Abstract
Sea urchin embryos, 8-cell stage to pluteus stage, fixed in osmium tetroxide and embedded in Epon 812 were observed by electron microscopy. At no point in the development were syncytial junctions between the embryonic cells found. During the cleavage stages the membrane contact was closer than in later stages. In early blastula stages intercellular clefts appeared which in the gastrula stage demarcate every cell. At the same time a ringshaped desmosome structure develops at the outer cell surface. In the pluteus stage a closer cell contact is re-established. With proceeding embryogenesis endoplasmic membranes will attach to the cell membrane. These membrane structures may even be of nuclear origin. Gradually, long protrusions, vesicles and lamellae begin to be formed from the nuclear membrane. The commencement of this nuclear activity coincides in time with the formation of nucleoli. At cell division the new cell membrane seemed to arise partly independently of the cleavage furrow from a system of cytoplasmic vesicles.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Zeitschrift f�r Zellforschung und Mikroskopische Anatomie
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
