Abstract

Monitor lizards are acclimatized to a variety of environments. Most of the monitor species are terrestrial, although there are arboreal and semiaquatic monitors. Such accommodation requires unique cellular structure and regulatory devices in various organs, particularly their lungs. This study aimed to report the pulmonary guardians and special regulatory devices that may guard and promote the function of the lungs of the Nile monitor lizards (Varanus niloticus). Specially structured vessels were recorded in the pulmonary tissue involving atypical glomus vessels, vessels with variable wall thickness, and a venule with specialized internal elastic membrane. Moreover, numerous lung resident guardians could be identified including both alveolar and interstitial macrophages, dendritic cells, mast cells, and B- and T-lymphocytes. Pericytes were demonstrated surrounding the capillary endothelium with a characteristic direct hetero-cellular junction with telocytes. Telocytes established a microenvironment through an indirect hetero-cellular junction with the interstitial macrophage, dendritic cells, and pneumocyte type II. Collectively, these data indicate a significant role played by the specially structured vessels and the resident immune cells in guarding the pulmonary tissue of the Nile monitor lizards and promoting its function. Telocytes are suggested to play a key role in angiogenesis and cellular communication to promote the function of the immune cells.

Wounds can be a result of surgery, an accident, or other factors. There is still a challenge to find effective topical wound-healing agents. This study aims to investigate the wound-healing activity of chemical and green synthesized chitosan nanoparticles (Ch-NPs) using Lawsonia inermis leaves extract. The nanoparticles were morphologically and chemically characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and high-resolution transmission electron microscopy (HRTEM). Forty-five adult female albino rats were randomly divided into three groups. The cutaneous surgical wounds were topically treated with 0.9% normal saline (control group), green Ch-NPs (second group), and chemical Ch-NPs gels (third group), respectively. The clinical picture of wounds and histopathological changes were assessed on the 3rd, 7th, 14th, and 21st days post-treatment. X-ray diffraction analysis revealed great crystallinity and purity of nanoparticles. The studied nanoparticles increased the wound contraction percent (WC%), reduced healing time and wound surface area (WSA), and these results were backed up by histological findings that indicated improved epithelialization, dermal differentiation, collagen deposition, and angiogenesis in treated rats compared with control rats (p < 0.05). We concluded that the wound-healing effects of the studied nanoparticles are encouraging, and further studies for complete assessment are still needed.

The fish epidermis (EP) contains several cell types, and it has several functional roles, though the secretory role prevails. The alarm or epidermal club cells (ECCs) represent a voluminous immune cell secreting an alarm substance. Our work targeted the histochemical and immunologic attributes of the ECCs in catfish. Matrix metalloproteinase (MMP-9) immunostaining revealed strong immunoreactive signals in the cytoplasm of all ECCs, while S-100 protein immunoreactivity selectively marked the ECCs. Individual ECCs exhibit intense S-100 immunoreactivity compared to neighboring ECCs. The difference in the intensity of the S-100 immunostaining was associated with the difference in the ECC size. This was confirmed by the semithin results where several developmental stages of ECCs could be distinguished. Some eosinophilic granular cells with their characteristic metachromatic granules were recorded juxtaposing the ECCs. Moreover, some free electron-dense granules could be demonstrated in the intercellular spaces surrounding the ECCs. Collectively, these findings suggest several functional profiles for the catfish ECCs depending on their developmental stage. Most importantly, S-100 immunoreactivity in the ECCs suggests its neuroendocrine function. Moreover, the difference in the intensity and polar distribution of S-100 staining is a sign of its role in the differentiation of the ECCs.

Piscine mast cells or eosinophilic granule cells (EGCs) of fish are equivalent to the mammalian mast cells. Recently, a better understanding of EGCs functions is allowed because of the growing interest in fish models. Herein, we present a trial to furnish data regarding the distribution of the EGCs in the fish olfactory organ, an issue that has not been reported so far. Regarding their distribution, two kinds of EGCs had been identified. An intra-epithelial one was detected in the olfactory epithelium lining of the olfactory lamellae. The stromal one was identified in the connective tissue core of the olfactory lamellae and in the lamina propria underlying the olfactory epithelium. Some were detected in the capillary lumen. The cytoplasm of the EGCs reacted strongly with the MMP-9 antibody. Stimulating a migration perspective for the olfactory EGCs which was confirmed by their location in the blood capillaries. Several EGCs could be verified in close relation, some underneath the epineurium, with the nerve fiber. Mutually, this verifies the existence of intra-epithelial and stromal migrating EGCs in the catfish olfactory organ and their inclusion in the olfactory immune response. Additionally, this provides evidence for an immune–nervous interaction to influence both the immune reactions and the nervous scheme in catfish.