EN
Placentomes were obtained immediately after calving from 34 cows with retained placenta and 19 cows with normal placental release. All cows had a normal duration of pregnancy. In placentomes from cows without retained placenta the lack of cryptal epithelium and a small number of binucleate cells was noted. In the group with retentio secundinarum, 73.6% of the cows had delayed maturation of placenta (presence of cryptal epithelium and numerous binucleate cells), 17.6% had placentitis (infiltration of leucocytes) while 8.8% showed proliferation of connective tissue of caruncles. Thus, the major cause of disturbances in placental release was the delayed maturation of placenta.