Nine female nulliparous laboratory New Zealand white rabbits (2–4.75 years) with a pituitary gland adenoma of prolactin-secreting cells (prolactinoma) and markedly elevated serum prolactin developed non-neoplastic cystic changes in the mammary gland parenchyma associated with intraluminal papillary epithelial proliferations and lactational activity; the mammary gland lesions were diagnosed as dysplasia [37]. Here, PRL is linked to pituitary gland adenoma.