We evaluated differences in the meibographic findings and immunohistochemical structures of mice, rats, and rabbits (commonly used in animal experiments).

Meibomian gland images were taken using an animal meibograph in mice, rats, and black and white rabbits (five of each animal).The size ratios of the upper and lower Meibomian glands were calculated. Afterm meibographic imaging, the eyes were cut sagittally or transversely and the histological structures were compared using hematoxylin-and-eosin (H&E) and immunohistochemical staining. In addition, the diameters of the central ducts and the areas of ducted glands and the acini were compared using image analysis software.

The meibographic findings were clearer in black rabbits than in the other animals. The upper to lower length ratio of the gland did not differ significantly among the three species. Histologically, no central duct epithelial cells were apparent in mice. The diameters of the central ducts and the areas of ducted glands and acini increased in the following order: mouse, rat, and rabbit. However, the Meibomian gland areas did not differ significantly between mice and rats. On immunohistochemical staining, the central ductal epithelium and the Meibomian gland acini were stained for cytokeratin 5 (CK 5) but only the central ductal epithelium was stained for cytokeratin 6 (CK 6).

The larger the experimental animal, the greater the sizes of the Meibomian gland ducts and acini. In addition, black rabbits yielded better gland images because contrast was enhanced. Compared with sagittal sections of Meibomian glands, transverse sections facilitated a better understanding of the structures of the central ducts and surrounding Meibomian gland acini.