Anatomical and histochemical characterization of leaves of Spondias purpurea L.

The Anacardiaceae family has species rich in secondary metabolites. They are widely used in popular medicine. Among them, Spondias purpurea L. stands out for containing several secondary metabolites with important biological activities. To aid in the precise identification of the species, this work aims to perform an anatomical and histochemical characterization of leaves of S. purpurea. Microscope slides containing cross-sections of the petiolule and leaflets, in addition to paradermal sections of the leaflets, were prepared and analyzed in an optical and polarized microscope. Histochemical tests were performed on fresh leaflets. Through microscopic analysis, it was possible to identify the anatomical structures that allow the diagnosis of the studied species, such as petiolule with concave-convex shape, non-glandular and glandular trichomes, druses in phloem; leafletsamphistomatic, with non-glandular trichomes on the adaxial face and glandular trichomes on the abaxial face, midrib with concave-convex shape, two collateral vascular bundles, one layer of palisade parenchyma, druses in phloem and mesophyll. Through histochemistry, the presence of phenolic compounds, alkaloids, tannins, triterpenes, steroids, lipophilic compounds, essential oils, lignin, starch and calcium oxalate crystals were evidenced in the leaflets. The results are important for the quality control of plant material.

Perspective for a New Bioinspired Permanent Adhesive for dry Conditions - Insights in the Glue Producing Japanese art of Defence System of the Oita Salamander Hynobius dunni

Novel medical bioadhesives are proposed to fulfil numerous ideals as being biocompatible, non-toxic, include tissue healing and regeneration characteristics, have high mechanical properties onto different surfaces and other important key features. Mussel-inspired adhesives have provided the basis for many new applications under wet conditions. In contrast, the defence secretion system in amphibians may provide potential for novel fast-curing secretion able to adhere to surfaces under dry conditions. With the microanatomical and histochemical characterization of the endemic Japanese Oita salamander Hynobius dunni details on its anatomical organization, the nature of the chemical composition of both glue-producing glands and its divergence to the other well-characterized species Plethodon shermani are discussed. The study shows that the cutaneous glands of both glue-producing salamanders (H. dunni and P. shermani) exhibit certain morphological and histochemical similarities. Nevertheless, clear differences exist between the two species, especially with regard to the sugar composition of the mucous glands and the pH level of the granular glands. Moreover, the adhesive secretions of H. dunni show a clear reactivity to Arnow staining (indicating the presence of L-DOPA), which is lacking in P. shermani. This is the first indication of the presence of L-DOPA in the adhesive secretions of a terrestrial vertebrate, which has thus far only been found for marine invertebrates, such as mussels and polychaetes.

Histochemical Characterization of the Vestibular Y-Group in Monkey

The Y-group plays an important role in the generation of upward smooth pursuit eye movements and contributes to the adaptive properties of the vertical vestibulo-ocular reflex. Malfunction of this circuitry may cause eye movement disorders, such as downbeat nystagmus. To characterize the neuron populations in the Y-group, we performed immunostainings for cellular proteins related to firing characteristics and transmitters (calretinin, GABA-related proteins and ion channels) in brainstem sections of macaque monkeys that had received tracer injections into the oculomotor nucleus. Two histochemically different populations of premotor neurons were identified: The calretinin-positive population represents the excitatory projection to contralateral upgaze motoneurons, whereas the GABAergic population represents the inhibitory projection to ipsilateral downgaze motoneurons. Both populations receive a strong supply by GABAergic nerve endings most likely originating from floccular Purkinje cells. All premotor neurons express nonphosphorylated neurofilaments and are ensheathed by strong perineuronal nets. In addition, they contain the voltage-gated potassium channels Kv1.1 and Kv3.1b which suggests biophysical similarities to high-activity premotor neurons of vestibular and oculomotor systems. The premotor neurons of Y-group form a homogenous population with histochemical characteristics compatible with fast-firing projection neurons that can also undergo plasticity and contribute to motor learning as found for the adaptation of the vestibulo-ocular reflex in response to visual-vestibular mismatch stimulation. The histochemical characterization of premotor neurons in the Y-group allows the identification of the homologue cell groups in human, including their transmitter inputs and will serve as basis for correlated anatomical-neuropathological studies of clinical cases with downbeat nystagmus.

Morphological and Histochemical Characterization of the Dermal Plates of Pleco (Hypostomus plecostomus)

Studying the dermal skeleton in fish is valuable for phylogenetic specification. The current study describes the detailed structure of the plecostomus dermal skeleton, including its morphogenesis and distribution in the skin. The denticles have a crown and a basal part and are embedded in bony depressions, to which they are attached by denticle ligaments. During denticle morphogenesis, denticle papillae formed from denticle precursor cells align in two cellular layers: an outer ameloblast precursor layer and an inner odontoblast precursor layer. The ameloblast precursors and odontoblast precursors differentiate and secrete enamel and dentine, respectively. We used different histochemical techniques, including Crossmon's trichrome staining, Weigert–Van Gieson staining, periodic acid–Schiff (PAS) staining, combined Alcian blue (AB; pH 2.5)/PAS staining, Weigert–Van Gieson staining, Mallory trichrome staining, and AB staining to distinguish the dentine and denticle ligaments. We used acridine orange to detect lysosome activity during denticle eruption. Transmission electron microscopy was used to detect the denticle ultrastructure, and scanning electron microscopy was used to detect the topographic distributions of different types of dermal tissues in different anatomical regions.