Alexander Drozdov

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The ultrastructure of male and female gametes of asconoid sponge Leucosolenia complicata(Calcispongiae, Calcaronea), a hermaphrodite species that reproduces in autumn, is described. The mature sponge's oocytes were up to 70 μm in diameter, had no coatings, and contained a nucleus about 31 μm in diameter with large nucleoli (up to 6.6 μm). There were(More)
The ultrastructure of primary spines (microscopic relief of the surface of radial wedges on the spines and cross-sections of the spines) was studied by scanning electron microscopy in seven sea urchin species of the family Strongylocentrotidae. The spines were taken from the ambitus area of equally sizes individuals with a test diameter of 50 ± 5 mm.(More)
Ovogenesis of the Barents sea sponge Leucosolenia complicata Mont. having asconoid canal system was studied at light (using histochemical methods) and ultrastructural levels. It has been established that the reproduction period "arranges" for autumn-winter season. The ovogenesis lasts for approximately two months. Grand accroissement is the longest stage of(More)
The ultrastructure of sperm in seven species of bivalves, the representatives of six families, Arcidae (Anadara broughtonii, Arca boucardi), Anomiidae (Pododesmus macrochisma), Tellinidae (Macoma tokyoensis), Ostreidae (Crassostrea gigas), Myidae (Mya japonica) and Trapezidae (Trapezium liratum) is described. All the studied sperm were typical tail sperm,(More)
Glass sponges of the class Hexactinellida are a group of the most ancient multicellular animals, whose fossil remnants from the early Proterozoic have been registered. In order to demineralize the skeletal structures of the glass sponge Hyalonema sieboldi, we have used for the first time a strategy of slow leaching of the silicon-bearing component, based on(More)
Originating in nature, the combination of spongin protein with silicon dioxide extracted from seawater by silicatein protein presents a natural nanocomposite material of unique optical and mechanical properties. Mechanically, it combines the elasticity of protein with the flexibility and durability of silica. The light propagation inside spicules of glass(More)
The fine structure of the gametes in six sea urchin species of the Sea of Japan was studied. The sperm in Strongylocentrotus nudus, S. intermedius, Echinocardium cordatum, Scaphechinus mirabilis, Sc. griseus and Echinarachnius parma are species-specific. The conical head and symmetrically disposed ring-shape mitochondrion are common to regular sea urchin(More)
The ultrastructure of the sperm of the common bivalve species Mercenaria stimpsoni and Mactra chinensis from Peter the Great Bay is described. The sperm structure is typical for animals with external insemination. The sperm consists of a head, middle part, and flagellum. The sperm head of M. stimpsoni has a curved crescent form and includes the nucleus and(More)
The ultrastructure of spermatozoa of Cucumaria japonica and a congeneric morphologically similar deep-sea species was studied. The spermatozoa of both C. japonica and C. conicospermium are similar to those of other holothurians: the acrosome is composed of an acrosomal granule and periacrosomal material; the centrioles lie at an acute angle to one another;(More)
The study is concerned with the polymerization of myorod, a protein from thick filaments of molluscan smooth muscles, which is an alternative product of the gene of myosin heavy chains. The dependences of the properties and polymer structure of myorod on the conditions of its formation were investigated. It was shown that myorod loses the ability to form(More)