A moderate number of delicate CGRP-immunoreactive (CGRP-IR) varicose nerve terminals were found at the adventitia-media border of the sexually mature porcine ovarian artery by means of a routine single immunolabelling technique. Additionally, a pharmacological analysis was performed of the function fulfilled by alpha-CGRP and its C-terminal fragment (Tyr27) alpha-CGRP(27-37) in the porcine isolated ovarian artery, collected on days 8-13 of the oestrous cycle. It was shown that alpha-CGRP (10(-8) M) caused a decrease in the perfusion pressure of the porcine isolated ovarian artery of 16% (p < 0.05), while (Tyr27) alpha-CGRP(27-37), added at the same concentration, reduced perfusion pressure by 13% (p > 0.05). Thus, we concluded that alpha-CGRP released from perivascular terminals may cause relaxation of the ovarian artery and, furthermore, that the potency of this action is dependent on the length of the chain of this peptide produced during the deactivation of the molecule by tissue proteases.