During fetal development, hematopoiesis occurs in distinct tissues at different stages. The yolk sac is initially significant, producing primitive blood cells. The fetal liver then becomes a major site of blood cell production, followed by the spleen. Ultimately, the bone marrow becomes the primary organ for blood cell production, reflecting changing developmental needs.

Hematopoietic stem cells, found in the bone marrow, continuously produce diverse blood cell types, but are limited to the hematopoietic lineage. They maintain blood system balance, aid in immune response, and have clinical applications, making them crucial in treating blood-related disorders. Their multipotent nature is showcased in their ability to repopulate the blood cell repertoire.

Cellular plasticity allows cells to differentiate into various types, with varying degrees of potential. Totipotent cells, like the zygote, can form any cell in an organism, including extraembryonic cells. Pluripotent cells, such as embryonic stem cells, can differentiate into cells of all three germ layers. Multipotent cells, like adult stem cells, have a more limited differentiation potential.