カイコ卵の分割期における有糸分裂回数

概要

論文の詳細を見る
The number of nuclei was counted in the silkworm egg at 13 and 72 hours after oviposition to estimate the number of mitotic cleavage divisions to blastoderm formation. Eggs of C 108 (bivoltine) race kept at 25℃ after oviposition were used for the experiment. Histological preparations of the 13-hr-old eggs were made by the usual paraffin method using heidenhain iron hematoxylin staining. The 72-hr-old eggs (or just before the completion of pre-dormant stage) which had already completed nuclear divisions were dissected in a solution of 0.35% acetic acid and glycerin (13:1). Embryos were stained with acetocarmin for 10 min, covered with thin glass, and pressed gently to separate each cell. For both egg stages, the number of nuclei in all fields of the micrograph of each preparation was counted. The average number of nuclei in the 13-hr-old egg was calculated to be 1,985, of which 697 were destined to become the nuclei of embryonic and amnion cells. In the embryo of 72-hr-old eggs, the number of nuclei was counted to be 12,668. From these findings, we conclude that 11 divisions occur during the first 13 hours after oviposition at 25℃ and thereafter, at least 5 more divisions are required. Accordingly, the products of 16 mitotic cleavage divisions form the embryo (and/or blastoderm) with more than 104,000 but less than 208,000 nuclei.
社団法人日本動物学会の論文
1978-09-25