AbstractImmunohistochemical staining of tissue sections prepared from gonads and gonad‐associated tissues obtained from adult chickens was performed in order to assess the possibility that these tissues may be sites of enrichment with IgM‐containing cells in various B lineages. Evidence is presented which suggests that IgM‐containing B lineage cells are present in 1) the ovarian stroma and subcapsular areas of the ovary and 2) the interstitium and subcapsular areas of the epididymis of the testes. These represent new sites reported for B lineage cells in adult chickens. Some questions relevant to the physiologic, ontogenetic, and phylogenetic implications of these observations relative to vertebrate hematolymphopoietic processes are included. © 1995 Wiley‐L