Abstract: Objective To study the correlation of the estrogen receptors α and β expression level with histopathology change in the meibomian gland of the ovariectomized rats. Methods Forty-eight adult female SD rats were randomly divided into three groups: the normal control group (16 rats),the sham operated group(16 rats) and the ovariectomized group (16 rats). After 12 weeks, all rats were killed and the tarsus tissues were excised. Expression of ERα and ERβ of meibomian glands were studied with immunohistochemistry. Histology of the glands was observed under a light microscope and a transmission electron microscope.The estrogen level of blood serum was examined with radioimmunoassay. Results There was no significant difference of the ERα expression level between the ovariectomized group and the control group (EM>P /EM>>0.05). The ERβ expression level in the ovariectomized group was weaker than that of the control group (EM>P/EM> < 0.01). ERα/ ERβ expression ratio was 1.06 in the control group and 1.83 in the ovariectomized group. The light microscope examination showed that the tissue and structure of meibomian gland acinar were abnormal in shape, cell size was smaller,and acinars were atrophy in the ovariectomized group.Under the transmission electon microscope, the gland acinar epithelia cells of the basal meibomian gland were small size, and the nuclei appeared irregular or kidney-like in shape. Transitional cells became small, the fatty drop reduced, and the mitochondrial swelling and mitochondrial cristae structural damage e.g., a vacuole or clouds changes, and a lot of medullary-like structure in the cytoplasm were existed in the ovariectomized group. Conclusion After ovariectomize

Key words: Meibomian gland, Estrogen receptor subtype, Dry eye, Ovariectomy, Histopathology, Transmission electron microscopy, Rat