Studies on the Maternal Inheritance of the Lethal Yellow in the Silkworm, Bombyx mori

II. Ovarian Transplantations

Abstract

Fifth-instar larve with genotypes +/lem^l and lem/lem^l, which had segregated from a cross between +/lem^l and lem/lem^l, were used as material. The ovaries of the larvae of both types were exchanged. Of 630 larvae thus operated upon, only 3 survived and had offspring.
The female moths produced from these larvae were mated with male moths of the genotype lem/lem^l. The eggs laid were incubated and larvae homozygous for lem^l gene were examined.
When the +/lem^l larvae were implanted with ovaries of lem/lem^l, the homozygous lem^l embryos which developed from the transplanted eggs hatched out, as the apparently normal ones do, as black-coloured larvae, but they changed into distinctly yellowish larvae which died immediately after the first moulting.
On the other hand, the lem^l homozygous larvae emerging from eggs laid by the lem/lem^l moth which had received a +/lem^l ovary by transplantation developed into yellowish-brown young larvae, then died within the egg.
From these results it may be concluded that the stage of death of the lethal larvae is not determined by the genotype of the embryo (+/lem^l or lem/lem^l) but by that of the mother's body in which the eggs develop.