Comparative Study Of Osteological Microstructure In Mordon Birds

The study of osteohistology in Aves can help make accurate analysis of growth, development,physiology and so on.The cross section of typical osteological microstructure of long bones in modern birds is stratified into three main regions:outer circumferential lamellae, inner circumferential lamellae and Haversian lamellae.Birds living in different environmental conditions differentiate in Osteological microstructure.Environmental factors such as mechanical stress,food supply,temperature,day long will affect osseous tissue.Slices of humerus and femurs are made from 45 species of 15 orders in extant birds. The slices were described,compared,and measured.The results are as follows:(1) There are mostly four types of osseous tissue in birds:fibrolamellar bone,the parallel-fibred compacta, fibro lamellar bone and lamellar bone.For most birds,the osteohistology belong to fibrolamellar bone.Different types of osteohistology show that humerus and femur may not development synchronously.(2)Many secondary osteons are found in humerus or femur of some large birds such as Crossoptilon auritum,Tetraogallus himalayensis,Syrmaticus reevesii, Aegypius monachus,but not in small birds.The number of secondary osteons may relate to the capability of weight bearing in birds.(3) Different birds have different tissue structure of bone girders:the main part of girders is either inner circumferential lamellae or Haversian lamellae. (4)The bone walls protrude in some slices.Stimulating caused by force,weight bearing and so on,may affect the reconstruction of Haversian system.