Scanning electron microscopy of the nasal skin in different animal species as a method for forensic identification

Sublingual floor of Rahmani sheep (Ovis aries): A scanning electron microscopy and histomorphology analysis

The current study investigated the sublingual floor of Rahmani sheep (Ovis aries). Samples from nine healthy adult sheep have been analysed using morphometrical, scanning electron microscopic (SEM), and histological examination. The sublingual floor of the sheep was formed of a rostral prefrenular part (spatula-shaped) and two lateral sublingual recesses. Right and left sublingual caruncles were asymmetrical in length and each one had a serrated border, divided into three papillae. At higher magnifications, the three papillae of the sublingual caruncle's edge were variable in shape, with other two papillae were demonstrated underneath the caruncle. Each sublingual recess had a sublingual fold (plica sublingualis) extended from the level of frenulum linguae till the glossopalatine arch, bordered with caudolaterally directed papillae till the level of first lower molar cheek teeth. The sublingual salivary glands were mixed (seromucoid) type. The glandular lobule consisted of mucous acini and sporadic serous acini, as well as the presence of some mucous acini capped by acidophilic cells, serous demilunes. The mucous acinus was formed of pyramidal mucous cells with pale stained cytoplasm and basally located nuclei. Two ducts; major sublingual and submandibular ducts were observed within the submucosa of the sublingual caruncle. The sublingual ductal pseudostratified columnar epithelium was interspersed by more goblet cells than that of the submandibular duct. Collagen fibres around the glandular lobules, intralobular and interlobular excretory ducts as well as the connective core of the papillae were noticed. By SEM, two epithelium-lined pits on the surface of the sublingual floor mucosa caudal to the central incisive teeth were termed orobasal organ. As the first study to give a comprehensive analysis of the sheeps' sublingual floor, this one serves as a baseline for future clinical studies.

Histological and ultrastructural characterization of the dorso-ventral skin of the juvenile and the adult starry puffer fish (Arothron stellatus, Anonymous 1798)

BACKGROUND

The starry puffer fish (Arothron stellatus, Anonymous, 1798) is a poisonous tetradontidae fish inhabiting the Red sea. The skin constitutes an important defense against any external effects. The study aims to characterize the dorso-ventral skin of the juvenile and the adult starry puffer fish using light and scanning electron microscopies. Twenty specimens of juvenile and adult fresh fishes were used.

RESULTS

The scanning electron microarchitecture of the skin of the juvenile and adult fish showed delicate irregular-shaped protrusions, and well-defined bricks-like elevations on the dorsal side and interrupted folds as well as irregular-shaped protrusions on the ventral side. In adult fish, the patterned microridges of the superficial and deep epithelial cells (keratinocytes) were larger and well-defined in the dorsal skin than in the ventral side, the contrary was seen in the juvenile fish. The microridges were arranged in a fingerprint or honeycomb patterns. The openings of the mucous cells were more numerous in the dorsal skin in both age stages but more noticeable in adult. Furthermore, the sensory cells were more dominant in the juveniles than the adults. The odontic spines were only seen in adult. Histologically, few taste buds were observed in the epidermis of the dorsal skin surface of the adult fish. Both mucous and club cells were embedded in the epidermis of the juvenile and adult fish with different shapes and sizes. Melanophores were observed at the dorsal skin of both juvenile and adult fishes while fewer numbers were noticed at the ventral surfaces. Several dermal bony plates with different shapes and sizes were demonstrated in the skin of both adult and juvenile fishes.

CONCLUSION

The structural variations of skin of the juvenile and adult fishes may reflect the various environmental difficulties that they confront.

Preen gland of the laughing dove (Streptopelia senegalensis aegyptiaca): Light and electron microscopic analysis

