Tectal neurons projecting to the isthmo-optic nucleus in the Japanese quail

Horseradish peroxidase (HRP) injected into the isthmo-optic nucleus (ION) of the Japanese quail retrogradely labeled neurons in the ipsilateral optic tectum. Some of these neurons exhibited a characteristic 'willow-like' appearance. Somata of these neurons were round or pyriform, usually located in lamina h of the stratum griseum et fibrosum superficiale (SGFS), and emitted several thin dendritic branches that ramified in the deeper laminae of SGFS but not in the retinal recipient laminae of SGFS. Their axons had horizontal processes ramifying in the deepest lamina of SGFS or the stratum griseum centrale.