Why are bone and blood both classified as connective tissues?

Bone and blood both provide a structural framework for the body. For example, bones offer shape and support to the body so that it is able to stand upright. Another reason is because they establish connections between various body parts. For example, blood connects all systems of the body and transports nutrients, oxygen, and waste to different areas. A third reason is because these tissues originate from the mesodermal layer during development. Blood cells develop from a process called hematopoiesis. Hematopoietic stem cells arise from the mesoderm in the embryo. Mesenchymal cells, which are also derived from the mesoderm, are the precursors for bone cells. Lastly, blood and bones are considered to be connective tissues since they have matrixes. The organic matrix of bone is made up of collagen, which makes up 90% of bone matrix, and non-collagenous organic materials. In blood, the matrix refers to the fluid component known as plasma. The primary cell types found within this matrix are white blood cells and red blood cells.