【摘要】 采用Bouin氏液固定、石蜡切片和苏木精-伊红染色方法,在光镜下对栉孔扇贝正常发育和6DMAP第二极体抑制型雌核发育二倍体卵在受精和第一、二次卵裂过程中的核相变化进行了详细观察。结果表明,正常发育卵内的雌、雄原核能融合为合子核,而雌核发育卵内的精核、雌核变化相当复杂。精核至少存在两种状态:(1)精核只在刚入卵时发生轻微膨胀,以后保持固缩状态,不膨大形成雄原核;(2)在第二次成熟分裂之后,精核再次去浓缩膨胀,但其体积并未达到正常雄原核的大小。在第一、第二次卵裂过程中,此精核不参与核分裂,以致密的染色质体(DCB)存在于两组分开的母本染色体之间,卵裂结束时滞留于两卵裂球的分裂沟上或进入其一的细胞质中。受精卵经6DMAP处理,雌核形成第二极体的过程受到有效抑制,导致雌核二倍化。此外,作者对实验中出现的多精入卵和多极分离现象进行了观察和分析。更多还原

【Abstract】 Artificial diploid gynogenesis, a form of all-female inheritance, was considered as one of the most effective techniques for the rapid establishment of inbred lines, mono-sexual broods or clones, as well as for examining sex-determination and gene-centromere recombination. Induction of gynogenetic diploid in many mollusks has been performed recently, but few cytological studies have depicted the fertilization and early cleavage events in eggs inseminated with ultraviolet(UV)-irradiated sperms. The aim of the experiment was expected to examine the differences of nuclear behavior on early development between normal and artificially induced gynogenetic diploid eggs of Chlamys farreri. In this study, a large number of gynogenetic diploids in Chlamys farreri were generated by activation of eggs with UV-irradiated spermatozoa and subsequent diploidization of the maternal chromosome set by blocking the second polar body extrusion. The optimal dose of UV light irradiation at intensity of 800 [WTBZ]μ[WTB1]W·cm -2·s for 50 s and the best treatment condition of 60 mg·mL -1 6-dimethylaminopurine(6-DMAP)for 20 min were obtained on the basis of the preceding trials. Then, to treat normal and gynogenetic diploid eggs of C. farreri fixed in Bouin’s fixative, nuclear changes were observed carefully under an optical microscope during fertilization and early cleavage. The results of cytological observation indicated that the female and male pronuclei of normal eggs fused into zygotonuceus, but their behaviors of gynogenetic diploid eggs were considerably complicated. The sperm nucleus of gynogenesis had at least two situations: One was that it kept dense and could not develop into male pronucleus, and another was that it expanded again after the second meiosis but did not reach its maximum as a normal male pronucleus. In the process of the first and second cleavages. The sperm nucleus of gynogenesis, which became a dense chromatin body (DCB), did not participate in the karyokinesis and was located between the two maternal chromosomes. At the completion of cleavage, DCB was seen either in the region of the first cleavage furrow or in the cytoplasm of one of the two blastomeres. Treatment with 6-DMAP, the formation of the second polar body was inhibited effectively and diploid female pronucleus was formed. In addition, the phenomena of polysperm and polyspindles in the experiment were also observed and analyzed.更多还原