論文の公開元へLectin histochemistry of posterior lingual glands of developing rats
概要
Title
Lectin histochemistry of posterior lingual
glands of developing rats
Author(s)
Harada, Kazuma; Miki, Koji; Tanaka, Susumu et
al.
Citation
Scientific Reports. 2023, 13, p. 10365
Version Type VoR
URL
rights
https://hdl.handle.net/11094/92554
This article is licensed under a Creative
Commons Attribution 4.0 International License.
Note
Osaka University Knowledge Archive : OUKA
https://ir.library.osaka-u.ac.jp/
Osaka University
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OPEN
Lectin histochemistry of posterior
lingual glands of developing rats
Kazuma Harada 1*, Koji Miki 2, Susumu Tanaka 1, Mikihiko Kogo 1 & Satoshi Wakisaka 3
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.
The oral cavity is part of the digestive system whose main function is to aid food intake. The salivary glands
produce and secrete saliva, which keeps the oral cavity moist. Lingual gland’s saliva is an important growth
factor for taste receptor c ells1. The tongue has two minor salivary glands, the anterior lingual and post l ingual2.
The anterior lingual gland, Blandin-Nühn’s gland, is a mixed gland located on the inferior surface of the tongue
apex2,3. In humans, Weber’s glands open onto the tonsils of the t ongue2,4,5, whereas in rats, Weber’s glands open
onto the dorsal epithelium at the back of the tongue, and are involved in food mass formation and swallowing2,5.
Weber’s glands are muciparous; however, the presence of serous cells has been suggested in humans and r ats2,6.
The von Ebner’s glands, which open at the base of the sulcus of the circumvallate papilla and papillae foliate, are
serous2,7,8 and secrete saliva and wash out the taste pits of taste buds in the papillary sulcus epithelium, thereby
renewing and maintaining taste receptor f unction6,9–12. They also produce tongue lipase, which hydrolyzes triacylglycerols in the acidic gastric lumen and aids the first step in dietary fat digestion2,13. In rats, the development
of the minor salivary glands occurs in the late embryonic p
eriod5, whereas the development of major salivary
glands begins in the parotid gland on embryonic day 1 45,14,15, in the submandibular gland on embryonic day
1316, and in the sublingual gland approximately on embryonic day 1817.
The posterior lingual glands are believed to be involved in the renewal of taste receptors through salivation
and washing of the taste pits of the taste buds with saliva. Lectins are often used as markers for epithelial and
mesenchymal cells to identify specific cell populations because of their ability to bind specifically to glycohydrate
epitopes on the cell membrane. By searching for the binding mode of lectins, the localization of glycoconjugates
in different tissues and the characteristics of cellular glycans in each tissue can be elucidated. Lectin histochemical studies have been reported on the distribution of lectins in various species. In summary, the previous reports
indicate that serous cells of salivary glands show binding to Ulex europeus agglutinin-I (UEAI), Soybean Glycine
maximus agglutinin (SBA), Peanut (Arachis hypogaea) agglutinin (PNA) and Wheat germ (Triticum vulgaris)
agglutinin (WGA), while mucous cells tend to show binding to Ricinus communis agglutinin (RCA) and Horse
gram (Dolichos biflorus) agglutinin (DBA)18–31. From the 21 lectins used in our laboratory and potentially binding to salivary glands, we found that SBA, PNA, and WGA bind to serous cells and DBA binds to mucous cells
in adult rats.
However, although the localization and site differences of these lectin-binding patterns have been clarified, the development of the rat posterior lingual glands and changes in lectin-binding patterns have not been
clarified. In this study, we examined the development of the rat posterior lingual glands and lectin-binding
patterns using SBA, PNA, WGA, and DBA as indices, with the aim of clarifying the relationship between the
1
The First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University,
Suita, Japan. 2Department of Periodonology, Graduate School of Dentistry, Osaka University, Suita,
Japan. 3Department of Anatomy and Cell Biology, Graduate School of Dentistry, Osaka University, Suita,
Japan. *email: harada.kazuma.dent@osaka-u.ac.jp
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development of the posterior lingual gland and the renewal of taste reception among its functions. The following
results were obtained. Weber’s glands and von Ebner glands were fully developed by postnatal day 21. Mucous
cells of the Weber’s glands were shown to bind DBA in adult rats, and SBA, WGA, PNA and DBA in the early
developmental stage. Serous cells of von Ebner’s glands were shown to bind SBA, WGA, and PNA in adult rats,
and DBA bound to the cellular membrane during early development but disappeared during development.
