Generation of proplatelets from normal mouse fetal liver cultures. (A) Appearance of normal fetal liver megakaryocytes generating normal proplatelet processes when cultured with 5% A/J +/+ sera. (B) Appearance of normal fetal liver megakaryocytes cultured with 5% A/J-trac/trac sera failing to generate proplatelet processes. Representative samples were stained with rabbit polyclonal antibody SUP GLU, diluted 1:1000, which recognizes detyrosinated tubulin. Bar represents 5 μm. (C) Seventy-one percent of normal fetal liver megakaryocytes generated proplatelet processes when cultured with 5% A/J +/+ sera versus 26% when cultured with 5% A/J-trac/trac sera.