Anatomical and histological sex differences in the eye and its accessory tissues in Dutch belted rabbits

Rabbits are commonly used as laboratory animals in ocular toxicity studies. During development of ophthalmic drugs and medical devices, knowledge regarding sex differences of ocular anatomy and histology is important in the interpretation of toxicity data. However, limited information is available regarding ocular sex differences in rabbit eyes. Information on sex differences of rabbit eyes supports the justification of using single sex in the design of toxicity studies. We therefore investigated anatomical and histological ocular sex differences in Dutch belted rabbits aged 6 to 20 weeks which are frequently used in toxicity studies. Anatomical parameters of the eyeball (axial length, diameter, weight, volume), cornea (height, diameter), lens (thickness, diameter, weight, volume), and vitreous humor (weight, volume) were measured. Paraffin blocks of eye, meibomian glands, and lacrimal glands from males and females were sectioned and stained using hematoxylin and eosin, and compared. As the results, the anatomical parameters and their growth ratios showed no difference between males and females. In the histological comparison, although the development of glandular tissues was observed in both sexes according to aging, no sex differences were found. We concluded that there is no anatomical or histological sex differences in the eyes of Dutch belted rabbits from the period of post-weaning to sexual maturation.