A comparative study of the mesoglea of some cnidiarians was made by histochemistry techniques and by electron microscopy. Histochemistry enabled the presence of collagen fibers in the mesoglea of Velella (Siphomedusa) and of Millepora (colonia Hydrozoa), to be ascertained. In other forms, such as Cladonema radiatum (Anthomedusa), Gonionemus vertens (Limnomedusa), Rhizostoma pulmo (Scyphomedusa) and Cerianthus membranaceus (Anthozoa), the same methods show the existence of two different types of fibers in the mesoglea. Thin sections of the mesoglea of Cladonema radiatum and Gonionemus vertens, examined in the electron microscope, show that collagen is present in a felt-like formation of varying density, made up of fibers of very small diameter. The other fibers are thicker, ramified and undulating; they have the ultrastructural appearance of elastic fibers and have been identified as oxytalan fibers. |
