Lagos-Cabré Raul, Moreno Ricardo D
Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331010 Santiago, Chile.
Reproduction. 2008 Apr;135(4):471-8. doi: 10.1530/REP-07-0389. Epub 2008 Feb 22.
The process of mammalian spermatogenesis involves both mitosis and meiosis at the same developmental age. Most previous studies have focused on mitotic spindle orientation during development, but not during meiotic division. Therefore, we asked whether there is a difference between mitotic and meiotic germ cell spindle orientation during rat spermatogenesis. Our results showed that mitotic spindles of spermatogonia were mainly oriented with angles ranging from 60 to 90 degrees, perpendicular in relation to the basement membrane of the seminiferous tubules. On the other hand, meiotic spindles showed a random orientation. Nocodazole treatment (at a concentration that depolymerizes only astral microtubules) induced a significant increase in cells with an angle between 0 and 30 degrees (parallel) in relation to the basement membrane. Meiotic spindles did not show a significant change in their orientation after the Nocodazole treatment. Therefore, our results suggest differences between the mechanisms controlling positioning and orientation of mitotic and meiotic spindles during rat spermatogenesis. It seems that a phylogenetically conserved programme controls the mitotic spindle orientation in organisms ranging from worms to mammals.
哺乳动物精子发生过程在同一发育阶段涉及有丝分裂和减数分裂。以往大多数研究集中在发育过程中的有丝分裂纺锤体定向，而非减数分裂过程中的定向。因此，我们探讨了大鼠精子发生过程中有丝分裂和减数分裂生殖细胞纺锤体定向是否存在差异。我们的结果表明，精原细胞的有丝分裂纺锤体主要以60至90度的角度定向，相对于生精小管的基底膜呈垂直方向。另一方面，减数分裂纺锤体呈随机定向。诺考达唑处理（浓度仅能解聚星体微管）导致与基底膜呈0至30度（平行）角度的细胞显著增加。诺考达唑处理后，减数分裂纺锤体的定向未显示出显著变化。因此，我们的结果表明大鼠精子发生过程中控制有丝分裂和减数分裂纺锤体定位与定向的机制存在差异。似乎一个系统发育上保守的程序控制着从蠕虫到哺乳动物等生物体中的有丝分裂纺锤体定向。
