GFP-tagged Pom1 has been shown to create a gradient in elongated cells as characterized in Figure 1.
The longer loop of Henle in juxtamedullary nephrons create a hyperosmolar gradient that allows for the creation of concentrated urine.
Interestingly, animals with a need for very concentrated urine (such as desert animals) have very long loops of Henle to create a very large osmotic gradient.
The movement of protons creates an electrochemical gradient across the membrane, which is often called the proton-motive force.
When clouds move inland from over the ocean, heavy water rains out first and lighter water further inland, creating a stable gradient that can be mapped.
The resulting change in composition throughout the polymerization creates an inconsistent gradient along the polymer.
The explanation is relatively straightforward; the glucose slowly diffuses out of the capillary into the surrounding liquid, creating a gradient of sugar concentration.
The efflux of protons from the mitochondrial matrix creates an electrochemical gradient (proton gradient).
It also creates a gradient which induces water to flow out of cells and increases blood pressure.
Thus, these molecules create a gradient of BMP-4 along the dorsal/ventral axis of the mesoderm.