OBO_REL:part_of (UNDECLARED) compound organ kidney head kidney TAO:0000669 The zebrafish head kidney consists of fused bilateral lobes located in the anterior part of the kidney. It is analogous to the mammalian bone marrow and the primary site of definitive hematopoiesis. Davidson and Zon 2004. anterior kidney kidney marrow teleost_anatomy endocrine system hematopoietic system