Fluorescent cell tracer dye permits real-time assessment of re-epithelialization in a serum-free ex vivo human skin wound assay

YesEx vivo wounded human skin organ culture is an invaluable tool for translationally relevant preclinical wound healing research. However, studies incorporating this system are still underutilized within the field because of the low throughput of histological analysis required for downstream assessment. In this study, we use intravital fluorescent dye to lineage trace epidermal cells, demonstrating that wound re‐epithelialization of human ex vivo wounds occurs consistent with an extending shield mechanism of collective migration. Moreover, we also report a relatively simple method to investigate global epithelial closure of explants in culture using daily fluorescent dye treatment and en face imaging. This study is the first to quantify healing of ex vivo wounds in a longitudinal manner, providing global assessments for re‐epithelialization and tissue contraction. We show that this approach can identify alterations to healing with a known healing promoter. This methodological study highlights the utility of human ex vivo wounds in enhancing our understanding of mechanisms of human skin repair and in evaluating novel therapies to improve healing outcome.University of Manchester Strategic Fund; Wellcome Trust; BBSRC; Ministry of Higher Education, Malaysia Universiti; Sains Malaysi

Maturation of the gastric microvasculature in Xenopus laevis (Lissamphibia, Anura) occurs at the transition from the herbivorous to the carnivorous lifestyle, predominantly by intussuceptive microvascular growth (IMG): a scanning electron microscope study of microvascular corrosion casts and correlative light microscopy

The microvascular bed of the stomach of Xenopus laevis and the changes it undergoes when the herbivorous tadpole becomes a carnivorous adult were studied by scanning electron microscopy of vascular corrosion casts and light microscopy of stained tissue sections. In tadpoles an upper and a lower gastric artery supplied, and upper, middle and lower medial and lateral gastric veins drained the vertically extending stomach. During metamorphosis, the stomach gained a horizontal cranio-caudal extension and vessels accordingly become dorsal and ventral gastric arteries, and anterior, middle and posterior gastric veins, respectively. Up to stage 64 (late climax) mucosal capillaries formed a polygonal network of wide immature-looking capillaries ensheathing gastric glands in a basket-like manner. From stage 64 onwards, blood vessels of the stomach appeared mature, revealed a clear hierarchy and were correlated closely with the histomorphology of the stomach, which had also gained the adult pattern. Within the gastric mucosa, ascending arterioles branched in a fountain-like pattern into wide subepithelial capillaries establishing a centripetal blood flow along the gastric glands, which makes an ultrashort control loop of glandular cells within the branched tubular gastric glands very unlikely. Formation of the stomach external muscular layer started at stage 57 when smooth muscle cells locally formed a single longitudinal and one-to-two single circular layers. Abundant signs of intussusceptive microvascular growth and rare vascular sprouts in vascular corrosion casts indicated that the larval-to-adult microvascular pattern formation of the stomach of Xenopus laevis Daudin occurs predominantly by non-sprouting angiogenesis

Nervous Organization of the Pineal Complex in Lower Vertebrates

Volume: 6Start Page: 817End Page: 83

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