Jacquet P, de Saint-Georges L, Buset J, Baatout S, Vankerkom J, Baugnet-Mahieu L
Department of Radioprotection, CEN/SCK, Mol, Belgium.
Mutat Res. 1997 Jul 14;391(3):189-92. doi: 10.1016/s1383-5718(97)00071-5.
In female mammals, the immature oocyte is the germ cell most at risk, from the genetic point of view. We have previously shown that ovaries of newborn guinea pigs contain a great majority of immature oocytes and small numbers of maturing oocytes. At this time, all immature oocytes are in a typical diplotene stage, comparable to that of the human resting oocyte. Furthermore, the LD50 of the guinea pig oocytes is about 4 Gy, like that of human oocytes. Consequently, performing genetic studies on guinea pig oocytes irradiated just after birth constitutes a very useful approach to predict the mutational response of the human resting oocyte. Female guinea pigs were X-irradiated with 1 or 2 Gy within 24 h of birth, and their meiotically competent oocytes were collected and cultured to the metaphase I stage, 1 year after treatment, ensuring that all oocytes were at the immature stage at the time of irradiation. The proportion of oocytes that showed chromosome aberrations (breaks, fragments or interchanges) was only 1-2% Gy(-1). Although not definitive, these results provide support for a low risk in women from an exposure of the immature oocyte to low doses of radiation.
在雌性哺乳动物中，从未遗传角度来看，未成熟卵母细胞是最易受影响的生殖细胞。我们之前已经表明，新生豚鼠的卵巢中绝大多数是未成熟卵母细胞，只有少量成熟卵母细胞。此时，所有未成熟卵母细胞都处于典型的双线期，类似于人类静止期卵母细胞。此外，豚鼠卵母细胞的半数致死剂量约为4 Gy，与人类卵母细胞相同。因此，对出生后立即接受照射的豚鼠卵母细胞进行遗传学研究，是预测人类静止期卵母细胞突变反应的一种非常有用的方法。雌性豚鼠在出生后24小时内接受1或2 Gy的X射线照射，处理1年后收集其具有减数分裂能力的卵母细胞并培养至中期I阶段，确保所有卵母细胞在照射时都处于未成熟阶段。显示染色体畸变（断裂、片段或互换）的卵母细胞比例仅为1 - 2% Gy(-1)。尽管这些结果并非定论，但它们为未成熟卵母细胞暴露于低剂量辐射对女性造成低风险提供了支持。
