Histochemical characterisation of the pretecto-geniculate projection in kitten and adult cat

Neurons in the pretectal nuclear complex projecting to the dorsal lateral geniculate nucleus (LGNd) in cat were studied at different postnatal ages by using a combination of retrograde tracing techniques with glutamic acid decarboxylase (GAD) in situ hybridisation and calbindin-D28K (CALB) and parvalbumin (PARV) immunocytochemistry. About 50% of the neurons retrogradely labelled from the LGNd expressed GAD mRNA and this percentage did not change during postnatal development. LGNd-projecting neurons were never observed to be CALB- or PARV-immunoreactive.