[Environment and genetics of endocrine polyoncoses. An aging bull model].

An old bull, it is said by those who know, can have his troubles. Included among these are vertebral osteosclerosis and ankylosing spondylosis--this stiffening up limite, rather than accentuates, the value and reproduction potential of a stud bull past prime. But associated with these abnormalities--and not seen in age-matched cows of comparable breeds--are fascinating endocrine neoplasms that might suggest a pattern that could be productive as a model of human hereditary endocrine abnormalities. Adjacent to the thyroid gland in other vertebrates are ultimobranchial bodies, that are incorporated into the lateral thyroid lobes in primates as the parafollicular "C-cells" of the thyroid. These are the cells in man that give rise to medullary thyroid cancer and are associated with calcitonin secretion, useful as a tumor marker. In aging bulls of whatever breed, nearly half exhibit abnormality of these ultimobranchial bodies: 20% show hyperplasia, and 30% have frank neoplasia. These ultimobranchial tumors appear in bulls passing 6 1/2 years in age, and are absent in young bulls and all cows of any age. Calcitonin can be demonstrated in the ultimobranchial tumors from bulls, and secretion is stimulated by calcium infusion, though serum calcium remains normal. The ultimobranchial tumors themselves can range from hyperplasia through adenoma to metastasizing carcinoma--in fact, representing one of the commoner cattle cancers. Parathyroid glands taken from bulls with these ultimobranchial tumors initially show evidence of inhibited secretory activity and morphologic atrophy, but later go on to develop hyperplasia and, eventually, autonomy.(ABSTRACT TRUNCATED AT 250 WORDS)