A symposium under the auspices of the Society of General Physiologists is planned for September 9-12, 1987, at the Marine Biological Laboratory in Woods Hole, Massachusetts. The general topic will be the cell physiology of blood cells--erythrocytes, leukocytes, and platelets. Five broad areas will be covered: (1) hematopoiesis, the regulation of differentiation and development of the three main cell types from stem cells, including the role of colony-stimulating factors and growth factors on stem cells maintained in tissue culture; (2) membrane skeleton and contraction, including the structure and functions of new contractile proteins in red cells and leukocytes and the relationships between surface antigens and skeletal proteins in platelets; (3) anion transport in red cells and neutrophils, including the sequence and topology of the band 3 protein in red cells and its modes of operation as a carrier, channel, and cotransporter of protons and anions; (4) ion channels and activation of blood cells, including patch-clamp measurements of K+ and Ca channels in lymphocytes, macrophages, and platelets; and (5) the phosphoinositide cycle and protein kinase C activation in the mediation of receptor signals from extracellular factors. Poster sessions will be held at which contributed papers of the most recent work related to these topics will be presented and discussed. Twenty-four speakers have been invited, including six from other countries. This symposium will offer a unique opportunity to bring together physiologists, cell biologists, biochemists, and hematologists with their different research interests in blood cells together at a single series of presentations to allow cross-fertilization and critical comparisons to take place. The lecture program will be held during five sessions, three in the morning and two in the afternoon. The contributed posters will be presented in one afternoon and one evening. A major keynote address is planned for one of the evenings and a symposium summary is planned at the conclusion of the last lecture program. The published proceedings are expected to make a timely and important contribution to this diverse and rapidly growing field.