title: Histomorphometric identification of carbonic anhydrase in fetal rat bone embedded in glycolmethacrylate.
abstract: Carbonic anhydrase was identified in bone-resorbing cells present in sections of fetal rat femur embedded in glycolmethacrylate. Using a slight modification of the Hansson's histochemical method, we demonstrated that most chondroclasts (91.8-95.4%) and osteoclasts (95.1-96.3%) display a positive histochemical reaction for carbonic anhydrase. This staining was consistently inhibited in the presence of very low concentrations (10(-6), 10(-7) M) of the specific inhibitor acetazolamide. The number of chondroclasts reacting for carbonic anhydrase was identical to the number of acid phosphatase-stained chondroclasts determined on adjacent sections. A large majority of osteoclasts (96.3%) stained for carbonic anhydrase and for acid phosphatase (97.2%), with more osteoclasts reacting for the latter enzyme than the former (76.8 +/- 8.5 (SD) vs 85.3 +/- 9.2 cells/mm2 of endosteal bone; p less than 0.01). The observation that acetazolamide at a concentration as low as 10(-7) M inhibited Hansson's reaction, together with our histomorphometric results, validates the use of histochemical staining for carbonic anhydrase to evaluate activity of bone-resorbing cells identified in plastic-embedded fetal bone tissue.
mesh_terms: D000179:Acrylates; D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D001842:Bone and Bones / Q000196:embryology* / Q000201:enzymology; D002256:Carbonic Anhydrases / Q000032:analysis*; D005260:Female; D005404:Fixatives; D006651:Histocytochemistry; D008689:Methacrylates; D010010:Osteoclasts / Q000201:enzymology; D011247:Pregnancy; D051381:Rats
chemical_list: D000179:Acrylates; D005404:Fixatives; D008689:Methacrylates; C005044:hydroxyethyl methacrylate; D000469:Alkaline Phosphatase; D002256:Carbonic Anhydrases