家蚕の生殖腺の發生に關する研究 : 第4報家蚕の後核燒灼卵に於ける生殖腺の形成

概要

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Cauterizing the posterior pole of silkworm eggs by a hot needle in the cleavage stage, in the early blastoderm stage, during the germ band formation, just before and after the stage of segmentation respectively, the gonad-formation in these eggs was observed at 96 hours after egg-laying (after blastokinesis) in section preparations. The results obtained are as follows: 1) If 8th segment is normal, the gonad is formed in 8th segment. When 8th segment is injured by cauterization, the gonad is found in 6th, 7th of 9th segment. However, in this case the gonad is not formed in the other segments except the above-mentioned ones. 2) The germ cells can also distribute outside of the above segments, but in this case they exist as free cells and there is no mark of the gonad. 3) The size of the gonad is decided by the sum of the germ cells included in it and the amount of its mesodermal elements. Therefore, on account of the irregular distribution of germ cells in each side, the size of the gonad becomes unequal in both sides. The defect of a part of the above-mentioned segments causes also the diminition of the size. From the latter fact it is suggestive that the presun ptive mesodermal elements of the gonad in the segments can not replenish the defect. 4) It is highly probable that though the gonad can be formed without the germ cells its formation will not be brought about by the existence of germ cells only.
社団法人日本動物学会の論文
1952-01-15