This work reviews the microscopic anatomy of the preen gland in laughing dove (Streptopelia senegalensis aegyptiaca) using light, scanning, and transmission electron microscopes. The gland possessed two large pea-shaped lobes. The glandular lobules of each lobe were huddled in elliptical, triangle, round shapes, connected with each other by strands of connective tissue septae. The lobule was composed of glandular follicles, each follicle folded and enclosed by a sheath of connective tissue connected with the neighboring ones by interfollicular septae. The gland's parenchyma was coated with a dense connective tissue capsule composed of collagen, elastic, and reticular fibers. The secretory tubules were divided into peripheral tubules and central tubules. The central ones were located close to the major cavity and lined with thin epithelium, whereas the peripheral tubules were adjacent to the capsule and characterized by taller epithelium. The central secretory tubules were lined with four cell layers: flattened basal, large-sized polyhedral intermediate, and secretory cell layers, as well as a degenerative cells layer that formed of small cells with pale cytoplasm and pyknotic nuclei. Variable sizes and shapes of Herbst corpuscles were detected alongside the papillary duct and near the glandular lobe. Transmission electron microscopy view revealed that the cytoplasm of the intermediate cells contained a dense population of mitochondria, while the secretory and degenerative cells contained fewer mitochondria. In conclusion, these structures will be beneficial for understanding the habitat differences of laughing doves. RESEARCH HIGHLIGHTS: Grossly, the preen gland (PG) of the laughing dove formed of two large pea-shaped lobes. The glandular lobule was composed of glandular follicles, each follicle was folded and enclosed by a sheath of connective tissue connected with the neighboring ones by interfollicular septae. The central secretory tubules were lined with four cell layers: basal, intermediate, secretory, and degenerative cell layers. Variable sizes and shapes of Herbst corpuscles were detected alongside the papillary duct and near the glandular lobe of the PG. In transmission electron microscopic analysis, the cytoplasm of the intermediate cells contained a dense population of mitochondria, while the secretory and degenerative cells contained fewer mitochondria.

Morphological and ultrastructural features of the laryngeal mound of Egyptian Cattle Egret (Bubulcus ibis, Linnaeus, 1758)

Background

According to our acknowledgment this is the first full anatomical description of the studied laryngeal mound of the Egyptian Cattle Egret (Bubulcus ibis, Linnaeus, 1758). This study was obtained with the aid of scanning electron microscopy (SEM) and histological techniques. Heads of ten healthy adult male Egyptian cattle egrets were used in this study.

Results

The laryngeal mound (Mons laryngealis) was a pear-shaped musculoskeletal elevation. It represented 20.55 and 67.87% of the total length of the oropharyngeal floor and the pharyngeal floor, respectively. By SEM view, the lateral aspect of the caudal third of the laryngeal mound had a serrated mucosal appearance, forming of 6–7 finger-like projections. Furthermore, the terminal part of the laryngeal mound (except the middle part) was bordered a transverse row of pyramidal-shaped papillae, which demarcated from the esophagus. Histologically, laryngeal salivary glands termed (cricoarytenoid salivary glands) of the laryngeal mound were simple tubular type and were arranged in one row within the lamina propria connective tissue close to the lamina epithelialis. Those glands were surrounded by abundant aggregation of lymphocytes, extended overlying the surface lining epithelium. The glottis within the laryngeal mound was supported by hyaline cartilages; dorsally by paired arytenoid cartilages, ventrolaterally by cricoid cartilage, and caudodorsally by procricoid cartilage. Two groups of intrinsic laryngeal skeletal muscles have connected the cartilages. The glandular epithelium of the laryngeal salivary glands and chondrocytes of the laryngeal cartilages showed strongly positive alcian blue reaction.

Conclusions

The laryngeal mound shows certain features that are unique as an adaptation to lifestyles and bird’s habitat.

Histomorphology and ultrastructure of the proventriculus of the broad breasted white turkey (Meleagris gallopavo, Linnaeus 1758)

This study aims to examine the functional morphology of the proventriculus of the broad breasted white turkey (BBWT) (Meleagris gallopavo, Linnaeus 1758) using gross anatomy, light microscopy, gross/histomorphometric analysis, and scanning and transmission electron microscopy. The proventriculus was characterized internally by many elevated papillae with a mound, leafy flower, and lotus flower-shapes. Each papilla was enclosed by concentrically organized mucosal folds with distinct or indistinct proventricular gland openings on its top. Longitudinal folds and grooves at the junction of the proventriculus with the esophagus exhibited various sized and shaped openings of esophageal glands with irregular outlines. Histologically, the surface epithelium of the proventriculus was covered by a thin layer of cuticle, particularly evident at its junction with the gizzard. The lamina epithelialis and propria, and secretory units of proventricular lobules were infiltrated by aggregations of lymphocytes and lymphoid follicles (nodules). Variably shaped glandular lobules of proventricular glands occupied the submucosa, surrounded by thin strands of smooth muscle fibers derived from muscularis mucosa. Triangular, cuboidal, or columnar-shaped secretory oxyntico-peptic cells lined the secretory units. Many telocytes (pyramidal or fusiform-shaped cell bodies with lengthy telopodes) were observed in interstitial tissue. Further, two types of argyrophilic endocrine cells were identified within the glandular epithelium. The morphology of the M. gallopavo proventriculus reflects its dietary habits and behavior.