GROWTH AND MORPHOGENESIS OF SOME MARINE HYDROZOA ACCORDING TO HISTOLOGICAL DATA AND TIME-LAPSE STUDIES

Abstract

Factors of embryonic polarization in Clava multicornis and Obelia loveni and cellular mechanisms of growth and morphogenesis of vegetal generation mainly in Obelia loveni and Dynamena pumila were studied. Morphological axis of embryo was found to be not determined irreversibly up to morula stage. Unequal distribution of mitotic divisions was demonstrated to be a main cause of embryo elongation. No definite relations were registered between shape and/or growth rate of vegetal rudiments and the characteristics of proliferative processes. Using time-lapse methods, a pulsatory character of growth and shapening was revealed. Growth pulsations are underlined by periodical contractions-extensions of densely packed cells of ecto- and entoderm. Some modes of behaviour of a system, composed by contractile, densely packed cells, are formulated. A number of normal and experimentally modified morphogenetic processes in Hydrozoa may be regarded as direct consequences of the properties of such systems.