van Beek M E, Davids J A, de Rooij D G
Radiat Res. 1986 Jul;107(1):11-23.
Colony formation by surviving spermatogonial stem cells was investigated by mapping pieces of whole mounted tubuli at intervals of 6 and 10 days after doses of 0.75 and 1.50 Gy of fission neutron irradiation. Colony sizes, expressed in numbers of spermatogonia per colony, varied greatly. However, the mean colony size found in different animals was relatively constant. The mitotic indices in large and small colonies and in colonies in different epithelial stages did not differ significantly. This finding suggests that size differences in these spermatogenic colonies are not caused by differences in growth rate. Apparently, surviving stem cells start to form colonies at variable times after irradiation. The number of colonies per unit area varied with the epithelial stages. Many more colonies were found in areas that during irradiation were in stages IX-III (IX-IIIirr) than in those that were in stages IV-VII (IV-VIIirr). After a dose of 1.50 Gy, 90% of all colonies were found in areas IX-IIIirr. It is concluded that the previously found difference in repopulation after irradiation between areas VIII-IIIirr and III-VIIIirr can be explained not by differences in colony sizes and/or growth rates of the colonies in these areas but by a difference in the number of surviving stem cells in both areas. In area XII-IIIirr three times more colonies were found after a dose of 0.75 Gy than after a dose of 1.50 Gy. In area IV-VIIirr the numbers of colonies differed by a factor of six after both doses. This finding indicates that spermatogonial stem cells are more sensitive to irradiation in epithelial stages IV-VII than in stages XII-III. In control material, spermatogonia with a nuclear area of 70-110 micron2 are rare. However, especially 6 days after irradiation, single cells of these dimensions are rather common. These cells were found to lie at random over the tubular basement membrane with no preference for areas with colonies. It is concluded that the great majority of these cells were not or do not derive from surviving stem cells. These enlarged cells most likely represent lethally injured cells that will die or become giant cells (nuclear area greater than 110 micron2).
通过对经0.75 Gy和1.50 Gy裂变中子照射后间隔6天和10天的整个生精小管切片进行绘图，研究了存活的精原干细胞的集落形成情况。以每个集落中的精原细胞数量表示的集落大小差异很大。然而，在不同动物中发现的平均集落大小相对恒定。大、小集落以及处于不同上皮阶段的集落中的有丝分裂指数没有显著差异。这一发现表明，这些生精集落的大小差异不是由生长速率差异引起的。显然，存活的干细胞在照射后的不同时间开始形成集落。单位面积的集落数量随上皮阶段而变化。在照射期间处于IX - III期（IX - IIIirr）的区域中发现的集落比处于IV - VII期（IV - VIIirr）的区域中多得多。在1.50 Gy剂量后，所有集落的90%出现在IX - IIIirr区域。得出的结论是，先前发现的VIII - IIIirr区域和III - VIIIirr区域照射后再增殖的差异，不是由这些区域中集落大小和/或集落生长速率的差异来解释，而是由这两个区域中存活干细胞数量的差异来解释。在XII - IIIirr区域，0.75 Gy剂量后发现的集落数量是1.50 Gy剂量后的三倍。在IV - VIIirr区域，两种剂量后集落数量相差六倍。这一发现表明，精原干细胞在IV - VII上皮阶段比在XII - III阶段对辐射更敏感。在对照材料中，核面积为70 - 110平方微米的精原细胞很少见。然而，特别是在照射后6天，这些尺寸的单个细胞相当常见。发现这些细胞随机分布在管状基底膜上，对有集落的区域没有偏好。得出的结论是，这些细胞中的绝大多数不是或并非源自存活的干细胞。这些增大的细胞很可能代表将死亡或变成巨细胞（核面积大于110平方微米）的致死性损伤细胞。
