| |
Fig. 4. T 3 strongly potentiates the induction of Vit mRNA by E 2 in livers of Xenopus tadpoles at late stages of metamorphic climax. Vit mRNA
accumulation was visualized by in situ hybridization in saggital sections of livers of stage 63/64 tadpoles treated or not with 10-7M E 2 alone or
pre-treated with T 3 for different periods of time. Where animals were pre-treated with T3, it was maintained in the water throughout the period
of exposure to E 2. Hybridization was performed with 35S-labelled sense and antisense cRNA probes derived from pXlvc 10 Xenopus vitellogenin
B1 cDNA (Wahli et al., 1979). Only the dark-field imaging with the antisense probe (a,c-f) is shown since the sense probe gave a negative signal
after 1 week of exposure for autoradiography. (a) Dark-field image of control (untreated) tadpole liver. (b) Bright-field image of liver of control
tadpole. (c) Liver of tadpole after 1 day treatment with E 2 alone. (d) 1 day T 3 followed by l day E 2. (e) 2 days E 2 alone. (f) 1 day T 3 followed by
2 days E 2. (g) 4 days E 2 alone. (h) 2 days T 3 followed by 2 days E 2. Arrows indicate pigmentation artefact surrounding the liver (see also Fig.
le,f). Bars represent 100 um. |
