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Multiple simultaneous intervillous space pressures recorded in several regions of the hemochorial placenta in relation to functional anatomy of the fetal cotyledon

1968; Elsevier BV; Volume: 102; Issue: 8 Linguagem: Inglês

10.1016/0002-9378(68)90403-1

1097-6868

S. R. M. Reynolds, U. Freese, J Bieniarz, R. Caldeyro‐Barcia, C. Méndez-Bauer, Luis Escarcena,

Prenatal Screening and Diagnostics

Three to four probes were inserted under cinefluoroscopy into areas of the IVS of the rhesus monkey placenta. They were seen to lie in or near the central cavities of fetal cotyledons, which are the sites of entry of maternal blood into IVS, or in more peripheral parts of the fetal cotyledon. When possible, samples of blood were withdrawn for oxygen content determinations. Pressures were found to be highest in or near the central cavity of a cotyledon, so that the gradient diminished radially from, and above, the cavity toward the subchorial lake. When the uterus contracted, the IVS pressure rose equally near the center and the periphery of the cotyledon. In intermediate positions, pressures rose relatively more and approached the highest central pressure in the cotyledon, and the gradient of pressure toward the periphery increased. In short, uterine contractions force blood from the center of the fetal cotyledon in the manner that fluid is moved in pistonless pumps. Insofar as limitations of blood sampling techniques permitted, resulting largely from the physiologic factors involved, suggestion of a similar gradient in oxygen content of intervillous space blood was found, decreasing from the center of cotyledons toward their peripheries. These results support the hypothesis of a central entry of maternal arterial blood into the IVS of a cotyledon, fetal villous structures seem to determine a pressure gradient toward the periphery in the intracotyledonary space, and Braxton Hicks contractions increase the movement of blood from cotyledon centers throughout the IVS.