目的：研究早期子宫内膜腺癌及其癌前病变（腺瘤型增生及非典型增生）的超微结构，为早期鉴别诊断提供依据。方法：对８例子宫内膜腺瘤型增生，６例非典型增生，１２例Ⅰａ期子宫内膜高分化腺癌进行了扫描电镜及透射电镜检查。结果：腺瘤型增生细胞表面的纤毛、微绒毛明显增加，基膜完整，胞浆内初级溶酶体增加，细胞核异型性不明显。高分化腺癌细胞表面的纤毛、微绒毛明显减少且形态异常，基膜不完整，胞浆内初级溶酶体减少，次级溶酶体增多，粗面内质网和线粒体的形态及排列异常，细胞核异型性较明显，有的瘤细胞核内见核小体及核包涵体。非典型增生细胞表面及胞浆内的超微结构与高分化腺癌相似，但基膜基本完整，核内未见核小体及核包涵体。结论：诊断和鉴别早期子宫内膜腺癌及其癌前病变，电镜比光镜更有价值。 Objective: To study the ultrastructure of early endometrial adenocarcinoma and its precancerous lesions (adenomatous hyperplasia and atypical hyperplasia) and provide the basis for early differential diagnosis. Methods: Eight cases of endometrial adenoma hyperplasia, six cases of atypical hyperplasia and 12 cases of stage Ⅰa endometrial adenocarcinoma were examined by scanning electron microscopy and transmission electron microscopy. Results: The cilia and microvilli on the surface of adenomatous hyperplasia cells were significantly increased. The basement membrane was intact, the primary lysosomes in cytoplasm were increased, and the atypia was not obvious. On the surface of well-differentiated adenocarcinoma cells, the cilia and microvilli were significantly reduced and abnormal in morphology, the basement membrane was incomplete, the amount of primary lysosomes in cytoplasm was decreased, the number of secondary lysosomes was increased, the morphology and arrangement of rough endoplasmic reticulum and mitochondria were abnormal , More obvious atypia of the nucleus, some tumor nuclei and nuclear inclusions. The ultrastructure of atypical hyperplasia cells on the surface and cytoplasm is similar to that of well-differentiated adenocarcinoma, but the basement membrane is basically intact. No nucleosomes and nuclear inclusions are found in the nucleus. Conclusion: Diagnosis and differential diagnosis of early endometrial adenocarcinoma and its precancerous lesions are more valuable than light microscopy.