The current study investigated the morphological, histochemical, and immunohistochemical characteristics of alarm cells and their precursors in ruby-red-fin shark (rainbow shark), Epalzeorhynchos frenatum (Teleostei: Cyprinidae). Precursor alarm cells were shown to be small, cuboidal, pyramidal, or round in shape, with eosinophilic cytoplasm, resting on the basement membrane of the epidermis. The cells later elongated to become columnar in shape. Subsequently, they enlarged and became large oval-shaped cells. They then underwent shrinkage and vacuolation. The superficial alarm cells were collapsed. Alarm cells were found to have an affinity for different histochemical stains, including bromophenol blue, iron hematoxylin, Sudan black, Mallory triple trichrome, Crossman's trichrome, Safranin O, and Weigert's stains, as well as lipase and alkaline phosphatase. Endocrine properties of the alarm cells were identified by silver staining and synaptophysin immunostaining. Alarm cells exhibited stemness activities and had a strong immunoaffinity for CD117. They had a proteolytic function, as identified by lysosome-specific staining with acridine orange and strong immunoaffinity for matrix metalloproteinase (MMP-9). They also exhibited proliferatively, reflected by immunological staining by proliferating cell nuclear antigen. In conclusion, alarm cells are unique epidermal cells with multiple functions. They play immunological, and endocrine, roles. They also retain stemness and proliferative properties.

Teleosts exhibit enormous heterogeneity in brain morphology, especially in the patterns of the organization of cerebellum. The cerebellum of a red-tail shark that we analyzed was well-developed and included three main divisions: the valvula cerebelli, the corpus cerebelli, and the vestibulolateral lobe. Characteristically, the cerebellar cortex contained three well-distinct layers: an outer molecular, intermediate ganglionic, and inner granular layer. The ganglionic layer possessed irregularly arranged Purkinje cells and eurydendroid cells that extended their processes into the molecular layer. Both Purkinje cells and eurydendroid cells showed immunoreactivity for iNOS2. Moreover, astrocytes in the cerebellum showed the expression of glial fibrillary acidic protein. The most striking observation in the cerebellum of shark was the lack of deep cerebellar nuclei and a well-identified white matter. On the other hand, the gray substance in the spinal cord displays a characteristic pattern in its organization, in which the dorsal horns lie quite close together, giving the gray substance the shape of an inverted Y and possessing large neurons. Notably, the white matter possessed myelinated nerve fibers. The current study provides the first report on the organization of layers and neurons in the cerebellum and spinal cord of red-tail shark. This research will contribute to the neuroanatomy and evolutionary studies of the brain of Cyprinidae.

Specific features of the immunohistochemical and ultrastructural organization of the hemopoietic head-kidney (HK) in adult Ctenopharyngodon idella (Valenciennes, 1844) were investigated using light and transmission electron microscopy. The HK of grass carp possessed all developmental stages of leucocytes and erythrocytes, as well as dendritic cells and epithelial reticular cells. The rodlet cells were expressed α-smooth muscle actin (SMA). In addition, macrophages were the most numerous cells in the HK, which aggregated into structures called melanomacrophage centers (MMCs). On contrary, the chromaffin and interrenal cells (ICs) were mixed and organized into large anastomosing cords, which lined the posterior cardinal veins of the HK, and associated with many blood capillaries. The ICs displayed the characteristic features of steroid-producing cells. Three types of chromaffin cells: adrenaline, noradrenaline, and small granule-containing cells were observed in the HK. Glial fibrillary acidic protein (GFAP)-positive sustentacular cells were marked among the chromaffin cells. Hemopoietic cells, immune cells, MMCs, rodlet cells, in addition to three types of chromaffin cells and one type of interrenal cells in the HK were correlated with the functional significance of the fish concerned.

