Shimada A, Asada Y, Oura R, Umemura T
Department of Veterinary Pathology, Faculty of Agriculture, Tottori University, Japan.
J Vet Med Sci. 1991 Dec;53(6):1009-12. doi: 10.1292/jvms.53.1009.
The bone marrow is commonly present in the medullary cavity of long bones in most mammals at birth. In the present study, the persistence of the osseous tissue was examined in the medullary cavities of piglet bones at and after birth. Immediately after birth, medullary cavities of long bones were almost completely filled with the spongy bone. The persisted spongy bone, i.e., medullary bone was prominent in younger pigs but decreased with advance in age. By 90 days of age, the medullary bone almost disappeared to form the extended medullary cavity. During the disappearing process of the medullary bone, osteoclasts showed significant increase in size and number (p less than 0.05). In irregular and flat bones, osseous trabeculae of the medullary bone became slender with age. The extramedullary hematopoiesis in the liver and spleen was very active till 30 days of age. This may suggest that the persistence of the medullary bone narrows the medullary cavity to cause poor medullary hematopoiesis and is compensated by extramedullary hematopoiesis. The relationship among the medullary bone, extramedullary hematopoiesis and piglet anemia was discussed.
大多数哺乳动物出生时，骨髓通常存在于长骨的骨髓腔内。在本研究中，对仔猪出生时及出生后骨髓腔内骨组织的存留情况进行了检查。出生后立即观察到，长骨的骨髓腔几乎完全被松质骨填满。存留的松质骨，即骨髓骨，在幼龄猪中较为明显，但随着年龄的增长而减少。到90日龄时，骨髓骨几乎消失，形成了扩大的骨髓腔。在骨髓骨消失的过程中，破骨细胞的大小和数量显著增加（p<0.05）。在不规则骨和平扁骨中，骨髓骨的骨小梁随着年龄增长而变细。肝脏和脾脏的髓外造血在30日龄前非常活跃。这可能表明，骨髓骨的存留使骨髓腔变窄，导致骨髓造血功能不佳，并由髓外造血进行代偿。文中还讨论了骨髓骨、髓外造血与仔猪贫血之间的关系。
