Reduction or Absence of the Pituitary Corticotrope Lineage Results in Attenuated Cell Cycle Rhythms (A) Expression of pituitary markers in rx3 mutants. Whole-mount in situ hybridizations for pit1, growth hormone (gh), prolactin (prl), the glycoprotein hormone alpha subunit (α-gsu), and proopiomelanocortin (pomc) (6 dpf), with ventral views through the jaw cartilages, rostral up. Domains of pomc expression are indicated by arrows (arcuate nucleus), arrowheads (anterior pituitary), and asterisks (posterior pituitary). strong, strong rx3 mutants; weak, weak rx3 mutants; wildtype, wild-type siblings. (B–D) Quantification of BrdU incorporation in the lia (B), aal (C), and pit1 (D) mutants. Mean numbers of BrdU-positive nuclei determined as described in Figure 1 are indicated for each time point for mutants (blue) and siblings (red). Error bars show the 95% confidence interval of the mean; asterisks indicate statistical differences between mutant and wild-type values as determined by the Mann-Whitney test: *, p < 0.05; **, p < 0.01; ***, p < 0.001. Pooled results from two (B), five (C), and four (D) independent experiments are shown. (E) Scheme illustrating the pituitary lineages that are lacking (bracketed) in different pituitary mutants: lia and pia mutants lack all pituitary lineages. aal retains the lactotropes and lacks all other lineages. In pit1, only gonadotropes and corticotropes/melanotropes are present, and lactotropes, thyrotropes, and somatotropes are absent.
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