Veterinary Immunology and Serology

BONE MARROW

• The specialized ileo-cecal Peyer’s patches (PP) have been described in ruminants and pigs. In other species, bone marrow serves as the primary lymphoid organ for B cell development.
• The bone marrow is the site of generation of all circulating blood cells in the adults including immature lymphocytes and also the site of B cell maturation.
• In the embryonic life, hematopoiesis (generation of blood cells) starts in blood island of yolk sac and the para-aortic mesenchyme and latter in the liver and spleen. Gradually this is taken over by the bone marrow after birth.
• At puberty, hematopoiesis mostly occurs in the flat bones (sternum, vertebrae, iliac bone, ribs etc.).
• The red marrow consists of sponge like reticular framework lined in the endothelium and found between long tuberculae.
• The spaces in this framework are filled with fat cells, stem cells and hematopoietic cells.
• These precursors mature and exit through the network of vascular sinuses to the vascular circulation.
• All blood cells except T lymphocytes are produced in the bone marrow.