Lectin receptors in the salivary glands of the rat during postnatal ontogenesis

Distribution of lectin-binding sites in rat submandibular and sublingual salivary glands during postnatal development has been investigated. Lectin preparations include con A, lentin lectin, castor beans agglutinin, peanut, soybean and Sophora japonica agglutinins, wheat germ agglutinin and lectin from the bark of Laburnum anagyroides. The direct and indirect peroxidase techniques are used. According to the similarities of histochemical patterns, all lectins are divided into four groups. Besides the general patterns of lectin binding sites, some details are noted. Lectins of peanut and Sophora japonica possess an extremely high affinity to mast cells, con A, lens lectin, castor beans and wheat germ agglutinins--to serous demilunes cells. Laburnum lectin--to salivary ducts epithelia in adult rat salivary glands. Lentin lectin, con A and Laburnum lectin preferentially stain cells with specific granularity in granular ducts at early stages of postnatal development. Considering the character of staining, we propose for further histochemical investigations of the salivary glands lentin lectin, peanut agglutinin, wheat germ agglutinin and Laburum anagyroides lectin.     

Adenylate cyclase activity in rat submandibular gland during postnatal development

Adenylate cyclase activity was measured in homogenates of submandibular glands of 1 to 42 day old rats. During this period of time the gland reached its final stage of differentiation. Adenylate cyclase activity was higher in the glands of one day old rats than in those of 7 and 14 day old animals. Between 14 and 28 days of age the enzyme activity more than doubled and approached the level that characterized the glands of adult animals. Fluoride (10mM) stimulated the enzyme activity in all age groups but the stimulation was less in the case of one day old rats as compared to older animals. Isoproterenol (10^?4 M) stimulated adenylate cyclase by 50–60% in the gland of adult rats but had no effect on the enzyme activity in 7 to 28 day old animals. Administration of isoproterenol for 5 days to 9 day old rats increased the weight of the submandibular gland by 70 per cent. Total adenylate cyclase activity increased parallel with the weight of the gland but the specific activity of the enzyme remained unchanged. It is concluded that during the postnatal development of the submandibular gland the rapid increase in adenylate cyclase activity occurs after weaning and it coincides with an accelerated rate of functional differentiation of the acinar cells.     

Quantitative changes of the C-cell population in the rat thyroid during postnatal ontogenesis

Summary The number and distribution of C-cells in the rat thyroid gland, have been investigated during postnatal ontogenesis from birth to 120 days of age. The argyrophilic and metachromatic properties of these cells were used to identify them. In the thyroid of newborn rats the C-cells do not exhibit argyrophilia and metachromasia. These reactions appear at 10 days and can be seen at all subsequent ages. The number of C-cells shows a parallel increase with age as demonstrated by the change in the proportion of C-cellsF-cellscolloidstroma during development. A marked increase in C-cells was found at 50 days of age when the proportion of C-cells rose to 27.67% from the value of 16.78% at 30 days. At 70 days a decrease was noted (20.50%) which hardly changed until 120 days of age (22.20%). The numerical increase in C-cells occurs at the expense of the follicular epithelium and stroma.The C-cells occupy elongated islet-like region in the central part of the lobe, decreasing in number towards the periphery where no C-cells are present. The long axis of the C-cells area is parallel with the longitudinal axis of the lobe. The area of C-cells is largest at the centre of the lobe, corresponding to the territory of the peak of the Gaussian curve for the numerical distribution of C-cells.     

Lectin cytochemistry on developing rat submandibular gland primary cultures

Lectin cytochemistry was performed in vitro on primary cultures from the rat submandibular gland. For this purpose, prepubertal rats (17, 27, 33 days old) of both sexes were used. Several types of medium supplements were tested and it was found that cells survived until 15 days in presence of all medium supplements and extracellular matrix gel. The binding patterns of all FITC/TRITC-labeled lectins, with and without prior sialidase digestion and deacetylation, were analyzed in a confocal laser scanning microscope. In particular, the occurrence of C4 acetylated sialic acid linked to beta-galactose at day 27 and the presence of fucose residues at day 33 indicated that lectin probes applied to cultured cells give results similar to those obtained in intact tissues and can be used as markers of growth and differentiation.     

Lymphoid structures in the wall of the human esophagus during postnatal ontogenesis

Lymphoid aggregates in the wall of the human oesophagus have been studied in corpses of 107 persons died a sudden death and who had not any disease in the digestive organs and in the immune system (total plane preparations, slices stained with hematoxylin--eosin, azure-2-eosin and after van Gieson). The lymphoid aggregates are arranged as longitudinal chains. Their number increases from birth towards the second childhood, and then decreases towards the old age. In the upper oesophageal parts these aggregates are more numerous than in the lower ones. The lymphoid aggregates look like convexoconvex lenses. Their size is maximal during the second childhood, the longitudinal dimensions are nearly two times as great as their thickness. With time, the sizes of the formations become small. The arrangement density of the lymphoid cells in the subepithelial layer of the mucous membrane is maximal in newborns, and then it decreases up to the old age. The lymphoid aggregates are situated in the oesophageal wall, mainly, near the ducts of the oesophageal glands.     

