Primary lymphoid organs:
Bone marrow – source of all blood cells (hematopoiesis); site of B cell maturation.
Thymus – site of T cell maturation.
Secondary lymphoid organs:
Lymph nodes, spleen, tonsils, mucosa-associated lymphoid tissue (MALT) – sites where immune cells encounter antigens and initiate responses.
Mucusa Associated Lymphoid Tissue (MALT)
Reference
https://offers.the-scientist.com/hubfs/downloads/TS/TS_10XGenomics/TS_10x%20Genomics_Immune%20System_Infographic/10x_IM_Multiomic-Infographic_Digital_07302020_final.pdf?hsCtaTracking=ed50f208-52e5-4217-b2da-8d229cc7b6f0%7Cd5d3f369-c754-4c34-a137-859b941a7d22