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The aim of this study was to describe microcirculation in the human digit, focusing on the vascular patterns of its cutaneous and subcutaneous areas. We injected a functional supranumerary human thumb (Wassel type IV) with a low-viscosity acrylic resin through its digital artery. The tissues around the vessels were then digested in hot alkali and the resulting casts treated for scanning electron microscopy. We concentrated on six different areas: the palmar and dorsal side of the skin, the eponychium, the perionychium, the nail bed and the nail root. On the palmar side, many vascular villi were evident: these capillaries followed the arrangement of the fingerprint lines, whereas on the dorsal side they were scattered irregularly inside the dermal papillae. In the hypodermal layer of the palmar area, vascular supports of sweat glands and many arteriovenous anastomoses were visible, along with glomerularshaped vessels involved in thermic regulation and tactile function. In the eponychium and perionychium, the vascular villi followed the direction of nail growth. In the face of the eponychium in contact with the nail, a wide-mesh net of capillaries was evident. In the nail bed, the vessels were arranged in many longitudinal trabeculae parallel to the major axis of the digit. In the root of the nail, we found many columnar vessels characterized by multiple angiogenic buttons on their surface.

Microbial chitinases are gaining interest as promising candidates for controlling plant pests. These enzymes can be used directly as biocontrol agents as well as in combination with chemical pesticides or other biopesticides, reducing their environmental impact and/or enhancing their efficacy. Chitinolytic enzymes can target two different structures in insects: the cuticle and the peritrophic matrix (PM). PM, formed by chitin fibrils connected to glycoproteins and proteoglycans, represents a physical barrier that plays an essential role in midgut physiology and insect digestion, and protects the absorptive midgut epithelium from food abrasion or pathogen infections. In this paper, we investigate how two recently discovered metagenome-sourced chitinases (Chi18H8 and 53D1) affect, in vitro and in vivo , the PM integrity of Bombyx mori , a model system among Lepidoptera. The two chitinases were produced in Escherichia coli or, alternatively, in the unconventional – but more environmentally acceptable – Streptomyces coelicolor . Although both the proteins dramatically altered the structure of B. mori PM in vitro , when administered orally only 53D1 caused adverse and marked effects on larval growth and development, inducing mortality and reducing pupal weight. These in vivo results demonstrate that 53D1 is a promising candidate as insecticide protein.

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The ‘fate’ of growth plate hypertrophic chondrocytes has been long debated with two opposing theories: cell apoptosis or survival with transformation into osteogenic cells. This study was carried out on the proximal tibial growth plate of rabbits using light microscopy, scanning and transmission electron microscopy. We focused particularly on the orientation of the specimens included in order to define the mineral deposition and the vascular invasion lines and obtain histological and ultrastructural images at the corresponding height of the plate. Chondrocyte morphology transformation through the maturation process (characterized by vesicles and then large cytoplasmic lacunae before condensation, fragmentation and disappearance of the nuclear chromatin) did not correspond to that observed in the ‘in vitro’ apoptosis models. These findings rather suggested the passage of free water from the cartilage matrix into a still live cell (swelling). The level of these changes suggested a close relationship with the mineral deposition line. Furthermore, the study provided evidence that the metaphyseal capillaries could advance inside the columns of stacked hypertrophic chondrocytes (delimited by the intercolumnar septa) without the need for calcified matrix resorption because the thin transverse septa between the stacked chondrocyte (below the mineral deposition line) were not calcified. The zonal distribution of cell types (hypertrophic chondrocytes, osteoblasts, osteoclasts and macrophages) did not reveal osteoclasts or chondroclasts at this level. Morphological and morphometric analysis recorded globular masses of an amorphous, necrotic material in a zone 0–70 μm below the vascular invasion line occasionally surrounded by a membrane (indicated as ‘hypertrophic chondrocyte ghosts’). These masses and the same material not bound by a membrane were surrounded by a large number of macrophages and other blood cell precursors, suggesting this could be the cause of macrophage recall and activation. The most recent hypotheses based on genetic and lineage tracing studies stating that hypertrophic chondrocytes can survive and transform into osteoblasts and osteocytes (trans‐differentiation) were not confirmed by the ultrastructural morphology or by the zonal comparative counting and distribution of cell types below the vascular invasion line.