title: Ultrastructure of auxiliary and gonimoblast cells during carposporophyte development in the red alga Cryptopleura ruprechtiana (Delesseriaceae, Ceramiales, Rhodophyta).
abstract: The ultrastructure sequence for the complete post-fertilization development is described in Cryptopleura ruprechtiana (C. Agardh) Kylin, a member of the Delesseriaceae. Following fertilization the diploid nucleus is transferred to the auxiliary cell. This contains typical red algal proplastids, cytoplasmic concentric membranes, numerous small vacuoles and lipid bodies. Crystalline inclusions and virus-like particles are also present. In addition darkly staining spherical masses possibly represent dehydrated haploid chromatin. The multinucleate auxiliary cell produces initially one large gonimoblast initial and subsequently many smaller gonimoblast initials. The first formed generative gonimoblast cell is similar in cellular structure to the auxiliary cell. Gonimoblast initials are uninucleate but through caryokinesis they become multinucleate. They undergo repeated cleavage to form more gonimoblast cells. Subsequent, centripetal cytokinesis results in the formation of clusters of gonimoblast cells. A new type structural cap or association is observed in the septal plugs that interconnect gonimoblast initials. Terminal or generative gonimoblast cells cleave to form additional gonimoblast cells. Only terminal gonimoblast cells are differentiated to carpospores.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D050356:Lipid Metabolism; D008854:Microscopy, Electron; D009685:Nuclear Envelope / Q000648:ultrastructure; D011523:Protoplasts / Q000648:ultrastructure; D000461:Rhodophyta / Q000502:physiology* / Q000648:ultrastructure*; D013170:Spores / Q000648:ultrastructure*; D020524:Thylakoids / Q000648:ultrastructure