Morphological and Biochemical Characteristics of Glycogen Particles Isolated from Rabbit Polymorphonuclear Leukocytes

The fine structure of ascitic cells, consisting of 87-92% heterophil, 5-10% eosinophil leukocytes, and 3% macrophages, is well preserved by glutaraldehyde-osmium tetroxide fixation only when the osmolality of the fixative is appropriately balanced. The beta-glycogen particles, 35-45 mmicro in diameter, are found either as large accumulations in the perinuclear region or in a dispersed form in peripheral cytoplasm. In the heterophils, they are embedded in a coarse-grained ground substance. Extraction and purification of the glycogen were performed by differential precipitation-centrifugation. Yield (35% recovery), purity (4% protein contamination), and preservation of a high sedimentation coefficient (240S) represent the main advantages of the proposed procedure. The analysis of the profile of the sedimentation curve, together with an analysis of the particle size measurements and of particle fine structure, leads to the conclusion that the beta-particles form a homogeneous population with a gaussian distribution curve. Each particle consists of smaller units which increase in number with increasing size, the largest ones taking on the appearance of small rosettes. The glycogen particles of the microsomal fraction, still loaded with phosphorylase, were submitted to a synthetic activity by incubation in the presence of glucose-l-phosphate. The analysis of the particle growth shows that particles of all sizes respond equally well.