Abstract
Selective staining of the neurosecretory hypothalamic-neurohypophyseal system is dependent on avoiding alcohol fixatives and on oxidation of the sections before staining. Mordanting before staining is recommended but not necessary. A large number of nuclear stains will give positive results. The neurosecretion seems to occur in places where fat-staining substances are found, and fails to stain after treatment with trypsin. This suggests that this neurosecretion is a lipoprotein.