Scanning electron micrograph of bone biopsy specimens in a normal subject (a) and age- and sex-matched patient with primary hyperparathyroidism (b). The cortices of the hyperparathyroid sample are markedly thinned, but cancellous bone and trabecular connectivity appear to be well preserved. (Magnification × 31.25.) (From Parisien MV, Silverberg SJ, Shane E, et al. Bone disease in primary hyperparathyroidism. Endocrinol Metab Clin North Am, 1990; 19: 19–34.)