Fig. 6

Localization of crh forms in the hypothalamus of fishes. (A) Representative transverse section of the spotted gar (Lepisosteus oculatus) brain stained with cresyl violet, with the approximate region of interest indicated (black box). (B) crh1-expressing cells were abundant in the ventral hypothalamus (Hv) of the gar, in the region above the pituitary (pit). (C) crh2 expression was absent from the hypothalamus of the spotted gar. (D) Representative transverse section from the zebrafish (Danio rerio) brain atlas (Wullimann et al., 1996), with the region of interest indicated (black box). (E) Zebrafish crhb-expressing cells were found in the nucleus lateralis tuberis (NLT) (labeled ventral hypothalamus, Hv, in atlas), but were also widely distributed throughout the brain. (F) Zebrafish crha expression was found exclusively in the NLT, and nowhere else in the brain. (G) Representative transverse section of the cichlid (Astatotilapia burtoni) brain stained with cresyl violet, with the approximate region of interest indicated (black box). (H) crhb-expressing cells were abundant in the NLT region above the pituitary gland of the cichlid. (I) crha expression was not detectable in the cichlid brain. Insets on (A,D,G) show lateral view of the brain with approximate location of transverse sections indicated (line). For each species, panels are adjacent sections labeled with different anti-sense crh probes. Hv, ventral zone of the periventricular hypothalamus; LH, lateral hypothalamic nucleus; NLTm, medial part of lateral tuberal nucleus; NLTv, ventral part of lateral tuberal nucleus; pit, pituitary; T, tectum. Scale bars = 100 μm (B,C); 25 μm (E,F,H,I).