Morphometric Study of Diabetes Related Alterations in Human Parotid Gland and Comparison with Submandibular Gland.

Type 2 diabetes mellitus represents one of the principal diseases that afflict the world population and is often associated with malfunction of salivary glands and consequent oral diseases. We recently described significant ultrastructural alterations in the human submandibular gland in diabetic patients without evident oral pathologies. Herein, an analogs morphometrical investigation was focused on the parotid gland in order to evaluate if one of the two glands is more affected by diabetes. Parotid fragments from diabetic and nondiabetic patients were fixed, dehydrated, and processed for light and electron microscopy. Serous cells were randomly photographed and the density and size of several structures involved in the secretory process were examined by morphometry. Scanning electron microscopy images revealed significant changes in the number of apically docked granules and vesicles, suggesting that the last steps in exocytosis are somehow altered in diabetic cells. Other variables analyzed by light and transmission electron microscopy such as the size of acini and secretory granules did not show significant changes, but comparison with previous data obtained with submandibular gland cells demonstrated that the two glands are affected differently.

Diabetes causes morphological changes in human submandibular gland: a morphometric study.

BACKGROUND: Dataon structural alterations in human diabetic salivary glands are scanty and conflicting. The goal of this study is based on the evaluation of the morphological changes in submandibular glands of subjects with well-controlled diabetes and without evident salivary malfunctions. METHODS: Submandibular gland pieces from diabetic and non-diabetic patients were fixed, dehydrated, and processed to obtain sections for light and electron microscopy. Randomly selected micrographs were statistically analyzed to reveal variations in serous acini. RESULTS: Morphometrical evaluation allowed us to reveal significant changes such as enlargement of acinar and granule size, reduction of mitochondrial size, increased density of microbuds and protrusions along luminal membranes. CONCLUSIONS: The results indicate that diabetes affects submandibular gland structure even when glandular function appears unaltered and suggest that morphological changes reflect functional changes chiefly regarding the secretory activity.

Morphological evidence that pentagastrin regulates secretion in the human parotid gland.

Salivary secretion is principally regulated by autonomic nerves. However, recent evidence from in vivo animal experiments suggests that gastrointestinal peptide hormones can also influence saliva production. The aim of the present study was to define the secretagogue activity of the gastrin-analogue pentagastrin in human salivary glands. For this purpose, parotid tissues were exposed to pentagastrin in vitro. Morphological techniques were used to evaluate modifications to serous acinar cells associated with secretion. Using a variant of the osmium maceration method, high resolution scanning electron microscopy allowed assessment of the morphology of the cytoplasmic aspect of the plasmalemma to demonstrate secretory activity. To quantify responses to pentagastrin, we recorded morphometric data on microvilli, microbuds, and protrusions. Dose-dependent morphological changes were observed, whereas protein concentration increased in the incubate. The use of selective receptor antagonists showed pentagastrin to act principally via cholecystokinin-A receptors. The morphological responses observed following exposure to pentagastrin differed from those elicited following exposure to the pan-muscarinic agonist carbachol. This study provides the first demonstration of a direct secretory action of gastrointestinal peptides on salivary glands in humans.

Immunoreactivity of the salivary protein statherin in human male accessory sex glands.

BACKGROUND: Statherin is a small phosphoprotein chiefly studied for its protective roles towards teeth and oral tissues. Although generally considered as exclusively secreted by salivary glands, circumstantial evidences suggested that other tissues also produce it. This article first demonstrates statherin immunoreactivity in human prostate and seminal vesicles. METHODS: Surgical samples of prostate and seminal vesicles were fixed in a mixture of paraformaldehyde and glutaraldehyde, and embedded in Epon resin without previous osmication. Ultrathin sections were treated for the intracellular localization of statherin by means of an immunogold staining method. RESULTS: Reactive statherin was revealed in secreting cells of both seminal vesicle and prostate epithelia: labeling was found in secretory granules of seminal vesicle cells and in cytoplasmic vesicles of prostatic cells. CONCLUSIONS: The different staining patterns suggested that the two glands secrete statherin through different pathways. Prostate 71:671-674, 2011. © 2010 Wiley-Liss, Inc.

Electron microscopic immunogold localization of statherin in human minor salivary glands.

In this study, which supplements a recent article on the localization of statherin in human major salivary glands, we investigated the intracellular distribution of this peptide in minor salivary glands by immunogold cytochemistry at the electron microscopy level. In the lingual serous glands of von Ebner, gold particles were found in serous granules of all secreting cells, indicating that statherin is released through granule exocytosis. In buccal and labial glands, mostly composed of mucous tubuli, statherin reactivity was detected in the serous element, which represents only a small population of the glandular parenchyma. In these serous cells, however, statherin labeling was absent in secretory granules and restricted to small cytoplasmic vesicles near or partially fused with granules. Vesicle labeling could be related to the occurrence of an alternative secretory pathway for statherin in buccal and labial glands.

Oxytocin immunoreactivity in the human urethral (Littrè's) glands.

Oxytocin is a cyclic nonapeptide whose best known effects are stimulation of uterine smooth muscle cells during labor and of milk ejection during lactation. Circulating oxytocin originates from the hypothalamus, but its production has also been documented in peripheral tissues. Furthermore, seminal plasma also contains oxytocin, but its functional role is still unknown, although its secretion is generally ascribed to the prostate. In this study, we investigated the possibility that seminal oxytocin is also secreted by other exocrine glands of the human male genital tract. Intramural (Littrè's) glands isolated from bioptic specimens of normal urethrae were processed for immunogold localization of oxytocin. Immunostaining was detected in principal cells, with gold particles specifically found on secretory granules. Basal and endocrine cells were unstained. The present findings suggest that urethral glands not only produce the mucinous layer that protects and lubricates the urethral wall, but also are potential sources of other seminal components, such as oxytocin, which probably play still unclear roles in reproductive physiology.

A simple method to obtain en face sections of flat tissue culture cells.

A method is described for embedment of multiple confluent sheets of flat tissue culture cells that permits sectioning for thin or semithin sections in precise planes. The technique is especially useful for obtaining en face sections.

Salivary histatins in human deep posterior lingual glands (of von Ebner).

OBJECTIVE: Human saliva contains a family of low molecular weight histidine-rich proteins, named histatins, characterised by bactericidal and fungicidal activities in vitro against several microbial pathogens, such as Streptococcus mutans and Candida albicans. They represent a major component of an innate host non-immune defense system. In an earlier study we described the distribution of histatins in the glandular parenchyma of human major salivary glands, confirming that all human major salivary glands are involved in the secretion of histatins into saliva. In the present study we determined the expression and localisation of histatins in human posterior deep lingual glands (von Ebner's glands) by means of immunoelectron microscopy. DESIGN: Thin sections of normal human salivary glands, embedded in Epon resin, were incubated with rabbit polyclonal antibodies specific for human histatins and successively with a gold conjugated goat anti-rabbit IgG used as secondary antibody. Sections incubated with medium devoid of primary antibody or containing non-immune serum were used as controls. RESULTS: The serous secreting cells represented the main source of histatins in the glandular parenchyma of von Ebner's glands. At the electron microscopic level, labeling was associated with rough endoplasmic reticulum, Golgi complex and secretory granules that represented the main cytoplasmic site of histatin localisation. However, variability in the intensity of labeling was observed among adjacent cells. CONCLUSIONS: The present results show for the first time that human von Ebner's glands produce and represent a significant source of histatins, supporting the hypothesis of their important role in preventing microbial assaults on the tissues in the posterior region of the tongue and in the circumvallate papillae.