Latvijas Lauksaimniecības universitātes raksti nr. 18 (313) , 2007 ...

M. Pilmane et al. Investigation of Cow Bone Tissue StructureInvestigation of Cow Bone Tissue StructureGovju kaulaudu struktūras pētījumiMara PilmaneInstitute of Anatomy and Anthropology, Riga Stradins University, e-mail: pilmane@latnet.lvRīgas Stradiņa universitātes Anatomijas un Antropoloģijas institūts, e-pasts: pilmane@latnet.lvInese Zitare, Aleksandrs JemeljanovsResearch Institute of Biotechnology and Veterinary Medicine ”Sigra” of LLU, e-mail: sigra@lis.lvLLU Biotehnoloģijas un veterinārmedicīnas zinātniskais institūts „Sigra”, e-pasts: sigra@lis.lvAbstract. Bone routine morphology and factors able to influence bone structure in dairy cows were investigated.Humerus bone in 5-6 years old lactating cows was examined after compulsory slaughtering of cows. TheCutting-Grinding Technique for Hard Tissue was used for dissection of bone. Mineral density test was usedfor cow bone investigation too. Growth factors BMP2/4 and FGFR were used to detect cell growth and cellulardifferentiation by immunohistochemistry (IMH). TUNEL method was performed to detect cell death. MMP2and MMP9 IMH detection was used for matrix degradation. Bone showed thin trabecules with the numberof osteocytes varying from 20.30±3.79 to 54.30±5.66 per mm 2 . Osteones also presented different diameter –from 0.0668±0.0183 to 0.1596±0.0285 mm. Intensive proliferation of connective tissue and small capillarieswas seen in osteon channels. Regions with granular, optically intensively stained basophilic substance wereobserved here and there in bone with density from 2206.45±714 to 3017.94±744 g cm -2 . Fragments of articularcartilage seemed not changed in routine histological sections. Few BMP2/4-containing cells were detected inall chondrocytes of articular cartilage in all animals and in main part of bone of cows. Numerous to abundanceof chondrocytes expressed FGFR1 in articular cartilage, but only few osteocytes of spongy bone containedthese receptors. Total apoptosis affected mainly chondrocytes. Both matrix metalloproteinases degraded thecartilage. Bone of healthy dairy cows demonstrated various number of osteocytes and diameter of osteones,and different bone density. Proliferation of connective tissue and small capillaries in osteon channels indicatedregional osteoporosis. BMPs were expressed in articular cartilage. The articular cartilage is more affected byapoptosis and FGFR and MMP expression.Key words: growth factors, apoptosis, bone density, long bones, healthy cows.IntroductionBone – specialized and mineralized supportivetissue that together with cartilages makes the skeletalsystem. The system is essential to life and has threemain functions: mechanical function – to give supportand site for muscle attachment, barrier function – tolimit and defend internal organs, and metabolicfunction – to develop source for calcium and phosphatethat insure maintenance of serum homeostasis.Bone tissue has the capacity of postnatal selfreconstruction.The process of bone turnover in animalsoccurs through 2 different processes: modelationof bone and remodelation of bone (Buckwalter etal., 1996). Modelation provides bone growth wherebone formation and bone reabsorbtion are connectedprocesses. Remodelation involves the sequentialremovement and replacement of bone at discretesites by the actions of osteoclasts and osteoblaststhat comprise the bone multi-cellular unit (Kahn etal., 1983; Frost, 1992). Balanced bone reabsorbtionand bone formation provide constant bone mass.However, efficiencies of bone reabsorbtion and bonereplacement may change with animal age and duringmetabolic diseases.The relation between Ca and P is a constant valuein the cow’s organism. A total of 98% of the calciumin cow’s body is stored within the skeleton and itshomeostasis is maintained by parathyroid hormone,vitamin D 3, and calcitonin. At homeostasis, Caturnover results in equal flux in and out of skeleton.Maintaining the Ca and P pool constant during lactationis a formidable challenge to dairy cows (Horst et al.,1997; Ekelund et al., 2003). Calcium and phosphorusmetabolism and bone turnover has been studiedmuch more in metabolic bone diseases and mineralmetabolism disturbances and during milk fever ofhighly producing cows. The last one is metaboliccondition that occurs in dairy cattle when the intakeof nutrients is inadequate to meet the productiondemands of the cow. This disorder is described toshow changes of the bone system in animals. Thecommon features are the reduced strength of bone,the tendency to form exostoses, bone atrophy, and adeficient calcification (Shupe et al., 1963).Different animals and different methods havebeen used for investigation of bone quality. So,ultrasound was found as a tool for assessment ofbone quality in the horse (Jeffcott and McCartney,LLU Raksti 18 (313), 2007; 51-5751