• lymphocytes
  • In the case of mammals such as humans, lymphopoiesis begins with limited passive provision by the mother of lymphocytes and substantial immunoglobulin G that cross the placenta and enter the fetus to provide some protection against pathogens, and also leukocytes that come from breast milk and enter circulation via the digestive tract. (wikipedia.org)
  • blood
  • The partial loss of or loss of function of any white blood cell type is a serious health matter and lymphopoiesis is absolutely necessary for life. (wikipedia.org)