Spatial growth and pattern formation in the small intestine microvascular bed from larval to adult Xenopus laevis: a scanning electron microscope study of microvascular corrosion casts

摘要: The microvascular anatomy of the small intestine metamorphosing tadpoles South African Clawed Toad, Xenopus laevis (Daudin) is studied from developmental stages 55 to 65 and in adults by scanning electron microscopy (SEM) vascular corrosion casts (VCCs) light microscopy. Up stage 62, VCCs reveal a dense two-dimensional network ensheating intestinal tube, whose proximal portion forms clockwise spiralling outer its distal an anti-clockwise inner coil. Vessels impose flat run circularly slightly obliquely. Locally, capillary plexus with “holes” indicating ongoing intussusceptive growth (IMG) vessel maturation, are present. typhlosole, invagination along intestine, reveals bed locally IMG. 62/63 for first time three-dimensional longitudinal folds varying size heights greatly enlarging luminal exchange area tube. From onwards, undulate and, though smaller less mature as indicated presence wider, sinus-like vessels interposed between, closely resemble present adult Xenopus. Our data suggest that maturation pattern X. takes place successively after 62–63, during this period preferentially intussusception.