Retse

Retse, also known as retes or rete mirabile, is a biological term describing a complex network of blood vessels. This anatomical structure is characterized by its branching and rejoining, forming a mesh-like arrangement. The primary function of a rete is to facilitate the exchange of substances between blood and tissues, or to modify blood flow and pressure.

One notable example of a rete is found in marine mammals like whales and dolphins. In these animals, retia in their flippers and fins help to regulate body temperature. As warm blood from the core circulates to the extremities, it passes through the rete, where it transfers heat to the cooler blood returning from the surface. This countercurrent heat exchange mechanism minimizes heat loss to the cold ocean environment, conserving the animal's core body temperature.

Another significant rete is located at the base of the brain in many vertebrates, including humans, known as the rete mirabile of the brain. This structure plays a role in regulating blood pressure and oxygen supply to the brain. It can act as a buffer, smoothing out pulsatile blood flow from the heart and ensuring a more consistent delivery of oxygen and nutrients to the delicate brain tissue. In some species, it may also help protect the brain from sudden changes in blood pressure. The specific composition and function of retia can vary considerably across different species and their ecological niches.