Organização e morfologia dos núcleos da rafe de embriões de galinha (Gallus gallus domesticus)

Abstract

The raphe nuclei (RN), located in the brainstem and characterized by their serotonergic neurons, play critical roles in both physiological and behavioral functions. While they are extensively studied in mammals, there is a notable gap in the understanding of the morphology of these nuclei in birds, particularly during development. This study aims to provide a morphological characterization of the RN in 19-day-old chicken embryos (Gallus gallus domesticus). Approved by CEUA/UFRN (419.055/2024), ten embryos were used and incubated under controlled conditions. The brains were extracted, processed, sectioned, and subjected to Nissl staining and serotonin immunohistochemistry, revealing both rostral and caudal clusters. The rostral cluster included the following nuclei: rostral and caudal linear, dorsal raphe (with its subdivisions), paramedian, B9, median, and pontine raphe. In the caudal cluster, the following nuclei were identified: raphe magnus, rostral and caudal ventrolateral, raphe pallidus, and raphe obscurus. The serotonin-immunoreactive neurons were predominantly rounded and were distributed throughout the brainstem. The results suggest that the organization of the RN in chicken embryos shares phylogenetic similarities with other vertebrates, while also exhibiting differences in the dorsal raphe, paramedian, median, and B9 nuclei. A comprehensive understanding of the neuroanatomy of these nuclei can contribute to future research in comparative and translational neuroscience.