Fig. 1.

PSA-NCAM expression in SON and PVN of virgin and lactating rats. a, Photomicrograph of a coronal section from adult rat brain, at the level of SON (arrow) and PVN (arrowhead) hypothalamic nuclei; Kluver and Barrera staining. b–e, Photomicrographs of PSA-NCAM immunostaining in SON (b, c) and PVN (d, e) nuclei of virgin (b, d) and 10 d lactating (c, e) rats. During lactation, polysialic acid immunoreactivity is dramatically decreased in both nuclei, whereas the rest of the hypothalamus remains highly stained. Magnifications:a, 17×; b, 67×; c, 80×;d–e, 120×.