A simple columnar epithelium<span> is a </span>columnar epithelium<span> that is uni-layered. In humans, a simple </span>columnar epithelium<span> lines most </span>organs<span> of the digestive tract including the stomach, small intestine, and large intestine. Simple columnar epithelia line the </span>uterus<span>.</span>
<span>undergo a dramatic decline in size, possibly to a stable level at or below 1,800 individuals.</span>
It is called a watershed.