The staining procedure is critical for investigating intra- and extra-cellular ultrastructure of microorganisms by transmission electron microscopy (TEM). Here, we propose a new ultra-low lead staining (ULLS) technique for preparing the ultrathin sections for TEM analysis. Sections of Enterobacter sp. (bacteria), Aspergillus niger (filamentous fungi), Rhodotorula mucilaginosa (fungi), and Chlamydomonas reinhardtii (microalgae) were tested. Compared with the sections prepared by the typical double-staining technique, ULLS-based sections showed evident advantages: (i) the staining process only required the addition of Pb(NO3)2; (ii) the Pb level during incubation was set as low as 1 mg/L, which had negligible toxicity to most microbial cells; (iii) the Pb cations were added during microbial culture, which avoided complicated sample preparation as in typical double staining. Taking C. reinhardtii as an example, the ULLS technique allowed fine investigation of microbial ultrastructure, e.g., starch granule, mitochondrion, Golgi apparatus, vacuole, and vesicle. Meanwhile, the physiological processes of the cells such as cell lysis and exocytosis were successfully captured, with relatively high contrast. This study hence shows a bright future on preparation of the high-quality ultrathin sections of microbial cells by the ULLS technique.

This research reports for the first time the anatomical characteristics of all species belonging to Baccharis subgenus Coridifoliae (Asteraceae). The anatomy and micro-morphology of aerial vegetative organs of ten species: B. albilanosa, B. artemisioides, B. bicolor, B. coridifolia, B. erigeroides, B. napaea, B. ochracea, B. pluricapitulata, B. scabrifolia, and B. suberectifolia are investigated by light and scanning electron microscopy. The number of secretory ducts, crystal morphology, presence or absence of conical nonglandular trichomes, leaves cross-section shape, margin morphology, anticlinal epidermal cell walls shape, and cuticle structure were identified as characters with diagnostic value for species. Similarity cluster analysis allows the formation of three groups based on a percentage of similarity between 45 and 84%. Some species showed differential characteristics as the presence of up to four secretory ducts in the midrib in B. albilanosa; smooth cuticles onboth sides of the leaf epidermis in B. erigeroides; flat midrib shape on both sides of the leaves in B. napaea; and convex–flat midrib shape in B. suberectifolia. The remaining species can be differentiated by a set of anatomical features. Anatomical and histochemical characteristics of stems and leaves provided data to support species identification.

The leaf skeletonizer, Eutectona machaeralis (Walker) (Lepidoptera: Crambidae), is a severe insect pest of teak trees (Tectona grandis L.f.) in China. To provide some basic evidence for future semiochemical-based management strategies of E. machaeralis, the morphology, ultrastructure, and distribution of antennal sensilla of adults were observed under scanning and transmission electron microscopy. The shape and structure of antenna were similar between males and females, both being filiform. However, the antennal length of males was significantly longer than that of females. Eight morphological sensilla types were observed in both sexes: Böhm's bristles, sensilla trichodea, sensilla basiconica, sensilla chaetica, sensilla styloconica, sensilla coeloconica, sensilla auricillica, and sensilla squamiformia. Significant sexual dimorphism of the sensilla dimensions was found, especially in sensillar length. The putative and potential functions of the different sensilla types are discussed based on the fine structures of the cuticular walls and dendrites of the different sensilla types. We expect these results to help lay a solid foundation for future functional research and develop further investigations of E. machaeralis.

The myotendinous junction (MTJ) is the interface between muscle and tendon, and it is the main area of force transmission of the locomotor apparatus. Dystrophic processes promote pathological injury which affects the skeletal muscle and can influence the morphology of the MTJ. This study aimed to investigate the adaptations in MTJ morphology of mdx mice in the tibialis anterior muscle. Male mice (n = 24) were divided into Control—C57bl/10 and mdx—C57bl/10mdx (Duchenne muscular dystrophy experimental model). In the mdx group, centralized nuclei with a large area and greater deposition of type III collagen (fibrosis) were observed. Also, shorter sarcomeres and sarcoplasmatic projections of MTJ were observed. We concluded that the adaptations in mdx mice demonstrated extensive impairment in the MTJ region with reduced ultrastructures.

