Where do B cells and T cells complete their maturation?

1. Every cell of the immune response arises in the bone marrow by differentiation from hematopoietic stem cells. 2. The B cell undergoes nearly all of its development in the red bone marrow. 3. The immature T cell, called a thymocyte, leaves the bone marrow and matures largely in the thymus gland. 4. Bone marrow and thymus are therefore the two primary lymphoid organs, where lymphocytes mature, proliferate and are selected. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 21 "The Lymphatic and Immune System", section 21.1 Anatomy of the Lymphatic and Immune Systems_