[Development of the neurosecretory system of the eyestalk of larval Astacus leptodactylus salinus (Crustacea Decapoda Reptania): photon microscopy].

Using the alcian blue-alcian yellow staining method, the neurosecretory system in the eyestalk of the Crayfish Astacus leptodactylus is studied during the period following the first, second, third and fourth moult after hatching. On the basis of their staining affinities, six different cell types are distinguishable, always spread over the four optic ganglia and varying in number depending upon the moment of sampling. A clearly recognizable sinus gland is present in the period following the third and fourth moult after hatching. During the successive stages, there occurs a shift in staining pattern of the sinus gland, which is also expressed by the variation in number of the various stained cell types.