A defect of 4 mm in length was made in both radii of 140 adult male rabbits underanesthetic and antiseptic conditions. Their adrenal glands were taken at different timeintervals during the healing of the bone defect. They were studied together with thosefrom 10 normal untreated controls with various histological and histochemical techniques. There is no distinct histological changes found in the cortex, except the presence of"compact cells" in the fascicular zone and dilatation of cortical blood sinusoids on thethird day. During the healing of the fracture the fascicular and reticular zones are the chiefsites in the adrenal cortex where histochemical changes are involved. During the earlystage, 1--7 days after the fracture, they show a decrease in sudanophilia (Sudan blackB), and an increase in the naphthoic acid hydrazide reaction (Ashbel and Seligman). The reaction of alpha-ketol groups of corticoids (Khanolkar et al.) shows varying degreesof decrease in intensity, whereas the plasmal reaction (Hayes) has a tendency to in-crease in intensity. Ascorbic acid (Bacchus), acid and alkaline phosphatases (Gomori)and ribonucleic acid (Kurnick) all show an increase in reaction. All these changes re-turn to normal later during the period of 10--14 days after the fracture. Basing on the above findings, it is concluded that the adrenal cortex is at an activefunctional state during the early period of the healing process.

Open skin wounds were made in 28 Wistar rats, and the changes of the connective tissue cells were observed by electron microscopy during wound healing. The fibroblasts and macrophages were increased in the early stage, later on the fibroblasts might be transformed into myofibroblasts which became preponderant cells in the wound gradually and led to wound contraction and scar formation. The intercellular substances were phagocytosed by fibroclasts simultaneously. The mast cells were closely apposed to the fibroblasts or myofibroblasts and represented active functions, such as degranulation. Considerably they released the granule contents to the extracellular space and effected the other cells functions. It shows that the cells mentioned above interplay and take part in the wound healing.