Signals from inner space

Advances in knowledge of mammalian physiology have been achieved through endocrine studies of sheep and deer. Such advances include the role of the pineal gland as the mediator between changes in daily photoperiod and melatonin secretion, plus the role of thyroid hormones, for controlling reproduction in seasonally breeding livestock. Antlers provide an example of post-maturity bone formation in a mammal and we have shown that additional hardening (mineralisation) of the antlers results from activation of nearby oestradiol receptors. Based on studies of sheep, C-type natriuretic peptide has emerged in spite of its name as an important adaptive signal for fetal well-being and may be an important regulator of brain function