Irisin Has a Protective Role against Osteoporosis in Ovariectomized Rats

Figure 1

Representative photomicrographs from the longitudinal sections of distal femoral diaphysis revealing the effects of ovariectomy and irisin hormone on the bone structure of rats. The control groups (G I and G II) show the typical bone architecture, outer cortical bone (CB) covered by smooth outer periosteum (P) and lined by smooth endosteum (E). A distinct basophilic cement line (arrow) demarcating between the newly formed bone matrix and the older bone. In contrast, the ovariectomized control rats (G III) reveals loss of typical bone architecture with an irregular periosteal surface (P), an apparent increase in the number of resorbed bone cavities (curved arrow), some osteocytes (yellow star), and numerous osteoclasts (red star), while the ovariectomized rats treated with irisin hormone (G IV) exhibits outer cortical bone (CB) covered by smooth periosteum (P) and inner endosteum (E) containing bone marrow (BM) with numerous osteocytes (yellow star), few osteoclasts (red star), and basophilic cement lines (arrow). In all groups (G I, G II, G III, and G IV), the upper panel is stained with H&E; 100x, and the lower panel is stained with H&E; 400x, ). The histogram (H) of Figure 1 represents the statistical analysis of the number of osteocytes, osteoclasts, and resorbed bone cavities/10 HPF of bone tissue. denotes a significant difference between G IV versus G II and G III.