DEVELOPMENT OF SEROTONERGIC INNERVATION OF THE CHICK-EMBRYO TECTUM OPTICUM

This paper describes the development of the serotonergic innervation o f the chick tectum opticum as revealed by an immunohistochemical metho dology. The development of this innervation was previously described s imply as the formation of an irregular network of serotonergic fibers that gradually invades the organ and increases in density. Our results show that the developmental pattern of serotonergic innervation diffe rs significantly through the distinct tectal layers and that it progre sses through a characteristic temporospatial pattern related to the la mination process. These findings support the idea that the concept of laminar segregation can be applied to describe the development of the serotonergic innervation. On the other hand, it is clear that the exis tence of a typical ordered developmental pattern of innervation makes it possible to detect embryonic or post-hatching alterations. Thus, th e tectal serotonergic innervation could be used as a suitable model to investigate possible plastic changes in experimental conditions.