Organization of the surface and adhesive properties of cleavage furrows in loach (Misgurnus fossilis) eggs

The experiments with chimerous embryos of teleost loach (Misgurnus fossilis) have shown that before furrows of the 1st cleavage appeared, the eggs were completely nonadhesive. At the stages of cleavages II-IV whole eggs were able to adhere and then make extended junctions in the blastodisc region. Adhesive domains of blastomeres were discovered by using carmine dye particles which attached primarily in the region of blastomere cleavage furrows. Scanning electron microscopy (SEM) showed that the cells in the depth of the cleavage furrows have domains with a smoother relief than their outer surface with numerous folds. Moreover, most adhesive flat lamellar formations (ruffles) with microvilli at their ends were discovered in the furrow region, particularly in its apical part (in the sites of intercellular contact formation and carmine absorption). Colchicine (5 X 10(-4) M) treatment affects the reorganization of the cleavage furrow surface, and the eggs, one by one, lose their ability to adhere, and then to attach dye particles. Mechanisms of formation of an adhesive contact between divided cells are discussed.