Reciprocal connections between the rabbit suprageniculate pretectal nucleus and the superior colliculus: Tracer study with horseradish peroxidase and fluorogold

Abstract

Connections of the rabbit suprageniculate pretectal nucleus (SP) with the superior colliculus were explored by means of retrograde transport of horseradish peroxidase or Fluorogold. Large injections centered in the superficial and intermediate tectal layers resulted in bilateral retrograde transport to the medium-size multipolar neurons of the suprageniculate pretectal nucleus. Horseradish peroxidase was also transported anterogradely into the ipsilateral and contralateral neuropiles of the suprageniculate pretectal nucleus. The labeled cells in SP were dispersed throughout the nucleus, including its dorsal, wedge-shaped, internal portion. Labeling was mainly ipsilateral, and less abundant on the contralateral side.

Specific regions within the embryonic midbrain and cerebellum require different levels of FGF signaling during development

“…3A,B). Histological analysis showed that only the anterior region of the dorsal midbrain, including the anterior-most mes-derived structure, the PPT (Lagares et al, 1994), appeared normal; tissue was missing at the posterior end of the SC; and the IC, dorsal isthmus and vermis were absent ( Fig. 3C-E).…”

The isthmic organizer signal FGF8 is required for cell survival in the prospective midbrain and cerebellum

“…Rostrally, all midbrain tissue except the posterior pretectal nucleus (PPT) was absent. Although its name implies that the PPT is of forebrain origin, comparative anatomical studies indicate that it is a midbrain structure derived from the rostral mesencephalon (Lagares et al, 1994). Caudally, no cerebellar tissue was observed, and the locus ceruleus was absent.…”

Identification of the Anterior Nucleus of the Ansa Lenticularis in Birds as the Homolog of the Mammalian Subthalamic Nucleus

“…Although a mammalian homolog of SpL has not been definitively identified (Reiner et al, 1984(Reiner et al, , 1998aCaballero-Bleda et al, 1992;Lagares et al, 1994), several lines of evidence indicate that SpL in birds is the target of an additional direct striatal output and is thereby analogous to mammalian GPi (Reiner et al, 1984(Reiner et al, , 1998aMedina et al, 1999). As is true of the GPi-like cell groups in mammals (i.e., GPi itself and SNr), SpL neurons are GABAergic, receive input from SP ϩ striatal neurons as well as from dorsal pallidal neurons that receive ENK ϩ striatal input (i.e., GPe-like pallidal neurons), and are notably enriched in GluR4 (Karten and Dubbeldam, 1973;Reiner et al, 1982aReiner et al, , 1984Veenman and Reiner, 1994;Reiner, 1996, 1997; Pa- Karten and Hodos (1967).…”