ABSTRACT
Spatial and temporal expression of collagen in an echinothurioid echinoid Asthenosoma ijimai was examined immunohistologically using polyclonal antibody against collagen purified from the test of A. ijimai. Fertilized eggs of A. ijimai were cultured at room temperature (RT, ca.25°C) in a beaker without shaking. Specimens were fixed in seawater containing 4% formalin at various developmental stages from wrinkled blastula just before hatching to juvenile, dehydrated with an ethanol series, embedded in polyester wax, sectioned (5µ m), and stained with a polyclonal antibody against collagen purified from the test of A. ijimai, using rhodamin conjugated goat anti-rabbit IgG antiserum as a secondary antibody. Collagen molecules were expressed first on the hyaline layer at the stage just after the wrinkled blastula (26 hr post-insemination, biscuit-shaped embryo), and later on the basal lamina just at the start of metamorphosis (88.5 hr post-insemination) . As metamorphosis proceeded, collagen became evident on the inner surface layer facing the coelom, and in an intermediate layer of the tube foot (101 hr post-insemination). In the 20-day juveniles, collagen molecules appeared to be associated with the skeleton. These results indicate that the collagen isolated from the adult test of an echinothurioid echinoid, A. ijimai, corresponds to type I and type IV collagen of mammals, and that some molecules of the adult collagen are expressed as early as early-gastrula stage.
