Light microscopic analysis of cellular networks in the pineal gland of the golden hamster as revealed by methylene blue labeling.

Pineal glands of golden hamsters were stained transcardially with methylene blue and studied in paraffin sections by light microscopy. In the superficial portion of the pineal complexes, a selective labeling of a subpopulation of polymorphic cells with processes of different length was achieved. It could not be clarified, whether these cells form a syncytium or are only in contact with each other. Although functional interpretations of the morphological results have to be drawn with great care, the investigation might be of special interest for a better understanding of the well-known inhibiting effects of the dye to soluble guanylyl cyclase and nitric oxide synthase within this neuroendocrine gland.