Immunocytochemical reactions occur in the Crinoïd: Antedon bifida, in the Asterids: Asterina gibbosa and Asterias rubens.Various antigens (HRP or Horse-radish peroxydase, Alkalin phosphatase) were injected in the animal's coelomic cavity. Animals were "immunized". Observations were done in TEM (Transmission electronic microscopy) by the use of specific labelling and in light microscopy.IN TEM immune labelling were seen in the perinuclear space (EP) rough ergastoplasm (RE) Golgi apparatus (G) and Lysosomes (L): the"antibody" biosynthesis in Invertebrates was clearly shown though the animal kingdom. It is the first time we can observe such phenomena. We show in this book immunocytochemical reactions which were done in 2 Echinodermata (Invertebrates).