Matured taste buds were found on the circumvallate papilla on postnatal day 1. The present findings indicate that
the maturation of posterior lingual glands is closely associated with changes in food habit, and that the Weber’s
gland functions as a serous gland in the early postnatal stage, while the von Ebner’s gland is not yet mature. The
lectin-binding properties suggest the presence of Galβ (1,3) > Galβ(1,4) > Gal, αGalNAc > αGal > βGalNAc, and
NeuAc > (GalNAc)2–3>>>GlcNAc sugar residues in serous cells and GalNAcα(1,3) sugar residues in mucous cells
(Table 1). The results obtained provide data for the functional characterization of the rat posterior lingual gland.
Results
Hematoxylin and Eosin (H&E) staining. In adult rats, von Ebner’s glands were found to be located
just below the circumvallate papilla, separated on both sides by the lingual septum, clumped within the muscularis, and with the opening at the base of the circumvallate papilla sulcus (Fig. 1a). The Weber’s glands were
located laterally and posteriorly to the von Ebner’s glands, opening directly onto the dorsal surface of the tongue
(Fig. 1a). On embryonic day 18, the sulcus epithelium of the circumvallate papilla had not yet been inserted
into the mesenchyme. Serial sections showed clusters of epithelial cells in the lateral portion of the posterior
tongue (Fig. 1b) which were continuous with the surface layer of the tongue epithelium. On embryonic day 20,
we observed an infiltration of the sulcus epithelium of the circumvallate papilla into the mesenchyme, with no
evident formation of the von Ebner’s glands. The Weber’s glands were also found in the mesenchyme in high
number (Fig. 1c) with numerous clusters of epithelial cells present in the mesenchyme at 1 day of age (Fig. 1d),
and their number and size increased further at 3 days of age (Fig. 1e). Thereafter, the cell population of epithelial
Abbreviation
Lectin
Oligosaccharide specificity
PNA
Peanut (Arachis hypogaea) agglutinin
Galβ (1,3) > Galβ(1,4) > Gal
SBA
Soybean (Glycine maximus) agglutinin
αGalNAc > αGal > βGalNAc
WGA
Wheat germ (Triticum vulgaris) agglutinin
NeuAc > (GalNAc)2–3>>>GlcNAc
DBA
Horse gram (Dolichos biflorus) agglutinin
GalNAcα(1,3)
Table 1. Four lectins used in this study and their binding Specificity. The four lectins used in this study
for serous and mucus cells, their origins, abbreviations, and binding specificities are listed in table.
Decreased specificity is represented by one or more greater symbols. Abbreviations: Gal, galactose; GalNAc,
N-acetylgalactosamine; NeuAc, sialic acid; GlcNAc, N-acetylglucosamine.
Figure 1. Hematoxylin and Eosin staining of a rat lingual frontal section containing a circumvallate papilla.
Cross-sections of the rat tongue including the circumvallate papilla at postnatal day 56 (a), embryonic day 18
(b), embryonic day 20 (c), postnatal day 1 (d), postnatal day 3 (e), and postnatal day 28 (f). Scale is 200 µm. E:
embryonic, P: postnatal.
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cells in the mesenchyme increased over time, and both the Weber’s and von Ebner’s glands were fully developed
by 28 days of age (Fig. 1f).
The clusters of epithelial cells observed at 18 days of age were formed by cells with darker cytoplasm (Fig. 2a).
On embryonic day 20, the number of cells forming these cell masses increased, and the cytoplasm of these cells
were similarly dark (Fig. 2b). No apparent formation of terminal cells of the serous glands at the tip of the sulcus
epithelium of the circumvallate papilla, which were plunging into the mesenchyme on embryonic day 18 was
observed (Fig. 2c). ...
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