Fluorescence microscopy of the catecholamine-containing neurons of the hypothalamohypophyseal system

Summary The hypothalamohypophyseal system of the mouse, rat, guinea-pig, cat, dog and monkey (Macaca mulatta) was studied with the fluorescence method for catecholamine-containing neurons developed by Falck et al. (1962). The fluorescent fibers are prominent in the external layer and around the primary portal plexus of the infundibulum and in the peripheral region of the neural lobe of these animals, particulary on the external surface and surrounding the primary capillary loops. These fluorescent fibers are connected with fluorescent cells in the arcuate nuclei, and this connection coincides with the tuberohypophyseal system. The neurons of this system have a particular affinity for dopamine, possibly due to their own content of dopamine. In the supraoptic and paraventricular nuclei, no fluorescent cells were found. In the pars intermedia, we also found catecholamine-containing fibers.The presence of catecholamine-containing fibers in the adeno- and neurohypophysis are considered in relation to other data derived from fluorescence and electron microscopy.