TEM of arteriole in dense connective tissue, human. An arteriole is a small diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. Arterioles have muscular walls (usually only one to two layers of smooth muscle) and are the primary site of vascular resistance. Connective tissue (CT) is one of the four types of biological tissue that support, connect, or separate different types of tissues and organs in the body. Connective tissue is found in between other tissues everywhere in the body, including the nervous system. Magnification @5000x, 8x10 print.