Morphology of canine placental sites after induced embryonic or fetal death

Abstract

Although spontaneous and medically induced canine embryonic or fetal death and “resorption” are clinically well documented, morphological studies of these processes are still missing. The objective of this study was therefore a detailed morphological investigation of canine placental sites after embryonic or fetal death. In five pregnant beagle bitches, embryonic or fetal death was induced by cloprostenol and cabergoline or by aglepristone. Two dogs served as untreated controls. Between Days 30 and 33 of gestation, the bitches were ovariohysterectomized, placental sites were fixed and examined by different methods. Morphological features of placental sites after both treatments were similar, finally leading to a complete disappearance of the placental labyrinth. Although there was an increase in the number of cells in the glandular chambers (superficial endometrial glands) expressing lysozyme after induced fetal death, signs of phagocytosis were absent in these cells, and no increased infiltration of maternal stroma by macrophages (compared to normal placental sites at the same time of gestation) occurred. We inferred that fetal and placental tissues were lysed, but no phagocytosis by genuine or “functional” macrophages was detectable. Further investigations are needed for a more detailed understanding of the morphological processes occurring after embryonic or fetal death in the dog.