Studies on dairy cows' bone structure

Bone routine morphology and factors able to influence bone structure in dairy cows were investigated. Humerus bone in 5-6 years lactating cows were examined after their compulsory slaughtering. The Cutting-Grinding Technique was used for dissection of bone. Also mineral density test was used for cows' bones. Growth factors - BMP2/4, FGFR, were used to detect cell growth and cellular differentiation by immunohistochemistry (IMH). TUNEL method was performed to detect cell death and for matrix degradation we used MMP2 and MMP9 IMH detection. Bone showed thin trabecules with variable number of osteocytes from 20.30±3.79 to 54.30±5.66 per mm2.
Osteones also presented different diameter - from 0.0668±0.0183 to 0.1596±0.0285 mm. Intensive proliferation of connective tissue and small capillaries were seen in osteon channels. Regions with granular, optically intensively stained basophilic substance were observed regionally in bone with density from 2206.45±714 to 3017.94±744 g cm2. Fragments of articular cartilage were not changed in routine histological sections. Few BMP2/4-containing cells were detected in all chondrocytes of articular cartilage in all animals and in main part of bone of cows. Numerous to abundance of chondrocytes expressed FGFR1 in articular cartilage, but only few osteocytes of spongy bone contained these receptors. Total apoptosis affected mainly chondrocytes. Both matrix metalloproteinases mainly degraded cartilage. Healthy dairy cows bone demonstrated various number and diameter osteocytes of osteones, different density, proliferation of connective tissue and small capillaries in osteon channels that proves regional osteoporosis. BMPs were expressed in articular cartilage. FGFR, apoptosis and MMP more affected the articular cartilage.