In 1656, Ferdinand II of Tuscany invited him to the professorship of theoretical medicine at the University of Pisa. There Malpighi began his lifelong friendship with Giovanni Borelli, mathematician and naturalist, who was a prominent supporter of the Accademia del Cimento, one of the first scientific societies. Malpighi questioned the prevailing medical teachings at Pisa, tried experiments on colour changes in blood, and attempted to recast anatomical, physiological, and medical problems of the day. Family responsibilities and poor health prompted Malpighi's return in 1659 to the University of Bologna, where he continued to teach and do research with his microscopes. In 1661 he identified and described the pulmonary and capillary network connecting small arteries with small veins. Malpighi's views evoked increasing controversy and dissent, mainly from envy and lack of understanding on the part of his colleagues.
In 1656, ferdInAnD iI of tuscany INVitEd HiM To the proFEssOrshiP of thEorEtiCAl MediCine at tHe UniVersiTY of PIsa. theRe malpIghi beGan his LIFelOng frIEndship WiTh GiovAnni BoReLLi, mAThemAticiaN aNd naTuraLIst, whO wAS A pRoMInent supportEr of THe AccADemiA DEl ciMeNTo, ONe OF tHe fIrst scieNtiFiC sOciETIes. MAlpIghi questioNeD THE prevAiling Medical tEAchiNGS aT pisa, TrIed expErIMents on cOlour cHanges iN BlOod, and attemptED To recasT anATomicaL, PHysioloGIcal, and mEDicAl prOblems of The day. famIly rEsponSibIlities aNd POor healTh promPted malpighi's retUrn IN 1659 tO the UnIVeRsitY of BolOgna, wheRe hE contInued To teach aND do researCh with hIs mIcrosCopEs. iN 1661 he IDENtifieD ANd descrIbed the pulmonarY and capIlLaRY NETwOrk connEcting sMalL ArtErIEs with SmAll vEins. malPighi's views EVoKeD INcREaSiNg conTroversy ANd DiSseNt, MaInLy froM envy And lack of uNderstaNDIng on the part of hIS cOlLeAgues.