Photomicrographs illustrating the aromatase-immunoreactive perikarya (A) and the vasotocin-immunoreactive fibers (B, C) present within the medial preoptic nucleus (POM) that were quantified in the present study.

Panel A illustrates the dense group of aromatase-immunoreactive neurons that outline the entire POM. The dotted line marks the limits of the POM as they were defined for quantification. Panel B shows the accumulation of vasotocin-immunoreactive fibers in the POM at the level of the anterior commissure. The rectangle drawn with a solid line indicates the area where quantification was performed that is illustrated at higher magnification in panel C. The dotted rectangle indicates how the camera field was originally placed before being moved to its final location (see text). Note that quantification of fibers concerned the steroid-sensitive network located in the POM, not the denser network located more ventrally that originates from the magnocellular neurons. CA: commissural anterior, LFB: latera forebrain bundle. Magnification bar =  500 µm in A–B, 100 µm in C.