Microarchitectonics and histomorphometric parameters of bone tissue during remodeling

Abstract

The article shows and statistically substantiates thepeculiarities of remodeling and structure of cortical andmedullary bone tissue in two age groups (160- and 225days) of laying hens before and during egg-laying. Theaim of the study was to analyze the structural organization of bone tissue in different states of performance.The material for the study was the ulnae of the forearmof laying hens of two experimental groups. Histological studies: fixed in a 10% solution of neutral formalin,decalcified in Wilenson's fluid, dehydrated in alcoholsof increasing concentration, embedded in paraffin, prepared transverse sections from the middle third of thediaphysis, stained by Frankel, Hart, Malory, hematoxylin and eosin. Microscopy and morphometric studies were performed using an Axiolar plus microscope(Carl Zeiss), photographs were taken and measuredusing a Sigeta MDC-200 video camera (eyepiece x10,lenses x25/0.50, x40/0.65, 100/0.25) integrated with anAxiolar plus personal computer (Carl Zeiss). Statisticalprocessing of digital material was performed by Student's t-test. Changes in the structure of cortical bonetissue during the study period are associated with physiological remodeling. This is evidenced by the presenceof cementing lines of individual osteons, semi-osteonsand Haversian canals with an enlarged diameter. Theabsence or insignificant development of the insertionsystem of the forming bone plates indicates a low rateof physiological remodeling of the compact bone substance. The external general system of plates does notchange the structure. The internal general system ofbone plates is unevenly developed. From 160 to 225days of age, the development and accumulation ofmedullary bone tissue occurs, which is confirmed bya significant increase in the area of trabeculae by 2.8times (P3 = 0.999), a complication of their structureand a decrease in the area of intertrabecular spaces by1.7 times (P2 = 0.99). A significantly higher 3.4-fold(P1 = 0.95) volume of osteoblast nuclei at 160 days indicates their active functional activity - the formationof trabeculae of medullary bone tissue. During the period of 160 days, special attention should be paid to thebalance of the diet of laying hens to ensure the formation of a sufficient amount of high-quality medullarybone tissue. Key words: lamellar bone tissue, cortical, medullary, spongy and compact substance, restructuring,histomorphometry, laying hens.