Morphometry of the Placental Exchange Area

Considering the placenta from the functional point of view as an exchange organ be­ tween mother and foetus it is noteworthy that placentas of all types have a common structural principle in that all placentas have structures enlarging the surface area avail­ able for exchange as is also the case with other organs with similar functions such as the lungs kidneys and intestine. It may therefore be assumed that a quantitative rela­ tionship must exist between the structure of the placenta and its function. Accurate information on this relationship could contribute to better understanding of the pla­ centa and of its function. The study of this relationship requires quantitative physio­ logical and morphological data. Detailed data on quantitative morphology (morphometry) are available mainly for the human placenta. Even these data however are rather sparse as far as the early sta­ ges of development are concerned because most-studies relate to full term placentas (see Aherne 1975; Bender et al. 1974; Laga et aI. 1973; Geissler et aI. 1972; Baur 1972; Cattoor 1967; Aherne and Dunnill 1966). We know of only a few morphomet­ ric studies concerned with placentas of other animal species. These studies relate to in­ vestigations on the development of the placenta of sheep (Stegeman 1974) and of cat­ tle (Baur 1972) and measurements carried out on full term placentas of the guinea­ pig (Millier et aI. 1967) and on full term placentas of various other species (Baur 1973).