THE LIPOPROTEIN CRYSTALS IN YOLK PLATELETS OF A SHARK, SQUALUS-OCANTHIAS (SELACHII)

Lipovitellin-phosvitin crystals in yolk platelets from the egg of a sh ark, Squalus ocanthias (Selachii), were studied by the selected area e lectron diffraction method. Ultra-thin sections of yolk platelets poss ess an orthorhombic lattice with lattice parameters: a = 8.0nm, b = 15 .9nm, and c = 18.1nm. Comparative and quality analysis of the reflecti on intensities of electron diffraction patterns between shark and othe r vertebrate yolk platelets suggest evolutionary variability of the li povitellin structure. The lattice and its parameters, however, are hig hly conserved. The results of the present study fill the last gap in t he comparative yolk platelet research which has been carried out over many years for exponents of all vertebrate taxonomic groups, from cycl ostomes to reptiles.