目的  根据肾脏发生发育规律，探讨毛细血管袢期肾小球（capG）中毛细血管的体积密度变化规律。   方法  取发生发育多时间点的胚胎及生后早期小鼠肾脏，制备石蜡切片，采用内皮细胞标记物CD34免疫组织化学染色，结合体视学网格系统，测量CD34阳性表达的内皮细胞及其围成的毛细血管占肾小球的体积密度。   结果  根据肾小球的形态学及足细胞排列形式，将capG分为早、中、晚3期，capG中期又分为中早期和中晚期。除capG早期由于肾小球形状复杂无法测量外，中早期内皮细胞阳性的毛细血管袢的体积密度为(35.95±6.45)%，中晚期为(58.36±6.30)%，capG晚期体积密度为(79.89±5.21)%，作为对照的成熟期为(93.61±1.96)%。此外，不同发育时间点及相同发育期的肾小球毛细血管袢的体积密度保持恒定。   结论  肾小球发育过程中反映其有效滤过面积的毛细血管袢占肾小球的比例呈显著递增趋势，该结果为肾小球发育的评估提供了参数依据。

Objective  To describe quantitatively the development of the capillary loop stage glomerulus (capG) with respect to the volume density of capillaries in the glomerulus based on the morphogenesis of the kidney.   Methods  The kidneys were obtained from mice at various developing time points and prepared for paraffin sections. The volume density of CD34 positive endothelial cells and surrounded capillary lumen in glomeruli was measured using a combination of immunohistochemical staining and the stereological grid system.    Results  The capG was divided into early, middle, and late phases, and middle phase capG was subdivided into early-middle and late-middle phases, according to the morphology of developing glomeruli and the arrangement of podocytes. As result, the volume density of capillary loops in early phase capG could not be measured due to the complex “glomerular” shape. The volume density of capillary loops increased from (35.95±6.45)% in the early-middle phase capG, to (58.36±6.30) % in the late-middle phase capG, and to (79.89±5.21) % in the late phase capG, compared to (93.61±1.96) % in the mature glomerulus. Furthermore, the volume density of capillary loops remained constant at same stage even though at different developmental time points.    Conclusion  This study demonstrated a significantly increased volume density of capillary loops with the kidney development. In addition, the results provide a descriptive and reliable parameter for the evaluation of glomerular development.