The lipoprotein crystals in yolk platelets of a shark, Squalus ocanthias (Selachii).

Lipovitellin-phosvitin crystals in yolk platelets from the egg of a shark, Squalus ocanthias (Selachii), were studied by the selected area electron diffraction method. Ultra-thin sections of yolk platelets possess an orthorhombic lattice with lattice parameters: a = 8.0 nm, b = 15.9 nm, and c = 18.1 nm. Comparative and quality analysis of the reflection intensities of electron diffraction patterns between shark and other vertebrate yolk platelets suggest evolutionary variability of the lipovitellin structure. The lattice and its parameters, however, are highly conserved. The results of the present study fill the last gap in the comparative yolk platelet research which has been carried out over many years for exponents of all vertebrate taxonomic groups, from cyclostomes to reptiles.