背景:精原干细胞技术的快速发展为生殖工程带来了新希望,而在体外维持染色体数目及结构的稳定性是其使用的关键问题之一.目的:探索精原干细胞染色体G带显示技术及其影响因素,为如何鉴定培养状态下干细胞的染色体核型提供实验参考.设计:观察实验.单位:泸州医学院材料:实验于2004-03/2005-04在泸州医学院医学分子生物学实验室完成.生后10 d左右的昆明系小白鼠(雌雄均可)由泸州医学院动物科提供(许可证号:川实动管质第17号),低糖DMEM,10 mg/L丝裂霉素C,IMDM培养基,1×10-5 mol/L秋水仙素(磷酸缓冲液配置),7.5 mmol/L低渗氯化钾,甲醇:冰醋酸(3∶1)固定液,Giemsa染液,0.25%胰蛋白酶.方法:取小白鼠股骨骨髓,进行饲养层细胞的制备.取生后7～8 d左右雄性小白鼠睾丸并制成细胞悬液,调整细胞密度为3×105 L-1,接种到预先制备好的骨髓基质细胞饲养层上,细胞在37℃、体积分数0.05的CO2、70%湿度的二氧化碳培养箱中培养.待细胞生长到15～20 d时,吸出克隆细胞团,吹打分散后滴加秋水仙素处理4～6 h.收集细胞悬液,再经低渗处理后滴片染色.选择染色体分散良好,无重叠的分散中期的细胞进行记数,观察染色体形态.主要观察指标:骨髓基质及精原干细胞的培养及染色体显色与计数.结果:精原干细胞的核型与正常小鼠体细胞的染色体形态一致,染色体呈粒状、棒状,核型为20对,40条.在油镜下镜检可见3种染色体形态,一种呈高浓缩状态的染色体,可计数染色体总数,但不能显出带纹;第2种是已完全展开并铺于赤道板上的处于分裂中期的染色体,染色体总数和带纹显示都非常清楚;第3种是染色体已折转并向两极移动,并逐渐开始浓缩,染色体总数可以计数,带纹不能清楚显示.结论:小鼠精原干细胞染色体受到细胞所处的分裂时期、低渗处理的效果、滴片时细胞的分散程度及胰酶浓度及消化时间等因素的影响.%BACKGROUND:Rapid development of spermatogonial stem cells is the new hope for assisting reproductive technologies,and the stability of the number and structure of the chromosome cultured in vitro is one of the important factors in usage.OBJECTIVE: To study the influential factors on G-band exhibition in mouse spermatogonial stem cells, so as to offer a technology to identify karyotype of stem cells in culture.DESIGN: Observational experiment.SETTING: Luzhou Medical College.MATERIALS: The experiment was conducted in the Laboratory of Medical Molecular Biology, Luzhou Medical College from March 2004 to April 2005. 10 days old male and female Kunming mice were provided by Department of Animal of Luzhou Medical College (number of license No. 17 of experimental animal quality administration in Sichuan province).There were low-sugar DMEM medium, 10 mg/L Mitomycin-C, IMDM medium, 1 ×10-5 mol/L colchicines (PBS allocation),7.5 mmol/L KCL, fixative (mixture glacial acetic acid with methanol in 1:3), Giemsa staining solution and 0.25% zymine.METHODS: Bone marrow was aspirated from the thigh bone of mouse for feeder layer cells preparation. Cells from the male mice testis of 7-8 days after birth were prepared and made into cell suspension. After adjusting the cell density to 3×105 L-1, they were inoculated into the feeder layer of bone marrow stromal cells. Cells were cultured at 37 ℃ in CO2 incubator containing CO2 of 0.05 volume fraction and 70% humidity. The proliferation groups of stem cells cultured 15-20 days were selected, stirred and spread, and then treated with colchicine for 4-6 hours. Cell suspension was collected,and then stained after hypotonic treatment. The cells whose chromosomes were dispersed well and in metaphase were selected, and number of chromosomes was counted, and then the morphology of chromosomes was observed.MAIN OUTCOME MEASURES: Culture of bone marrow stromal cells and spermatogonial stem cells and coloration and count of chromosomes.RESULTS: The karyotype of spermatogonial stem cells was the same as the body cells of normal mouse, which showed granule or rod-shape. Karyotype was 20 pairs, 40 bars. Three kinds of chromosome morphology could be observed under oil immersion lens. The first type was condensed, which could be counted in total, but the band could not be seen.The second type was chromatosome that spread completely in the center of equatorial plate and were in metaphase. In this phase, total numbers and band were seen clearly. Last type-chromosomes had already folded and moved towards two poles and concentrated gradually, the total number of chromosomes could be counted, but bending could not be seen clearly.CONCLUSION:Many factors can affect the karyotype of spermatogonial stem cells, including the phase of cell division,effect of hypotonic solution, diffusion of the cell when dropping slides, concentration of trypsin and digestion time, etc.
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