Heifetz Y, Yu J, Wolfner M F
Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703, USA.
Dev Biol. 2001 Jun 15;234(2):416-24. doi: 10.1006/dbio.2001.0246.
Drosophila melanogaster mature oocytes in ovaries are arrested at metaphase I of meiosis. Eggs that have reached the uterus have released this arrest. It was not known where in the female reproductive tract egg activation occurs and what triggers it. We investigated when and where the egg is activated in Drosophila in vivo and at what meiotic stage the egg is fertilized. We found that changes in the egg's envelope's permeability, one feature of activation, initiate during ovulation, even while most of the egg is still within the ovary. The egg becomes impermeable as it proceeds down the oviducts; the process is complete by the time the egg is in the uterus. Cross-linking of vitelline membrane protein sV23 also increases progressively as the egg moves through the oviducts and the uterus. Activation also triggers meiosis to resume before the egg reaches the uterus, such that the earliest eggs that reach the uterus are in anaphase I. We discuss models for Drosophila egg activation in vivo.
果蝇卵巢中的成熟卵母细胞停滞在减数分裂I中期。到达子宫的卵子则解除了这种停滞状态。此前尚不清楚卵子激活发生在雌性生殖道的哪个部位以及触发激活的因素是什么。我们研究了果蝇体内卵子何时何地被激活，以及卵子在减数分裂的哪个阶段受精。我们发现，卵子激活的一个特征，即卵子包膜通透性的变化，在排卵期间就开始了，即便此时卵子的大部分仍在卵巢内。卵子在沿着输卵管下行的过程中变得不透性；当卵子进入子宫时，这一过程完成。随着卵子在输卵管和子宫中移动，卵黄膜蛋白sV23的交联也逐渐增加。激活还会在卵子到达子宫之前触发减数分裂恢复，因此最早到达子宫的卵子处于减数分裂I后期。我们讨论了果蝇体内卵子激活的模型。
