Hypothalamic innervation of the pituitary in the catfish, Clarias batrachus (L.): a retrograde horseradish peroxidase study.

Intrahypophysial administration of horseradish peroxidase (HRP) resulted in extensive labelling of the cells of nucleus preopticus and nucleus lateralis tuberis. Besides, isolated retrogradely labelled neurons were observed in the nucleus preopticus periventricularis in the preoptic area, nucleus of the horizontal commissure, nucleus hypothalamicus ventralis in the rostral tuberal area, and nucleus arcuatus hypothalamicus in the caudal tuberal area. A few labelled cells were also observed in the mamillary region.