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Table 1 Major histological characteristics at each time-point in ST graft

From: Histological changes of semitendinosus autograft after anterior cruciate ligament reconstruction in an immature rabbit model

  1 week 4 weeks 6 weeks 8 weeks 12 weeks 24 weeks 48 weeks
Necrosis Focal cell-free areas with small necrosis Cell-free areas with poor necrosis Gradually disappeares No necrosis sign
Neovascularization No vessel Poor and located on the grafts periphery Vessel located in the periphery of the graft and runned parallel to the collagen fiber bundles in the septa Vessel located from periphery to central area Normal vascularity
Organization of the collagen fibers ST tendon characteristics Disorganized collagenous fibers Initial longitudinal arrangement Collagen fibers aligned in parallel with the new capillaries and with the fibroblastic cells Loss of regular collagen orientation and crimp pattern Slight separation with increased waviness of fibers
Shift of the diameter of the collagen fibrils, from large to small Unimodal appearance of collagen fibrils
Reduction of collagen type I fibrils Failure restauration of collagen orientation to normality
Increase of collagen type III synthesis  
Cellularity Inflammatory cell population Aligned longitudinally, more rounded fibroblastic cells with large nuclei and abundant cytoplasm Highly differentiated fibroblastic cells Normal cellularity
Disorganized and randomly arranged fusiform-like fibroblastic cells with plump nuclei Gradual disappearance of the typical inflammatory cell population Fibrocyte have different characteristics from fibroblastic cells