Figure 1.

Cellular distribution of fluorescein isothiocyanate (FITC)-labeled formaldehyde-treated serum albumin 24 h after injection. Arrows point to accumulation of fluorescence in hagfish (a, high endothelium of the radial artery of the gills); lamprey (b, cavernous body, which is a branch of the afferent artery of the gill); cod (c, endocardium); salmon (d, endothelial cells lining blood sinusoids in trunk kidney); and lizard and rat (e and f, sinusoidal liver endothelial cells). [Scale bars, 50 μm (a and b), 25 μm (c and d), and 10 μm (e and f).]