Localization of Ulex europaeus agglutinin-I (UEA-I) in the developing gustatory epithelium of the rat

Lectin histochemistry of posterior lingual glands of developing rats

The posterior lingual glands are classified as Weber and von Ebner glands. Glycans play an important role in salivary glands. Although the distribution of glycans can explain functional diversity and variation, there are many unknowns in the developing rat posterior lingual glands. The purpose of this study was to elucidate the relationship between the development and function of the posterior lingual gland in rats by histochemical analysis using lectins that bind to sugar residues. In adult rats, Arachis hypogaea (PNA), Glycine maximus (SBA), and Triticum vulgaris (WGA) were associated with serous cells and Dolichos biflorus (DBA) with mucous cells. In both Weber's and von Ebner's glands, all 4 lectins were bound to serous cells in early development, but as development progressed, DBA disappeared in serous cells and only the DBA remained in mucous cells. These results suggest that Galβ (1,3) > Galβ(1,4) > Gal, αGalNAc > αGal > βGalNAc, NeuAc > (GalNAc)_2-3>>>GlcNAc, and GalNAcα(1,3) are present in the early stage of development, but that GalNAcα(1,3) disappear in serous cells and only GalNAcα(1,3) are localized in mucous cells after maturation. These results indicate that Weber glands function as serous glands in the early postnatal stage when von Ebner glands have not matured.

Lectin histochemistry of palatine glands in the developing rat

This study examined 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) in the developing rat palatine glands. In adult rats, heterogeneous lectin binding patterns were revealed between the anterior and posterior portions of palatine glands, as DBA, VVA, and WGA were bound more intensely and broadly in the posterior portion. SBA, PNA, and sucWGA showed far less reactivity in the anterior than in the posterior portion. At embryonic day 18 (E18), weak labeling was observed with UEA-I and WGA at the basal membrane of terminal buds, UEA-I and PNA labeled the epithelial cord, and there was no apparent binding for SBA, DBA, VVA, and sucWGA. At E20, after acinar lumenization, all lectins were detected at the acinar cell basal membranes. After birth, all lectins detectably labeled at the mucous cell apical membranes and progressively, with maturation, extended from the apical to basal portions of the cytoplasm. Apparent serous cells were observed around postnatal day 10 (PN10) and bound UEA-I. Lectins reached peak reactivity at PN21 and the binding patterns became identical to those of adults around PN28.

Morphological evidences in circumvallate papilla and von Ebners' gland development in mice

In rodents, the circumvallate papilla (CVP), with its underlying minor salivary gland, the von Ebners' gland (VEG), is located on the dorsal surface of the posterior tongue. Detailed morphological processes to form the proper structure of CVP and VEG have not been properly elucidated. In particular, the specific localization patterns of taste buds in CVP and the branching formation of VEG have not yet been elucidated. To understand the developmental mechanisms underlying CVP and VEG formation, detailed histological observations of CVP and VEG were examined using a three-dimensional computer-aided reconstruction method with serial histological sections and pan-Cytokeratins immunostainings. In addition, to define the developmental processes in CVP and VEG formation, we examined nerve innervations and cell proliferation using microinjections of AM1-43 and immunostainings with various markers, including phosphoinositide 3-kinase, Ki-67, PGP9.5, and Ulex europaeus agglutinin 1 (UEA1). Results revealed specific morphogenesis of CVP and VEG with nerve innervations patterns, evaluated by the coincided localization patterns of AM1-43 and UEA1. Based on these morphological and immunohistochemical results, we suggest that nerve innervations and cell proliferations play important roles in the positioning of taste buds in CVP and branching morphogenesis of VEG in tongue development.

Histochemical changes and apoptosis in degenerating taste buds of the rat circumvallate papilla

The present study was designed to examine the histochemical changes and occurrence of apoptosis in taste buds of rat circumvallate papillae following bilateral transection of the glossopharyngeal nerve. Following transection of the glossopharyngeal nerve, the number of taste buds was not altered until post-operative day 3 (PO3), but decreased significantly thereafter. The number of cells within a taste bud, however, decreased significantly from PO2. In normal, uninjured animals, approximately 15.4%, 9.0%, and 7.7% of taste bud cells were labeled with antibodies for phospholipase C beta2 subunit (PLCbeta2), a marker for type II cells, neural cell adhesion molecule (NCAM), a marker for type III cells, and Jacalin, a marker for type IV cells, respectively. Following gustatory nerve injury, the ratio of cells expressing markers of type III and type IV decreased gradually from PO2, and Jacalin-labeled taste bud cells disappeared on PO3. Under normal conditions, immunoreactivity for single-strand DNA (ssDNA), a marker of apoptosis, was detected in the nuclei of PLC beta2-immunoreactive cells and cells showing no labeling for PLCbeta2, NCAM, or Jacalin. On PO1, the number of taste bud cells showing ssDNA immunoreactivity increased to double that of normal uninjured animals; these ssDNA-immunoreactive cells were also labeled with NCAM and Jacalin as well as PLCbeta2. The present results suggest that denervation of the gustatory nerve causes apoptosis in all types of taste bud cells, resulting in the rapid degeneration of taste buds.

Jacalin and peanut agglutinin (PNA) bindings in the taste bud cells of the rat: new reliable markers for type IV cells of the rat taste buds

Lectin histochemistry of Jacalin (Artocarpus integrifolia) and peanut agglutinin (PNA), specific lectins for galactosyl (beta-1, 3) N-acetylgalactosamine (galactosyl (beta-1, 3) GalNAc), was applied to the gustatory epithelium of the adult rat. In the ordinary lingual epithelium, Jacalin and PNA labeled the cell membrane from the basal to granular cell layer. They also bound membranes of rounded-cells at the basal portion of taste buds, but the number of PNA labeled cells was smaller than that of Jacalin labeled cells. There was no apparent difference in the binding patterns of Jacalin and PNA among the taste buds of the lingual papillae and those of the palatal epithelium. Occasionally, a few spindle-shaped cells were labeled with Jacalin, but not with PNA. Double labeling of Jacalin and alpha-gustducin, a specific marker for type II cells, revealed that Jacalin-labeled spindle-shaped taste cells were immunonegative for alpha-gustducin. Spindle-shaped cells expressing protein gene product 9.5 (PGP 9.5) immunoreactivity lacked Jacalin labeling. During the development of taste buds in circumvallate papillae, the binding pattern of Jacalin became almost identical from postnatal day 5. The present results indicate that rounded cells at the basal portion of the taste buds cells (type IV cells) bind to Jacalin and PNA, and these lectins are specific markers for type IV cells of the rat taste cells.