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Fig. 4. Islet mass and ß-cell proliferation is decreased in
Hhip–/– embryos (Hip1 in figure).
Islets were stained with antibodies directed against centrally located insulin
(green) and marginally located glucagon producing cells (red). Hhip function
is required for normal islet morphogenesis (A,B). Clusters of insulin- and
glucagon-positive cells form but are significantly smaller than the ones in
control embryos (wild-type or heterozygotes, compare B with A). To adjust for
differences in body mass, pancreas weight and islet area were divided by body
weight. (C, blue, control, n=6; red,
Hhip–/–, n=5; *P<0.05,
**P<0.01). Quantification of islet areas revealed a 45% reduction
that is more pronounced than the general loss of pancreatic tissue (C, blue,
control; red, Hhip–/–). The reduction in islet
mass is due to the loss of larger islets (>4000 µm2) while
the number of smaller islets (>4000 µm2) is maintained in
Hhip mutants (D, blue, control, n=5; red,
Hhip–/–, n=5; #no significant
difference, **P<0.01). Staining for the nuclear marker Ki-67
showed that proliferation of ß-cells at E18.5 is reduced by 39% (E, blue,
control, n=3; red, Hhip–/–,
n=5; *P<0.05). Changes in islet morphogenesis and
ß-cell proliferation are not due to incomplete cell differentiation
(F-I). ß-cells express mature markers, including Pdx1 (F,G; insulin,
green; Pdx1, red) and glucose transporter 2 (H,I; insulin, green; Glut2, red).
Error bars shown are ±s.d.
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