Studies on the neuroendoerene activity in the central nervous system tem of newly hatched crayfishes (Astacus leptodactylus Eschz.) related to the light adaptation

Konok, István (1963) Studies on the neuroendoerene activity in the central nervous system tem of newly hatched crayfishes (Astacus leptodactylus Eschz.) related to the light adaptation. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 30. pp. 37-43. ISSN 0365-3005

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Abstract

Evaluating macro- and micromórphologically the experiments concerning the light adaptation in newly hatched crayfishes the followings were established as regards their neuroendocrine activity. 1. There are already all types of chromatophores resp. all kinds of pigments with the exception of xanthophores present in great quantity in the integument. The number of xanthophores is still small both in absolute and in relative sense. 2. The light-adaptive arrangement of pigments takes place in a way similar to that observed in adult animals. The accommodating migration of the proximal retinal pigments of ocelli equals also to that observed in adults. 3. In comparison with adult animals there are morphological differences regarding the direction of the position of single medullae in the eye-stalk. The number of secretory neurons present in the medulla terminális X organ is still low, there are no A type cells present, and no activity is observable. 4. Changes in the relative quantity of granular cells in relation to the single phases of adaptation are also observable. 5. The central nervous system is not yet completely developed morphologically. Indicative of that is the incomplete fusion of the six pair ganglia forming the subesophageal ganglion, further the fact that the other ganglion pairs of the nerve cord are still in direct contact with each other—due to their size, resp. to the shortness of their connectives. 6. A continuous common secretory cell „envelope” covers ventrally not only the fused ganglia but also those connected with each other. 7. One paraesophageal ganglion is present on each connective running along on both sides of the esophagus. The basic difference between these ganglia and similar organs described by other authors in other groups of crustaceans is that they do not contain only motoric neurons but a considerable part of the small sized ganglia is constituted of secretory neurons. 8. The secretory cells present in large number in the brain and in the ganglia of the nerve cord are in the phase of a strong activity. The existence of such a strong neuroendocrine activity is suggested also by observations made on both the hormone transport and the morphological picture of sinus gland.

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