Atlas of the telencephalon based on cytoarchitecture, neurochemical markers, and gene expressions in Rhinogobius flumineus [Mizuno, 1960]

Abstract

Gobiida is a basal subseries of percomorphs in teleost fishes, holding a useful position for comparisons with other orders of Percomorpha as well as other cohort of teleosts. Here, we describe a telencephalic atlas of a Gobiida species Rhinogobius flumineus (Mizuno, Memoirs of the College of Science, University of Kyoto, Series B: Biology, 1960; 27, 3), based on cytoarchitectural observations, combined with analyses of the distribution patterns of neurochemical markers and transcription factors. The telencephalon of R. flumineus shows a number of features distinct from those of other teleosts. Among others, the followings were of special note. (a) The lateral part of dorsal telencephalon (Dl), which is known as a visual center in other teleosts, is composed of as many as seven regions, some of which are conspicuous, circumscribed by cell plates. These subdivisions of the Dl can be differentiated clearly by differential soma size and color with Nissl‐staining, and distribution patterns of neural markers. (b) Cell populations continuous with the ventral region of dorsal part of ventral telencephalon (vVd) exhibit extensive dimension. Especially, portion 1 of the central part of ventral telencephalon appears to represent a cell population laterally translocated from the vVd, forming a large cluster of small cells that penetrate deep into the central part of dorsal telencephalon. (c) The magnocellular subdivision of dorsal part of dorsal telencephalon (Ddmg) contains not only large cells but also vglut2a‐positive clusters of small cells that cover a wide range of the caudal Ddmg. Such clusters of small cells have not been observed in the Ddmg of other teleosts.

Afferent and efferent connections of the nucleus prethalamicus in the yellowfin goby Acanthogobius flavimanus

“…For now, therefore, we regard the periventricular region in question as a part of Dc in the yellowfin goby. It should be noted that the periventricular region of Dc in the present study does not correspond entirely with that of Kawaguchi et al (2019) in a closely related goby R. flumineus . A different zone can be recognized rostromedially adjacent to the periventricular Dc as defined here in the present study.…”

“…The dorsal telencephalon of the yellowfin goby is highly complex. We therefore briefly describe subdivisions of the Dl, Dd, and Dc which are especially complex and turned out to be major targets of ascending PTh fibers, basically following the telencephalic atlas of a closely related species R. flumineus (Kawaguchi et al, 2019).…”

“…As judged simply from its position and cell size, this zone may perhaps be a portion of the Dm. Due to the unclear identity of this zone, however, we tentatively call it "X" in the present study (Figures 1a,b and 3).A smaller, medial region of the Dc becomes separated from the Dc proper interrupted by the invasion of a region of the ventral telencephalic area (Region 1 of central part of the ventral telencephalic area: Vc1;Kawaguchi et al, 2019). This small region of Dc, which also projects to the optic tectum like the Dc proper and periventricular region of the Dc(Figure 4a,b), is called the medial region of Dc(Dcm) in the present study(Figure 1c,d).…”

“…The Dc is composed of large cells in the central zone of the dorsal telencephalon from rostral to caudal level (Figure 1a-e). Although Furlan et al (2017) suggested that the Dc is strictly a deep structure in zebrafish, cytoarchitectonic analyses and distribution of ancillary markers suggested the presence of the periventricular region of Dc in a goby R. flumineus (Kawaguchi et al, 2019). A similar, periventricular region is also recognized in the yellowfin goby on the basis of F I G U R E 1 Cresyl violet-stained transverse sections through the rostral to caudal telencephalon of the yellowfin goby.…”

“…It should be noted that the periventricular region of Dc in the present study does not correspond entirely with that of Kawaguchi et al (2019) in a closely related goby R. flumineus. A different zone can be recognized rostromedially adjacent to the periventricular Dc as defined here in the present study.Although this zone was included in the periventricular region of Dc in R. flumineus(Kawaguchi et al, 2019), component cells are smaller and more densely distributed than those in the periventricular Dc, and are not retrogradely labeled from the tectum. Therefore, this rostral zone may not be regarded as a part of Dc.…”