Two Morphological Types of Placentæ in the Raccoon

Abstract

THE literature on the placenta of the raccoon (Procyon lotor L.) is extremely sparse and, to the best of our knowledge, placentation in this carnivore is mentioned only by Watson¹, Rau², Mossman³ and Amoroso⁴. The three last-named authors have all quoted aspects of the original contribution by Watson, and it seems, therefore, that knowledge of the raccoon placenta has been based on Watson's early observations. The material at his disposal was, unfortunately, limited to one gravid uterus which contained but one conceptus and, as Watson states, the material was not in the best condition. Observations, in this laboratory, on four gravid uteri involving 17 conceptuses have revealed certain understandable misinterpretations and omissions in Watson's paper. Furthermore, the discovery by one of us (R. F. S. C.) of a hitherto unreported but prominent placental organ associated with the more commonly mentioned zonary placenta in the raccoon re-focuses attention on the so-called hæmatomata of the carnivore placenta.