This paper provides detailed anatomy and histochemistry of the leaves and stems of Eucalyptus tereticornis illustrated with brightfield and scanning electron microscopy. The key microscopic features that can aid in the species identification include the presence of crust-like epicuticular waxes on the leaf surfaces, platy aggregations of cluster crystals in the epidermal cells, presence of prismatic crystals in the epidermal cells, in the parenchymatous sheath in the blade and petiole, and in the cortex and pith of the stems, and leaf homogenous mesophyll consisting of palisade cells. Histochemical analyses confirmed the presence of lipophilic and phenolic compounds in the contents of secretory cavities, starch grains in the xylem parenchyma of the stem, and lignified elements in the sclerenchymatous ring adjoining the phloem and in the xylem in the leaves and stems.

Ectopic calcification or pathological biomineralization correlates with morbidity and mortality from cardiovascular diseases. Aortas with atherosclerotic lesions and biomineralization were selected for the study. Thirty samples of mineralized abdominal aortas (group M) were examined by histology. Depending on the calcifications size, samples were separated into group M1 (macroscopic calcifications) and M2 (microscopic calcifications). Each group consists of 15 samples. Calcification 2 mm or less were considered as microscopic, >2 mm—macroscopic. Thirty samples of aortic tissue without biomineralization (group C) were used as a control group. Aortic tissue was examined by macroscopic description, histology, histochemistry, immunohistochemistry (IHC), scanning electron microscopy (SEM) with microanalysis, and transmission electron microscopy (TEM). The results of IHC showed the involvement of OPN in the formation and development of pathological biomineralization, but the obvious role of OPN in the differentiation of macro- and microcalcifications of atherosclerotic aorta was not revealed. SEM with X-ray microanalysis confirmed that the biomineral part of the aortic samples of the M1 group consisted mainly of apatites, which correspond to previous studies. The Ca/P ratio was less in the M2 group than in the M1 group. It means that microcalcifications can be formed by more defective (immature) hydroxyapatite.

Cyprinid fishes have one of the simplest types of gastrointestinal tract among vertebrates. Those fish species do not possess a true stomach that is replaced by a simple dilatation at the anterior part of the intestine called the intestinal bulb. Twenty adult specimens of grass carp were used in the present study to identify the cellular components as well as the immunohistochemical and surface architectural characteristics of the intestinal bulb. The mucosa of the intestinal bulb shows numerous, deep longitudinal folds arranged in zigzagging-like patterns. The epithelium is composed mainly of absorptive columnar cells covered by microvilli and mucous goblet cells. Spindle-shaped enteroendocrine cells and some migratory immune cells such as intraepithelial lymphocytes and rodlet cells could be identified between the absorptive cells. The epithelium also contains many secretory granules and large numbers of vacuoles containing digestive enzymes mostly in the basal part. The immunohistochemistry revealed that CD20-positive B-lymphocytes are immunolocalized mainly in the connective tissue core lamina propria of the mucosal folds. However, CD3-immunopositive T-lymphocytes are highly concentrated in the lamina propria. In addition, intraepithelial T-lymphocytes expressed immunopositivity to CD3. The current study presented many types of immune cells and suggests their essential immunological role for the intestinal blub.

We studied the fine histological structures of pecten oculi of the Eurasian tree sparrow using various microscopy techniques. The pecten of the tree sparrow was found to be of a pleated type comprising of pleats, bridges, and base. The light microscopic study revealed further that the pleats consist of capillaries of varying sizes, blood vessels, and numerous pigmented cells that give them a black color. Histochemical studies of pecten showed a large deposition of lipid droplets, which were more abundant in the basal area. The transmission electron microscopy displayed capillaries and blood vessels that remain surrounded by a thick fibrous basal membrane. They are formed of endothelial cells having a large lumen and abluminal area with microfolds. Interstitial spaces were found filled with rounded melanocytes, electron-dense pigment granules, and mitochondria. Observations under the scanning electron microscope revealed the presence of a dense vascular network of capillaries and vessels. In addition, large hyalocytes were also observed on the surface of the pleats. The above observations suggest that the histological structure of the pecten of the tree sparrow resembles those present in the pecten of other diurnal birds. However, further investigation is required to ascertain its functional role in birds.