The torus longitudinalis in the gilthead seabream: an undescribed fiber tract link with the valvula cerebelli

Abstract

In this paper, we present a brief anatomical description of the torus longitudinalis and the valvula cerebelli in a percomorph fish, the gilthead seabream (Sparus aurata) based on the analysis of serial brain sections stained by paraldehyde fuchsin, Groat's hematoxylin-picroindigocarmin and cresyl violet. The existence of a small undescribed fiber tract directly bridging the ventral torus longitudinalis and the granular layer of the rostral valvula cerebelli is also reported. This small fiber tract was observed in its integrity on a few transverse sections providing that the angle of sectioning was appropiate. The existence of the anatomical link between the TL and the VC described in this paper might sustain the role of the TL as part of an ascending cerebello-tectal circuit, at least in gilthead seabream. However, these fibers might also represent fibers of passage originating from other brain structures.