Timing of Fetal Meconium Absorption by Amnionic Macrophages

ABSTRACT

This study sought to determine the time interval from fetal defecation to membrane staining and subsequent meconium uptake by amnionic macrophages. Pieces of external membranes were fastened to Teflon rings to create a well. The amnionic surface was exposed to meconium and amniotic fluid for 1 to 48 hours and analyzed microscopically for the presence of free meconium and meconium-laden amnionic macrophages. In each of the experiments, prior to the 12-hour time point, few meconium-laden macrophages were present in the membrane layers. A significant rise in the number of meconium-laden macrophages and a concomitant increase in staining intensity was noted in the membranes at 24 and 48 hours. Contrary to previous reports, our in vitro model of meconium incorporation into placental membranes demonstrated that significant numbers of meconium-laden macrophages were only observed after 24 and 48 hours.

KEYWORDS

Meconium - pigment-laden macrophages - placenta - transport kinetics

REFERENCES

• 1 Glantz J C, Woods J R. Significance of amniotic fluid meconium. In: Creasy R, Resnik R Maternal Fetal Medicine, Principles and Practice. Philadelphia; W.B. Saunders 1999
• 2 Manning F A, Harman C R, Morrison I, Menticoglou S M, Lange I R, Johnson J M. Fetal assessment based on fetal biophysical profile scoring. IV. An analysis of perinatal morbidity and mortality.  Am J Obstet Gynecol. 1990;  162 703-709
• 3 Altshuler G, Arizawa M, Molnar-Nadasdy G. Meconium-induced umbilical cord vascular necrosis and ulceration: a potential link between the placenta and poor pregnancy outcome.  Obstet Gynecol. 1992;  79 760-766
• 4 Sienko A, Altshuler G. Meconium-induced umbilical vascular necrosis in abortuses and fetuses: a histopathologic study for cytokines.  Obstet Gynecol. 1999;  94 415-420
• 5 Altshuler G. Some placental considerations related to neurodevelopmental and other disorders.  J Child Neurol. 1993;  8 78-94
• 6 Altshuler G. Placenta within the medicolegal imperative.  Arch Pathol Lab Med. 1991;  115 688-695
• 7 Miller P W, Coen R W, Benirschke K. Dating the time interval from meconium passage to birth.  Obstet Gynecol. 1985;  66 459-462
• 8 Furie M B, Naprstek B L, Silverstein S C. Migration of neutrophils across monolayers of cultured microvascular endothelial cells. An in vitro model of leucocyte extravasation.  J Cell Sci. 1987;  88(Pt 2) 161-175
• 9 Oh J Y, Rosow E, Bronzino J, Enderle J, Eisenfeld L. The design and development of a biosensor to measure the concentration of meconium in amniotic fluid.  Biomed Instrum Technol. 2001;  35 46-56
• 10 Dubowy R L, Feinberg R F, Keefe D L et al.. Improved endometrial assessment using cyclin E and p27.  Fertil Steril. 2003;  80 146-156
• 11 Vain N E, Szyld E G, Prudent L M, Wiswell T E, Aguilar A M, Vivas N I. Oropharyngeal and nasopharyngeal suctioning of meconium-stained neonates before delivery of their shoulders: multicentre, randomised controlled trial.  Lancet. 2004;  364 597-602
• 12 Fraser W D, Hofmeyr J, Lede R et al.. Amnioinfusion for the prevention of the meconium aspiration syndrome.  N Engl J Med. 2005;  353 909-917
• 13 Burgess A M, Hutchins G M. Inflammation of the lungs, umbilical cord and placenta associated with meconium passage in utero. Review of 123 autopsied cases.  Pathol Res Pract. 1996;  192 1121-1128