This is a scanning and transmission electron microscopic study of the changes produced by small doses of calcitonin (0.15 mU/g body weight) in the lining cells and their microenvironment at the endosteal surfaces of the tibia of neonate rats. The techniques used included "freeze substitution" preparation, staining with lead acetate, and with lanthanum added to the fixative. Rats were sacrificed 5, 15, and 30 minutes after subcutaneous injection of salmon calcitonin. The following observations were made; within 5 minutes following calcitonin injection, the response of the endosteal lining cells included increased numbers of microvilli and surface blebs. Cell contraction was apparent, including an irregular appearance of the plasma membrane and enlarged intercellular channel size, though cell-to-cell contact still occurred. By 15 minutes, following hormone injection, the cells were returning to normal morphology and were in close contact with each other. Calcitonin caused a marked accumulation of lanthanum around osteocytes and in bone fluid adjacent to lining cells. The lanthanum was found in large aggregates and appeared to "clump." Following "freeze substiuttion" preparation, the edge of the osteoid was bordered by what appeared to be mineral aggregates. We conclude that bone lining cells and osteocytes respond rapidly to low doses of calcitonin, thereby suggesting that they play a role in the physiological action of the hormone. This function includes a modification of the fluid microenvironment of these cells, possibly providing a site for temporary storage of calcium.

Animals↗

PubMedDate not supplied

The development of the spinal deformities in osteogenesis imperfecta.

Evaluations were made of the spinal deformities in 22 of 30 patients (osteogenesis imperfecta congenita, eight; osteogenesis imperfecta tarda I, 13; osteogenesis imperfecta tarda II, one) treated at Hamagumi Gakuen Children's Hospital from 1959 to 1980. Seven of the congenital type patients were in the severe curve group (greater than 50 degrees), four of whom showed more than 100 degrees of curvature. The spinal deformities in the congenital type progressed rapidly after five years of age and reached a maximum around 12 years of age. The scoliosis in the tarda type patients developed slowly, but then progressed rapidly after the curve exceeded 50 degrees. The complications of the spinal deformities included disability on ambulation, inactivity in daily living, and possibly respiratory dysfunction. Progression of the spinal curvature should be prevented by functional bracing or surgical treatment before severe complications arise.

Adolescent↗