Human amniotic epithelial cells are morphologically homogeneous: enzymehistochemical, tracer, and freeze-substitution fixation study

Abstract

We examined the fine subcellular morphology of human amniotic epithelial cells and attempted to answer the question as to whether amniotic epithelial cells consist of heterogeneous or homogeneous cells, which has long been controversial. Study subjects were fetal membranes from pregnant women (n=18) who abdominally gave birth to healthy infants at term (37.9±0.7 weeks of gestation, mean±sd). The methods employed were transmission electron microscopy, enzymehistochemistry, tracer permeability analysis, and freeze-substitution fixation. The labelings for acid phosphatase, cytochrome c oxidase, and CA ++ ATPase were seen in the lysosomes, mitochondria, and lateral plasma membranes, respectively. The staining distribution pattern of these three enzymes and the morphology of the organelle highlighted by these enzymehistochemistry did not differ among cells. Freeze-substitution fixation revealed that intercellular spaces in the amniotic epithelial cells were narrower than previously thought, but the tracers (horse radish peroxidase and lanthanum nitrate) fully entered these spaces. There were no variations in the tracer permeability among cells. All cells from freeze-substitution fixation exhibited the same morphological features. From these morphological viewpoints, we conclude that human term amniotic epithelial cells consist of a homogeneous cell population.

Stem cell therapy to protect and repair the developing brain: a review of mechanisms of action of cord blood and amnion epithelial derived cells

“…The innermost layer of the human amnion is 8–12 μm thick and consists of a single layer of homogeneous cuboidal epithelial cells, so-called hAECs (Hebertson et al, 1986; Iwasaki et al, 2003). hAECs display many characteristics of both embryonic and pluripotent stem cells, with the potential to differentiate into a range of cell types (Ilancheran et al, 2007; Parolini et al, 2008).…”

Differential response to hepatic differentiation stimuli of amniotic epithelial cells isolated from four regions of the amniotic membrane

“…Morphological and functional heterogeneity of hAEC isolated from different regions of the human amniotic membrane (hAM) is still debated. While most reports consider the hAM in toto, very few studies have attempted to address this issue, and results are so far limited and sometimes conflicting …”