RESUMEN
A special collision unit was used in the experiment by which the distal ends of the fore legs of young rabbits were struck repeatedly on the right aspect. In another group of young rabbits, deep branches of the artery of the right fore legs were ligated and severed. X-Ray examination was made before the two groups of rabbits were killed.Roentgenogram demonstrated: Growth plate of the right fore leg showed wave-like growth, thickened or thinned in the collision group; no difference showed between 2 fore legs in vessel group.Histological demonstrations1. Collision group: 1) Chondrocytcs of articular surface decreased, degenerated and disappeared. 2) Trabecula of the cpiphysis and metaphysis atrophied; osteoblasts and ostcocytcs decreased and degenerated. 3) Growth plate thickened, some arranged wave-like; chondrocytes increased and degenerated. 4) Fibrous tissues and cartilage increased in the mctaphysis. 5) Perichondral ring thickened.2. Vessel group: Similar to the collision group except fibrous and cartilage proliferation in the epiphysis and no arrangement disorder in the growth plate.
RESUMEN
Five young rabbits were divided into 5 groups (2, 4, 6, 8 and 12 week), one rabbit in each group.A special collision unit was used in the experiment by which the distal ends of the right fore legs of rabbits were struck repeatedly. Altrastructure changes of chondrocyte at the epiphyseal plate in the distal endof radius were observed in H-500 electron microscope. In two and four week groups, organaelles swelling was found such as rough endoplasmic reticulum andmitochondria, especially mitochondria swelling which showed different shapes like sausagge and racket.Space around nucleus increased, nucleus shape changed, myeline structure in the mitochondria and chroma- tin margination in the nucleus were found in the six and eight week groups. Altrastructure changes weremore serious in the eight and twelve week groups than other groups. Necrosis of chondrocyte was appearedsuch as part organaelles dissolved or disappeared, nucleus brokeu aud nucleus memberane disappeared. The results showed in altrastructure pathology that chronic collision injury can cause not only degeneration of chondrocyte in the pressure epiphyseal plate but necrosis of chondrocyte as well. It concluses that chondrocyte necrosis is related to local ischemia resulted from chronic collision injury.
RESUMEN
Ten young rabbits were divied into 5 groups (2,4,8,12 and 16 weeks), two in each group Perichondrium around the epiphyseal plate at the distal end of the radius of right fore-leg was partially excised to observe its effect on the growth of the long bone, In all groups except the 2-week group, growth at the distal end of the radius was observed to have slowed clown markedly (P