Reproductive senescence, fertility and reproductive tumour profile in ageing female Han Wistar rats

65 animals (62.5%) showed adenomas and/or pituitary hyperplasia in the pituitary gland at necropsy. The pituitary tumours were likely to be prolactin secreting that give rise to pseudopregnancy and mammary tumours, demonstrated by the fact that 43/65 (66%) of the affected animals had histopathological signs of these conditions. Multiple corpora lutea were found in 61% of all animals at time of termination. Only one uterine tumour was seen in this study probably due to lack of persistent oestrus seen in these animals.