Postnatal morphological and lectin histochemical observation of the submucosal glands of rat nasopharynx

The development of submucosal glands of rat nasopharynx was studied with respect to their morphological maturation and glycoprotein alterations during the postnatal period. This study examined the histological morphology with hematoxylin-eosin and the binding pattern of lectins, soybean agglutinin (SBA), Dolichos biflorus agglutinin (DBA), Vicia villosa agglutinin (VVA), Ulex europaeus agglutinin-I (UEA-I), peanut agglutinin (PNA), wheat germ agglutinin (WGA), and succinylated WGA (sucWGA) on frozen sections from newborn into adulthood. At birth, nasopharyngeal glands consisted of rudimentary secretory units which by postnatal day 3 (PN3) showed the characteristic features of salivary glands comprised of mixed mucous and serous cells. With maturation, serous cells increased in number and were arranged in clusters. Lectin reactivity at birth was detected at the acinar cell basal membranes for DBA, SBA, VVA, UEA-1 and PNA. At PN3, lectins labeled the apical cytoplasm and basolateral membranes of mucous cells and progressively with maturation, extended from the apical to basal portions of the cytoplasm with variable reactivity of VVA, PNA and sucWGA. Serous cells were labeled by UEA-1 starting from PN10 and also by PNA in adults. Ducts showed variable lectin reaction on the luminal membrane with strong reactivity of DBA and UEA-1 at PN21. Taken together, lectin histochemistry indicated the transitional occurrence of glycoproteins depending on the stage of maturation of the glands. Moreover, these results emphasize the difference in the morphology and lectin histochemistry between the nasopharyngeal and palatine glands.