Sea star Axial organ (A.O) cells were observed in T.EM. The axial organ has been described by us as a primitive
lymphoïd organ in the years 1970. Sea star lymphocytes, platelets, have already been observed in previous works .
They are smaller in diameter (4 to 5μ) than Vertebrate ones It seems to us that Thrombocytes exist also in this Invertebrate
(TEM observations) Genomics asserts this last data.