical cytoplasm of mucous cells. In all ages, mucous cells displayed periodic acid-Schiff- positive, alcianophilic, and metachromatic reactions; among mucous cells, o ther orthochromatic cells appeared interspersed. From 15 days on, histochem ical reactions became more intense until adulthood, and the cytoplasm of se cretory cells was filled with glycoproteins and sulfomucins. Moreover, lect ins bound to different oligosaccharides in mucous cells, depending on the s tage of maturation of the glands. In conclusion, penguin minor salivary glands are already present at birth, and show progressive and quantitative increases in mucous secretion during postnatal development. These changes are necessary not only for nutrient in gestion, but also for nonimmune protection of the buccal cavity. Anat Rec 2 54:298-306, 1999. (C) 1999 Wiley-Liss, Inc.