The CMY colours (commonly mistaken for Blue, Red and Yellow) are the answer when printing as mixing any two will form one of the darker RGB colours. The mix of all three CMY colours creates Black, although in practice this is very muddy.
White blood cells, like all blood cells are created in the bone marrow from certain stem cells. However, some lymphocytes are created but undeveloped or immature.
1 The lymphatic system is an important part of the immune system. 2  The lymph nodes filter lymph fluid as it flows through them, trapping bacteria, viruses, and other foreign substances, which are then destroyed by special white blood cells called lymphocytes. The tonsils and thymus, which make antibodies. 2  The lymph nodes and vessels (the lymphatic system). 3  This network of lymph nodes and vessels throughout the body carries lymph fluid, nutrients, and waste material between the body tissues and the bloodstream. 4  The lymphatic system is an important part of the immune system.