[Effect of human growth hormone on mandibular condyle growth of the rat].

The purpose of the present work was to study the effects of human growth hormone (GH) to the growth of mandibular condyle after hypophysectomy in the growing rats. Ninety female rats of the Wistar SLC strain weighing approximately 60 grams fed on a commercial laboratory chow were divided into three groups of 30 animals each. Except one group (normal control) they were hypophysectomized at 3 weeks after birth, and 10 of the operated groups respectively received intraperitoneally the growth hormone (GH group) in a single dose of 160 mIU per 100 g weight. The remaining one operated group was untreated control (hypophysectomized group). The animals were sacrificed 2 weeks after injection and the heads were fixed in 10% formalin solution for 5 days. Half sides of the heads were decalcified, and the other halves were not decalcified. The blocks were the embedded in paraffin and Big-GMA, and the widest point of the processes were cut in sections, stained with hematoxylin-eosin and Villanueva-Goldner Stein. The results were as follows: 1. Body Weight All of the animals averaged 60 grams initially. At the end of the experiment, the control group averaged 190 grams and the body weight was markedly increased. The hypophysectomized group averaged 63 grams. As compared with the control, this group did not show much increase in the body weight. However, the GH group averaged 110 grams and began to gain weight, but the body weight did not reach to the level of the control. 2. Histopathological Findings 1) In the normal control, the head of the condylar process was large, the articular zone was thick, the cartilage plate wide, and the cells were large in size and number and arranged regularly. Bone tissue adjacent to the erosion zone consisted of fine complicated trabeculae which were joined each other. The osteoblasts and osteoclasts were large in size and number and appeared very active. 2) In the hypophysectomized group, the head of the process was small showing atrophy, and the articular zone was similar to the control. The embryonic zone was thin and cells were small and spindle form in shape as compared with the control. The hypertrophic zone showed extensive atrophy. The cell decreased in size and number and were arranged irregularly.(ABSTRACT TRUNCATED AT 400 WORDS)