NUCLEAR PROFILE AREA OF OSTEOBLASTS IN NORMAL, OSTEOPOROTIC, AND FLUORIDE-TREATED SUBJECTS

Osteoblasts undergo changes both in shape (progressive flattening) and function (progressive decline in matrix synthesis) during their life span. Nuclear volume, apart from changing systematically during their cell cycle, is believed to be a general index of cell vigor. According ly, we measured the nuclear profile area of osteoblasts classified as pre (Group I), cuboidal (Group II), intermediate (Group III), and term inal (Group IV) in iliac cancellous bone in 6 premenopausal normals, m ean age in years (SD) 40.2 (4.8), 5 postmenopausal normals, age 65.8 ( 2.4), 15 postmenopausal osteoporotics, age 65.3 (4.9), 5 patients with fluoride-induced osteomalacia, age 69.2 (5.0), and two patients with endemic fluorosis, age 70.5 (5.5). A total number of 4,085 osteoblast nuclei were examined and measured. In each group there was a systemati c decline in nuclear profile area through stages I-IV, corresponding t o an average decline in nuclear volume of greater than 90%. The major difference among groups was that in type II (cuboidal) osteoblasts, nu clear profile area was significantly greater in premenopausal normals than in the other four groups, which did not differ significantly. The effect seems to be related to age, rather than to disease or treatmen t. The functional significance of this age-related morphologic change remains to be determined, but it may be related to the decline in appo sition rate with age.