Submitted March 31, 2008
Returned for revision April 15, 2008
Accepted May 8, 2008
Pregnancy
Particulate Urban Air Pollution Affects the Functional Morphology of Mouse Placenta
Mariana Matera Veras *,
Nilsa Regina Damaceno-Rodrigues ,
Elia Garcia Caldini ,
Antonio A.C. Maciel Ribeiro ,
Terry M. Mayhew ,
Paulo H.N. Saldiva ,
and
Marisa Dolhnikoff
* To whom correspondence should be addressed. E-mail: verasine{at}usp.br.
Abstract
In humans, adverse pregnancy outcomes (low birthweight, prematurity, intrauterine growth retardation) are associated with exposure to urban air pollution. Experimental data have also shown that such exposure elicits adverse reproductive outcomes. We hypothesized that the effects of urban air pollution on pregnancy outcomes could be related to changes in functional morphology of the placenta. To test this, future dams were exposed during pre-gestational and gestational periods to filtered or non-filtered air in exposure chambers. Placentas were collected from near-term pregnancies and prepared for microscopical examination. Fields of view on vertical uniform random tissue slices were analysed using stereological methods. Volumes of placental compartments were estimated and the labyrinth analysed further in terms of its maternal vascular spaces, fetal capillaries, trophoblast and exchange surface areas. From these primary data, secondary quantities were derived: vessel calibres (expressed as diameters), trophoblast thickness (arithmetic mean) and total and mass-specific morphometric diffusive conductances for oxygen of the intervascular barrier. Two-way analysis of variance showed that both periods of exposure led to significantly smaller fetal weights. Pre-gestational exposure to non-filtered air led to significant increases in fetal capillary surface area and in total and mass-specific conductances. However, the calibres of maternal blood spaces were reduced. Gestational exposure to non-filtered air was associated with reduced volumes, calibres and surface areas of maternal blood spaces and with greater fetal capillary surfaces and diffusive conductances. The findings indicate that urban air pollution affects placental functional morphology. Fetal weights are compromised despite attempts to improve diffusive transport across the placenta.
Key words:
Environment •
Pregnancy •
Placenta •
Trophoblast •
air pollution
