Fascis mirabilis a set of prallel arterial and venous capillaries in the gas gland of some gas bladders that , using the countercurrent principle , increases gas tensions in the blood , and enables the gland to secrete gas into the gas bladder .

微血管束在一些气鳔的气腺里一组平行的动脉及静脉微血管，依据逆流原理，在血液增加气体分压，而使腺体能够泌出气体进入气鳔。