Fetal bladder wall regeneration with a collagen biomatrix and histological evaluation of bladder exstrophy in a fetal sheep model.

Contains fulltext : 70288.pdf (publisher's version ) (Closed access)OBJECTIVES: To evaluate histological changes in an animal model for bladder exstrophy and fetal repair of the bladder defect with a molecular-defined dual-layer collagen biomatrix to induce fetal bladder wall regeneration. METHODS: In 12 fetal lambs the abdominal wall and bladder were opened by a midline incision at 79 days' gestation. In 6 of these lambs an uncorrected bladder exstrophy was created by suturing the edges of the opened bladder to the abdominal wall (group 1). The other 6 lambs served as a repair group, where a dual-layer collagen biomatrix was sutured into the bladder wall and the abdominal wall was closed (group 2). A caesarean section was performed at 140 days' gestation, followed by macroscopic and histological examination. RESULTS: Group 1 showed inflammatory and maturational changes in the mucosa, submucosa and detrusor muscle of all the bladders. In group 2, bladder regeneration was observed, with urothelial coverage, ingrowth of fibroblasts and smooth muscle cells, deposition of collagen, neovascularization and nerve fibre formation. This tissue replaced the collagen biomatrix. No structural changes of the bladder were seen in group 2. CONCLUSIONS: The animal model, as in group 1, for bladder exstrophy shows remarkable histological resemblance with the naturally occurring anomaly in humans. This model can be used to develop new methods to salvage or regenerate bladder tissue in bladder exstrophy patients. Fetal bladder wall regeneration with a collagen biomatrix is feasible in this model, resulting in renewed formation of urothelium, blood vessels, nerve fibres, ingrowth of smooth muscle cells and salvage of the native bladder

Changing times, spaces, and faces: tests and implications of adaptive morphological plasticity in the fishes of northern postglacial lakes

The phenotypic diversity exhibited within and among populations of freshwater fishes in postglacial lakes has intrigued biologists for two reasons: (i) their high phenotypic variation and (ii) the apparently recent and rapid divergence of forms. Genetic and ecological studies of these taxa are shedding new light on mechanisms of divergence and species formation. Surprisingly, the roles of phenotypic plasticity in the origins, maintenance, and generation of phenotypic diversity in this system are rarely directly addressed. We synthesize the available literature on morphological plasticity in these fishes and, using a meta-analysis, test for adaptive plasticity. We conclude that (i) morphological plasticity is common in at least six families of northern freshwater fishes, (ii) plastic responses can often be induced by conditions related to littoral and pelagic lake environments, (iii) plasticity often represents adaptive responses to conditions in these habitats, and (iv) that although rarely tested, heritable variation in morphological plasticity is present. The rich amount of phenotypic plasticity has not constrained recent adaptive divergence and species formation in postglacial fishes, and instead plasticity may play a role in the notably high rates of divergence observed in these and other fishes currently undergoing adaptive radiation