目的 定量研究大鼠从出生至12月龄脾脏主要结构的发育情况。 方法 从同群正常雄性SD大鼠中，在不同发育阶段（1d和1、3、6、12个月）随机抽选动物，每个年龄组6～7只。取完整的脾脏，切取组织块制作甲基丙烯酸树脂包埋切片，经过碘酸-雪夫试剂和苏木素染色后用体视学方法定量研究脾内主要组织结构的总体积。 结果 从1d至1月龄，大鼠脾脏体积增长了6.7倍，从1月至3月又增长了2.0倍，从3至12月只增加了39%。脾脏在1日龄已形成动脉周围淋巴鞘，1月形成边缘区，3月形成脾小结，且脾血窦里充满血液。3～12月龄脾内白髓、红髓所占体积比例稳定，分别为23%～27%、67%～70%。 结论 大鼠脾脏在3月龄前生长快速，发育成熟，之后仍继续生长，但变化不明显。

Objective To quantitatively study the first year development of key structures in the rat spleen. Methods Animals (6-7 per age group) were randomly sampled from a same cohort of normal male Sprague-Dawley rats at different phases of development -1 day and 1, 3, 6 and 12 months. The whole spleen was excised and tissue blocks were obtained for preparation of methacrylate embedded sections. The sections were stained with periodic acid-Schiff’s reagent and hematoxylin and the total volumes of key histological structures in the spleen were quantitatively studied using stereological methods. Results From the age of 1 day to 1 month, the splenic volume increased 7.7-fold; from 1 month to 3 months, it increased 3.0-fold; and from 3 to 12 months, it increased by 39% only. At 1 day of age the periarteriolar lymphoid sheath was formed in the rat spleen; at 1 month the marginal zone was formed; and at 3 months the splenic follicle was formed and blood was filled in the splenic sinus. At 3 to 12 months, the volume percentages of the white pulp and the red pulp in the spleen became stable, being 23%-27% and 67%-70%, respectively. Conclusion The rat spleen develops rapidly and reaches maturity by 3 months of age, with some continual growth but small changes afterwards.