From Stem Cell to Structure: Neurogenesis in the CNS of Decapod Crustaceans

Abstract

In recent years, studies on the structure of the developing crustacean CNS were hampered by the fact that only a relatively small number of methods apart from classical histology (e.g., Scholtz 1992; Harzsch and Dawirs 1993, 1995/96; Helluy et al. 1995, 1996; Roulant et al. 1994, 1995; Gerberding 1997) were available. Immunohistochemistry and in situ hybridization were used to reveal the ontogeny of neurotransmitter and neuroendocrine systems (see below). The general morphology of the embryonic CNS was investigated by neuron-specific antibodies (Dumont and Wine 1987; Meier and Reichert 1990; Garzino and Reichert 1994) and rhodamine phalloidin staining (Whitington et al. 1993; Scholtz 1995a,b) while axogenesis was analyzed by intracellular tracing techniques (Whitington et al. 1993; Gerberding and Scholtz 1999). Most of these developmental papers dealt with malacostracan crustaceans (Fig. 1), whereas little attention was paid to the ontogeny of the CNS in entomostracans. The recent finding that antibodies directed against acetylated a-tubulin and Drosophila synaptic proteins (synapsins: Klagges et al. 1996) strongly cross react within the crustacean CNS (Harzsch et al. 1997) has contributed a new item to the toolbox of the carcinologists who study development. Immunohistochemistry against synapsins has now proven to be a valuable method to examine the structure of both the immature (Harzsch et al. 1998, 1999a,b, 2000a) and adult crustacean CNS (various authors, this Vol.).