Studies on the fine structure of teleost blood cells

Summary Electron microscopic study of nucleated erythrocytes of the goldfish, Carassius auratus, reveals the microtubular elements comprising the marginal band which encircles the cell. Six to ten units are visible at each pole of the cell, immediately within the plasmalemma. Each tubular unit is composed of an electron dense membrane enclosing a less dense core. Cross-sectional units average 264 Å outer diameter, whereas tubules measured in longitudinal sections average 237 Å.The functions of the microtubules of the marginal bands are analyzed in view of Meves' original interpretation of maintenance of the discoidal form of the nucleated erythrocyte, and the more recent investigations in cell physiology of Trotter and Tilney. It is proposed that the microtubules possess a dual function: the support of the cell which is attributed to the hydroelastic properties of the turgid microtubules resulting from intratubular hydrostatic pressures; and the intracellular transport of materials via the intratubular fluid. The microtubules may, therefore, be considered as a skeletal system and part of an intracellular circulatory system.This project was supported by grants 2 G-895 and 2 G-505 from the United States Public Health Service.