Differential distribution of some extracellular matrix fibers in an experimentally denervated rat megaileum

Comparison of the structural and ultrastructural characteristics of the female prostate between pregnant and non-pregnant plains viscacha (Lagostomus maximus)

Some years ago, our group reported the presence of the female prostate in all the studied females of the plains viscacha (Lagostomus maximus). The goal of the present study was to characterize and compare the female prostate gland between adult pregnant and non-pregnant plains viscacha using histochemical, lectin-histochemical and immunohistochemical techniques, as well as optic and electron microscopy. Structurally, alveoli are lined by a simple epithelium formed by different cell types: basal cells, secretory cells in different stages of the secretory cycle and cells of clear cytoplasm. Secretory cells are the most abundant cell type, differing between them depending on the quantity and electron-density of their granules. The basal cells are less abundant and are responsible for the renewal of the alveolar epithelium. Likewise, other cells with secretory morphology were found in all the studied females; these have a clear cytoplasm, few granules and mitochondria. It could be considered that they are degranulated secretory cells or that they have partially released their granules. The stroma of the organ is formed by connective tissue and smooth muscle fibers, which are immunohistochemically evidenced against desmin. Histochemical and lectin-histochemical analysis revealed the presence of different glucidic residues in the different cell types. No structural, histochemical, lectin-histochemical, and ultrastructural differences were observed between pregnant and non-pregnant females of plain viscachas, except for the expression of some lectins. The paraurethral gland of Lagostomus maximus can be used as a model for studying the gland in other species since its structural and ultrastructural characteristics do not depend on the hormonal status of the female.

Skin Changes Due to Massive Weight Loss: Histological Changes and the Causes of the Limited Results of Contouring Surgeries

PURPOSE

Outcomes of body contouring surgeries in patients who previously had obesity are limited because of the loss of skin quality. This study aimed to evaluate the morphometric characteristics of collagen and elastic fibers of the skin in the abdominal epigastric region of patients who had massive weight loss following bariatric surgery and compared such with the skin characteristics of patients with morbid obesity.

METHODS

This observational study compared skin fragments from the epigastric region of 20 patients who had massive weight loss due to bariatric surgery and 20 patients with morbid obesity. The morphometric analysis was performed on the collagen system using the Picrosirius/polarized light method and on the elastic system using the Weigert's resorcin-fuchsin method.

RESULTS

Reduction of thick collagen fibers (p = 0.048), increased thin collagen fibers (p = 0.0085), and increased elastic fiber density (p < 0.001) were observed in the massive weight loss group. No differences were found between the groups regarding mean age (p = 0.917) and total amount of collagen fibers (p = 0.3619). Structural dermis alterations in the massive weight loss group demonstrated collagenous remodeling, with consequent reduction of thick, organized, structured, and directed fibers in favor of thin, misaligned, and loosely arranged fibers. Weight loss was also associated with increased skin elasticity.

CONCLUSION

The morphometric changes in the collagen and elastic system scientifically explained the already established clinical perception of cutaneous alterations in patients who had massive weight loss following bariatric surgeries.

Myenteric Denervation of the Gut with Benzalkonium Chloride: A Review of Forty Years of an Experimental Model

Experimental denervation of organs plays a key role in understanding the functional aspects of the normal innervation as well as the diseases related to them. In 1978 the experimental model of myenteric denervation of the rat gut by serosal application of benzalkonium chloride (BAC) was proposed. BAC is a positively charged surface-active alkylamine and is a powerful cationic detergent, which destroys bacteria after ionic attraction and for this reason is largely used as a surgical antiseptic. Since its initial report, the BAC-induced myenteric denervation model has been used to study many functional and pathological aspects of the enteric nervous system. So far this is the only pure method of myenteric denervation available for research in this area. Promising reports in the literature have shed light on the possibilities for the development of new uses of the BAC-denervation experimental model as a therapeutic tool in some pathological situations. This review aims to shed light on the main historical and recent findings provided by this experimental model.

Enteric nervous system assembly: Functional integration within the developing gut

Co-ordinated gastrointestinal function is the result of integrated communication between the enteric nervous system (ENS) and "effector" cells in the gastrointestinal tract. Unlike smooth muscle cells, interstitial cells, and the vast majority of cell types residing in the mucosa, enteric neurons and glia are not generated within the gut. Instead, they arise from neural crest cells that migrate into and colonise the developing gastrointestinal tract. Although they are "later" arrivals into the developing gut, enteric neural crest-derived cells (ENCCs) respond to many of the same secreted signalling molecules as the "resident" epithelial and mesenchymal cells, and several factors that control the development of smooth muscle cells, interstitial cells and epithelial cells also regulate ENCCs. Much progress has been made towards understanding the migration of ENCCs along the gastrointestinal tract and their differentiation into neurons and glia. However, our understanding of how enteric neurons begin to communicate with each other and extend their neurites out of the developing plexus layers to innervate the various cell types lining the concentric layers of the gastrointestinal tract is only beginning. It is critical for postpartum survival that the gastrointestinal tract and its enteric circuitry are sufficiently mature to cope with the influx of nutrients and their absorption that occurs shortly after birth. Subsequently, colonisation of the gut by immune cells and microbiota during postnatal development has an important impact that determines the ultimate outline of the intrinsic neural networks of the gut. In this review, we describe the integrated development of the ENS and its target cells.

Effects of myenteric denervation on extracellular matrix fibers and mast cell distribution in normal stomach and gastric lesions

BACKGROUND

In this study the effect of myenteric denervation induced by benzalconium chloride (BAC) on distribution of fibrillar components of extracellular matrix (ECM) and inflammatory cells was investigated in gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Rats were divided in four experimental groups: non-denervated (I) and denervated stomach (II) without MNNG treatment; non-denervated (III) and denervated stomachs (IV) treated with MNNG. For histopathological, histochemical and stereological analysis, sections of gastric fragments were stained with Hematoxylin-Eosin, Picrosirius-Hematoxylin, Gomori reticulin, Weigert's Resorcin-Fuchsin, Toluidine Blue and Alcian-Blue/Safranin (AB-SAF).

RESULTS

BAC denervation causes an increase in the frequency of reticular and elastic fibers in the denervated (group II) compared to the non-denervated stomachs (group I). The treatment of the animals with MNNG induced the development of adenocarcinomas in non-denervated and denervated stomachs (groups III and IV, respectively) with a notable increase in the relative volume of the stroma, the frequency of reticular fibers and the inflammatory infiltrate that was more intense in group IV. An increase in the frequency of elastic fibers was observed in adenocarcinomas of denervated (group IV) compared to the non-denervated stomachs (group III) that showed degradation of these fibers. The development of lesions (groups III and IV) was also associated with an increase in the mast cell population, especially AB and AB-SAF positives, the latter mainly in the denervated group IV.

CONCLUSIONS

The results show a strong association in the morphological alteration of the ECM fibrillar components, the increased density of mast cells and the development of tumors induced by MNNG in the non-denervated rat stomach or denervated by BAC. This suggests that the study of extracellular and intracellular components of tumor microenvironment contributes to understanding of tumor biology by action of myenteric denervation.