Lymph nodes - not lymphoma

Topic Completed: 1 November 2013

Minor changes: 1 April 2020

Revised: 1 February 2019, last major update November 2013

Copyright: 2003-2020,, Inc.

PubMed Search: Embryology [title] lymph nodes

Nat Pernick, M.D.
Page views in 2019: 119
Page views in 2020 to date: 47
Cite this page: Pernick N. Normal: embryology. website. Accessed May 27th, 2020.
Definition / general
  • Develop from lateral plate mesoderm (on either side of intermediate mesoderm)
  • First, lymphatic sacs arise from endothelial outgrowths of large central veins at week 5
  • Second, lymphatic plexus develops from lymphatic sacs
  • Third, plexuses are invaded by mesenchymal cells that proliferate and aggregate to form lymph nodes
  • Small collections of lymphoblasts are present by first trimester
  • By second trimester, cortex is distinguishable from medulla and primary follicles are present
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