Effect of ovariectomy on longitudinal bone growth in the rat.

The effect of ovariectomy on longitudinal bone growth was studied in growing rats. The operation was performed at ages 20, 40, and 60 days. Sham operations were made at age 40 days. At different postoperative intervals, the growth rate was determined with the tetracycline technique, and the width of the growth plate was registered. After a slight initial retardation, the growth rate after ovariectomy was significantly greater than in normal rats during a 40-60 day period. During the same period, the growth plate was wider. The increase in growth rate was greater and more rapid if ovariectomy was performed in older animals. The results indicate that ovariectomy increases longitudinal bone growth and that longitudinal bone growth and skeletal maturation depend less on ovarial function in young animals than that in more mature animals.