The face number, the volume, and the surface area (boundary area) of grains are measured in recrystallized ␣-iron by serial sectioning coupled with quantitative microstructural analysis on twodimensional (2-D) sections. The sampling volume contained approximately 1000 grains whose mean grain size was ϳ15 m. The grain volume distribution decreased monotonously with increasing grain volume, whereas the surface area had a peak around one-half of the average. The distribution of the sphere equivalent radii significantly deviated from the log-normal distribution and distributions predicted from mean field theories. The peak and the mean of the face number distribution were f ϭ 11 and 12.1, respectively. The linear relationship between the face number of a central grain and the mean face number of surrounding grains, known as the Aboav-Weaire law, was observed in three dimensions. The mean radius of f-faced grains was not proportional to the face number (perimeter law in 3-D), but appeared to be related by a curve convex upward.

The composition of muscles by myofiber type is associated with their locomotory or postural functions. In the present study the composition of the hip and thigh musculature of sheep by myofiber types and the differences in their distribution were examined. Myofibers were classified into type I, IIA, and IIB myofibers by differences in myosin ATPase and NADH tetrazolium reductase (NADH-TR) activity. The vastus intermedius muscle consisted only of type I myofibers, which exhibit weak alkali-stable myosin ATPase and strong NADH-TR activity. The gluteus accessorius and profundus muscles had more than 50% type I myofibers. The other muscles had less than 50% type I myofibers as a whole. Type I myofibers were concentrated in the deep portions of the gluteus and quadriceps femoris muscles, which extend the hip and stifle joints, and of the pectineus muscle. They were scattered evenly in the caudally situated locomotory muscles in the thigh. Type IIA myofibers, characterized by strong alkali-stable myosin ATPase and NADH-TR activity, showed little difference in distribution in the hip and thigh muscles. Type IIB myofibers, characterized by strong alkali-stable myosin ATPase and weak NADH-TR activity, were distributed more in the cranial, caudolateral, and caudomedial portions than in the middle portions of the thigh. The distribution of type IIB myofibers is suited to powerful flexion and extension of the thigh and leg. In the hip and thigh musculature, it appears that type I myofibers are effectively distributed to maintain a standing posture without diminishing the propulsive force of the hindlimb.

The conversion of myofiber types was studied in the masseter, trapezius, longissimus, rectus femoris and vastus intermedius muscles of pigs at birth and 2, 4, 8 and 16 weeks of age. The histochemical reaction for ATPase was used to classify myofibers as type I (acid-stable, alkali-labile) or type II (alkali-stable, acid labile). Type II myofibers were divided further into categories IIA and IIB. Subtypes SM, SS and MS were intermediate to types I and II and were classified on the basis of pH sensitivity of the ATPase reaction. In the longissimus, rectus femoris and masseter muscles, the proportion of type II myofibers decreased and the proportion of type I myofibers increased from birth to 8 weeks of age, and little change occurred thereafter. These three muscles had more type II than type I myofibers, regardless of age. At birth the trapezius and vastus intermedius muscles both and more type II than type I myofibers, but during development, the proportion of type I myofibers increased greatly while that of type II decreased markedly. At 16 weeks, the trapezius had about equal proportions of type II and type l myofibers, but the vastus intermedius had a much higher proportion of type I than type II myofibers. A flow diagram was developed to illustrate the proposed conversion of type II to type I myofibers via the intermediate stages identified as subtypes MS, SS and SM. Development of the type I grouped pattern and the association of myofiber proportions with functions in the masseter muscle are discussed.

YH529, [1‐hydroxy‐2‐(imidazo [1,2‐a] pyridin‐3‐yl) ethylidene]‐bisphosphonic acid monohydrate, is a newly developed third‐generation bisphosphonate with a potent inhibitory activity toward osteoclastic bone resorption. The primary cellular mechanism of osteolysis associated with metastatic cancer is osteoclast‐mediated. It is likely that bisphosphonates would be efficacious in this situation. In the present study, we examined the effect of YH529 in a nude mice bone metastasis model, in which the intracardiac injection of a human breast cancer cell line, MDA‐MB‐231(MDA‐231), leads to osteolytic bone metastases. To examine whether YH529 would prevent such bone metastasis, we administered YH529 s.c. to nude mice simultaneously with cancer cell inoculation through the entire experimental period (protocol 1) or performed short‐term prophylactic administration before inoculation of the MDA‐231 cells (protocol 2). In addition, to examine the possible therapeutic effects of the drug on established bone metastases, we injected YH529 after radiographically small but distinct osteolytic bone metastases had been detected (protocol 3). In all protocols, YH529 (2 μg/mouse/day) markedly inhibited bone metastases as well as the progression of established metastatic foci that were quantified on the radiographs. Histological examination and histomorphometrical analysis revealed that YH529 markedly reduced the number of osteoclasts and the size of the tumor at the metastatic bone sites. Our results suggest that YH529 may suppress metastasis formation and tumor growth in bone through inhibition of osteoclastic bone resorption. Int. J. Cancer 77:279–285, 1998.© 1998 Wiley‐Liss, Inc.