Immunohistochemical localization of dipeptidyl aminopeptidase (DAP) IV in the rat submandibular gland during postnatal development

Summary The localization of dipeptidyl aminopeptidase (DAP) IV in the rat submandibular gland during postnatal development was studied immunohistochemically using the unlabeled antibody enzyme method. Cryostat sections of rat submandibular glands were examined in animals 1 to 50 days old. In the first postnatal week, faint immunoreaction was detected in the apical region of the cytoplasm of terminal tubules. During the second postnatal week the reaction was gradually restricted to the luminal region of terminal tubules or developing acinar cells, and its intensity increased. The most striking change of the enzyme localization was observed in 15-day-old rats. At this time, DAP IV was confined to the luminal and lateral membranes of differentiated acinar cells and to the luminal membranes of intercalated and striated duct cells. This localization pattern was similar to that of the adult animal. DAP IV activity in the gland was also measured biochemically during the postnatal development. The results were in agreement with those of the immunohistochemical study. These results suggest that the localization of DAP IV is closely related to the postnatal differentiation and proliferation of acinar cells.     

Immunohistochemical profiling of the ultimobranchial remnants in the rat postnatal thyroid gland

Ultimobranchial (UB) remnants are a constant presence in the thyroid throughout rat postnatal life; however, the difficulty in identifying the most immature forms from the surrounding thyroid tissue prompted us to search for a specific marker. With that objective, we applied a panel of antibodies reported to be specific for their human counterpart, solid cell nests (SCNs), using double immunohistochemistry and immunofluorescence. Our results demonstrated that cytokeratin 34βE12 and p63 are highly sensitive markers for the immunohistologic screening of UB‐remnants, independently of their maturity or size. Furthermore, rat UB‐follicles (UBFs) coincided with human SCNs in the immunohistochemical pattern exhibited by both antigens. In contrast, the pattern displayed for calcitonin and thyroglobulin differs considerably but confirm the hypothesis that rat UB‐cells can differentiate into both types of thyroid endocrine cells. This hypothesis agrees with recent findings that thyroid C‐cells share an endodermic origin with follicular cells in rodents. We suggest that the persistence of p63‐positive undifferentiated cells in UB‐remnants may constitute a reservoir of basal/stem cells that persist beyond embryogenesis from which, in certain unknown conditions, differentiated thyroid cells or even unusual tumors may arise.     

Immunocytochemical localization of renin in the submandibular gland of the mouse during postnatal development.

The localization of renin in the developing mouse submandibular gland was studied immunocytochemically using the unlabelled antibody-enzyme method of Sternberger ('74). Bouin-fixed submandibular glands of mice of both sexes were examined at 5-day-intervals from birth (day 0) to 50 days of age. At all stages studied, only granular convoluted tubule (GCT) cells stained immunocytochemically for renin; such cells were first seen in glands of 30-day-old males and of 30-day-old females. The size and number of renin-containing GCT cells increased rapidly in males, attaining adult status by 50 days of age. In females, differentiation of GCT cells immunoreactive for renin was slower and less regular than in males, and at 50 days of age the GCT segment had not yet reached adult conditions with respect to the distribution of renin. Renin appears in GCT cells at later ages than other GCT cell products (e.g., EGF and amylase), suggesting the existence of independent developmental control for the expression of various biologically active substances in the GCTs.     

Effect of neonatal sympathectomy on the postnatal differentiation of the submandibular gland of the rat

Summary Right superior cervical sympathectomy was performed in one-day old rats. This operation had a small but definite effect on the postnatal development of the submandibular gland. The gland on the sympathectomized side weighed less and contained smaller amounts of DNA, RNA and protein than the contralateral intact gland. The postnatal development of acinar cells and granular convoluted ductal cells was retarded in the sympathectomized gland. The acinar cells which differentiated after the ganglionectomy were smaller than those in the contralateral intact gland and were filled with secretory granules but devoid of basal basophilia. The rate of cellular proliferation in the sympathectomized gland was, however, similar to that in the intact gland at various ages studied.Supported by Public Health Service Research Grant CA 17038 from the National Cancer Institute to Dr. T. Barka. The authors are indebted to Miss H. van der Noen and Mr. I. Borcsanyi for their assistance and to Dr. T. Barka for his suggestions regarding this paper     

The postnatal development of the submandibular gland of the mouse

Summary The postnatal development of the submandibular gland was investigated in male mice of the Swiss-Webster strain, which were killed at 1, 2, 3, 4, 5, 6, 8, 10, 12, 16 and 20 weeks of age, while the older mice had been weaned at 3 weeks of age. The mean weight of the submandibular gland increases from 9.5 mg at 1 week to 232.9 mg at 20 weeks of age, and the rate of increase is rapid between 3 and 10 weeks of age. The gland's contents of DNA, RNA and protein increase in a similar manner.The changes in the constituent cell types of the gland were studied in radioautographs prepared from Epon-embedded sections of mice given ³H-thymidine and stained with toluidine blue. At 1 week of age, the gland consists of acinar cells (36%), intercalated duct cells (26%), juxta-acinar cells (13%), striated duct cells (12%) and others. The cellular composition of the gland changes little before weaning, but the absolute number of all types of cells increases with age. Between 3 and 4 weeks, juxta-acinar cells disappear and granular convoluted tubule cells appear and increase rapidly in number with age. The rapid expansion of the population size of granular convoluted tubule cells after weaning coincides with the second peak of increased proliferative activity of intercalated duct cells, whereas all the other cell types show a progressive decrease in their proliferative activity with age. In spite of the burst in proliferative activity, there is no corresponding increase in the absolute number of intercalated duct cells. The number of striated duct cells peak at 5 weeks of age and then declines. These findings indicate that the mitoses of intercalated duct cells give rise to granular convoluted tubule cells through a stage of striated duct cells. At 20 weeks of age, the gland consists of granular convoluted tubule cells (47%), acinar cells (28%), intercalated duct cells (12%), striated duct cells (1%) and others.Supported by Public Health Service Research Grant AMDE 19753 from the National Institute of Health. The authors are indebted to Mr. I. Borcsanyi for technical assistance