Complex sentence: Tumor infiltrating lymphocytes (TILs) are lymphocytes that penetrate a tumor and while have a common origin with myelogenous cells at the hematopoietic stem cell, diverge in development.
Split into simpler sentences: Tumor infiltrating lymphocytes (TILs) are lymphocytes that penetrate a tumor. TILs have a common origin with myelogenous cells at the hematopoietic stem cell, but diverge in development.