Hairlessness does not influence growth retardation in nude mice. Computer image analysis study

Ossification in 4-week-old nu/nu and nu/+ BALB/c and BFU mice was studied by X-ray analysis and by measurement of the thickness of the proximal tibial growth cartilage using CUE 4 Olympus computer image analysis. Not only altered architecture but also a significantly thinner proximal tibial growth plate was observed in athymic nu/nu as opposed to nu/+ and BFU mice. On the other hand, no significant differences were found between nu/+ and BFU littermates. Higher X-ray density of tail vertebrae was observed in nu/+ and BFU than in nu/nu mice. This comparison between athymic nu/nu and hairless euthymic BFU mice indicates that altered postnatal ossification in nude mice is not caused by hairlessness, but is due to other (immunological or endocrinological) differences.