Cell Biology

Reaching Out to the Other Side

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Science  09 Jan 2009:
Vol. 323, Issue 5911, pp. 186-187
DOI: 10.1126/science.323.5911.186b

Epithelial cells line the surfaces of the body, either in monolayers (simple) or in multiple layers (stratified). A third type of arrangement, referred to as pseudostratified, contains only a single layer of cells, but with their nuclei dispersed so as to give a laminated appearance. Shum et al. have used cell-specific labeling, confocal microscopy, and three-dimensional reconstruction to show that in pseudostratified epithelia, basal cells (on which the epithelium sits) extend projections that infiltrate the epithelial cell layer to make contact with the other (lumenal) surface. Such cells were observed in epididymis (both rat and human), rat coagulating gland (similar to the prostate), and rat trachea. Detailed analysis of the rat epididymis revealed that the frequency of these projections varied, with less than 10% of basal cells exhibiting this trait in proximal vas deferens and about 60% extending toward the lumen in more distal regions. The morphology of these projections varied, with some appearing just beneath tight junctions and some passing through the tight junctions at which three epithelial cells met. The authors detected angiotensin type 2 receptors (the renin-angiotensin system regulates male fertility) only in the basal cells (shown at left, green), and not in the clear cells (red) that acidify the lumen and keep sperm dormant during maturation and storage. Perfusion of rat epididymis with angiotensin II triggered the extension of proton pump-enriched microvilli from the clear cells and stimulated proton secretion. Thus, the authors suggest that the lumenal projections of the basal cells serve as sensors of hormones and transmit signals to neighboring cells within the epithelium. — NRG*

Cell 135, 1108 (2008).

  • *Nancy R. Gough is Editor of Science Signaling.

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