title: Exoskeletons of Bougainvilliidae and other Hydroidolina (Cnidaria, Hydrozoa): structure and composition.
abstract: The exoskeleton is an important source of characters for the taxonomy of Hydroidolina. It originates as epidermal secretions and, among other functions, protects the coenosarc of the polypoid stage. However, comparative studies on the exoskeletal tissue origin, development, chemical, and structural characteristics, as well as its evolution and homology, are few and fragmented. This study compares the structure and composition of the exoskeleton and underlying coenosarc in members of "Anthoathecata" and some Leptothecata, but does so mainly in bougainvilliid polyps histological analyses. We also studied the development of the exoskeleton under experimental conditions. We identified three types of glandular epidermal cells related to the origin of the exoskeleton and the secretion of its polysaccharides component. The exoskeleton of the species studied is either bilayered (perisarc and exosarc, especially in bougainvilliids) or corneous (perisarc). The exoskeleton varies in chemical composition, structural rigidity, thickness, extension, and coverage in the different regions of the colony. In bilayered exoskeletons, the exosarc is produced first and appears to be a key step in the formation of the rigid exoskeleton. The exoskeleton contains anchoring structures such as desmocytes and "perisarc extensions."
authors.affiliation: Department of Zoology, Institute of Biosciences, University of São Paulo , São Paulo , Brazil.
authors.forename: María A
authors.initials: MA
authors.lastname: Mendoza-Becerril
authors.affiliation: Department of Zoology, Institute of Biosciences, University of São Paulo , São Paulo , Brazil.
authors.forename: José Eduardo A R
authors.initials: JE
authors.lastname: Marian
authors.affiliation: Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil; Center for Marine Biology, University of São Paulo, São Sebastião, São Paulo, Brazil.
authors.forename: Alvaro Esteves
authors.initials: AE
authors.lastname: Migotto
authors.affiliation: Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil; Center for Marine Biology, University of São Paulo, São Sebastião, São Paulo, Brazil.
authors.forename: Antonio Carlos
authors.initials: AC
authors.lastname: Marques
keywords: Exosarc; Histochemistry; Leptothecata; Perisarc; “Anthoathecata”