Erectile tissue is a type of spongy tissue found in certain parts of the body, primarily in the penis and clitoris. This tissue can fill with blood, leading to an increase in size and rigidity, which is essential for sexual arousal and function. In the penis, erectile tissue is composed of two main structures called the corpora cavernosa and the corpus spongiosum. When a person becomes sexually aroused, signals from the nervous system cause blood vessels to dilate, allowing more blood to flow into these areas, resulting in an erection.