Size uniformity of ribonucleoprotein matrix particles in loops of Pleurodeles waltlii lampbrush chromosomes visualized by electron microscopy. 
The different kinds of loops of lampbrush chromosomes were identified in phase contrast, then analysed by electron microscopy on thin sections.  Examination at high magnification showed that the basic structure of the ribonucleoprotein (RNP) matrix of all kinds of loops is a 30 nm RNP particle.  Furthermore, this study suggests that the morphological differences between the loops are due to the extent of aggregation of these particles.