Nelson-Rees W A, Hoy M A, Roush R T
Chromosoma. 1980;77(3):263-76. doi: 10.1007/BF00286052.
Embryogenic mitoses, mitoses in females and spermatogenesis are described in the predatory mite Metaseiulus occidentalis (Nesbitt). At 22 degrees C, egg development lasts approximately 4 days. Six chromosomes are seen in mitotic metaphases and anaphases of 0--24 h eggs. Toward the end of this period some embryo squashes have patches of cells containing nuclei which are partially heteropycnotic. These patches of cells apparently increase in size with the age of the embryo. In approximately 1/2 of all 24--48 h-old eggs they encompass all or most cells of the embryo. In these embryos metaphases involved 6 chromosomes, anaphases 3. Either prior to, or following metaphase, a pairing of chromosomes appeared to take place to form 3 units which resembled meiotic diplotene chromosomes where there is opening out between homologues. At metaphase, two sets of 3 chromosomes were slightly differentially stained. One, designated the H set, was darker and slightly more contracted than the other, the E set. At anaphase, 3H and 3E chromosomes segregated in a reductional division retaining the differential contraction until telophase. No cytokinesis appeared. The H set appeared to remain contracted while the E set decontracted to assume the appearance of an interphase nucleus. Both of these entities, side-by-side, created the partially heteropycnotic nucleus mentioned above. The H set then appeared to be excluded from the cell. Mitotic meta- and anaphases involving 6 chromosomes were noted in female deutonymphs. Spermatogenesis appeared to encompass an equational division of 3 chromosomes, which the formation of a binucleate spermatid. Two tail structures appeared juxtaposed at the edge of each spermatid and thereafter a separation into two individual sperms occurred.--While mitosis was not studied in known males, we believe that the embryos exhibiting heterochromatinization and elimination of chromosomes in most or all cells were in fact demonstrating parahaploidization.
在捕食螨西方盲走螨（Nesbitt）中描述了胚胎有丝分裂、雌性有丝分裂和精子发生过程。在22摄氏度下，卵的发育持续约4天。在0 - 24小时卵的有丝分裂中期和后期可见6条染色体。在此阶段末期，一些胚胎压片有细胞斑块，其中细胞核部分异固缩。这些细胞斑块显然随着胚胎年龄的增长而增大。在所有24 - 48小时龄的卵中，约有1/2的胚胎，这些斑块包含胚胎的所有或大多数细胞。在这些胚胎中，中期有6条染色体，后期有3条。在中期之前或之后，染色体似乎会配对形成3个单位，类似于减数分裂双线期染色体，同源染色体之间会展开。在中期，两组3条染色体的染色略有差异。一组称为H组，比另一组E组颜色更深且收缩程度略大。在后期，3条H染色体和3条E染色体在减数分裂中分离，直到末期仍保持差异收缩。未出现胞质分裂。H组似乎保持收缩状态，而E组解缩呈现间期核的外观。这两个实体并列形成了上述部分异固缩的核。然后H组似乎被排除在细胞之外。在雌性若螨中观察到涉及6条染色体的有丝分裂中期和后期。精子发生似乎包括3条染色体的均等分裂，形成双核精子细胞。在每个精子细胞边缘并列出现两个尾部结构，随后分裂成两个单独的精子。——虽然未对已知雄性的有丝分裂进行研究，但我们认为，在大多数或所有细胞中表现出异染色质化和染色体消除的胚胎实际上正在进行准单倍体化。
