Which type of white blood cells are NOT formed in bone marrow?

Lymphocytes are a type of white blood cell that are primarily generated in lymphoid tissues rather than in the bone marrow. While the precursor cells for lymphocytes originate in the bone marrow, lymphocytes themselves mature and proliferate in lymphoid organs such as the thymus and lymph nodes. This distinction is significant because it highlights the role of the immune system's network beyond the bone marrow, where other types of white blood cells like monocytes, eosinophils, and neutrophils are indeed formed and mature. Understanding the development pathways for different white blood cell types is essential for grasping how the immune system functions and responds to pathogens.