Eighty-eight Long Evans/Turku rats were used in the study. The effect of the articulatory function on the mandibular condyle was observed histologically during normal growth, when the rat is changing its diet from milk to whole pellets as a part of weaning. Six animals each were killed at the age of 10, 15, 20, 25, 30,35, 40 and 50 days for histological tissue processing. For further information, 30 animals were fed a soft diet (6 animals each were killed at the age of 25 30, 35, 40 and 50 days), and 10 animals were fed hardened pellets (2 animals each were killed at the ages of 25, 30, 35, 40 and 50 days). An even and regular transition from mesenchymal cells via immature chondroblasts into mature chondroblasts and hypertrophied chondrocytes was found at 10,15 and 20 days during normal growth and also at 25, 30, 35, 40 and 50 days when animals were fed a soft diet. This maturing process appeared to be disturbed at the age of 25, 30, 35 and 40 days in the superior aspect of the condyle in animals fed ordinary pellets. The density of the mesenchymal cell layer was decreased, and the amount of intercellular matrix seemed to be elevated in mesenchymal and intermediate cell layers. These features were later manifest deeper in the cartilage as acellular regions and as cell clusters. The changes were similar but more severe when the animals were fed hardened pellets. The thickness of the cartilage was decreased, and chondrocytes appeared small and surrounded by abundant amounts of extracellular matrix in these animals at the age of 50 days. The findings are suggestive of features in the condylar cartilage that have been attributed to the articular cartilage of long bones. They seem to indicate that, while the condylar cartilage is obviously under loading during functioning, the articulatory function may suppress the growth of the condylar cartilage by changing its properties towards those typical of the purely articular cartilage. The functional loading during normal growth is obviously close to the maximum that the mandibular condyle is capable of sustaining.