The mouse homozygous null mutant for a gene bfg always dies mid-gestation. Chimeric mice made of bfg null cells and wild-type cells have healthy pups. When the developing brain of these pups is examined, they have more than two hippocampi. Closer examination reveals bfg null cells at the centre of these supernumerary hippocampi.
Which of the following inferences can correctly be drawn from this experiment?
1
Wild type bfg function in the developing brain induces hippocampus specification in neighbouring cells.
2
Wild type bfg function in the developing brain suppresses hippocampus specification in neighbouring cells.
3
bfg function is completely cell autonomous.
4
bfg function is hippocampus specific.