Rete mirabile
A rete mirabile ( Latin , German "wonder network"; plural: retia mirabilia ) is a branching of an artery into a network of the finest arteries, which then does not unite to form a vein , but in turn to form an artery.
In all vertebrates , such miracle nets occur in the glomerula of the kidney . Here an arteriole ( arteriola glomerularis afferens ) branches into a fine capillary network ( glomerulum ), which in turn gathers in an arteriole ( arteriola glomerularis efferens ). As is usual in the circulatory system, the latter then turns into a capillary network that drains into veins. In the case of the glomerula, this miracle net is used for ultrafiltration of primary urine from the blood .
Miracle meshes also occur in a few other arteries:
- in articulated ungulates on the internal carotid artery
- in ruminants on the external ophthalmic artery ( arteria ophthalmica externa )
- in cats on the maxillary artery ( arteria maxillaris )
- with Loris on the hands and feet
- with fish ( Physoclisten ) to fill the swim bladder
The functional significance of these formations has not yet been clarified for many species.
In tuna and sharks , miracle nets serve as countercurrent heat exchangers for thermoregulation . The swimming muscles in these animals generate a lot of warmth, the miracle nets keep the warmth in the core of the body and the vital organs have a higher temperature than the surrounding water. However, the miracle nets consist of relatively thick-walled vessels and do not allow gas exchange. With the Physoclists they support the enrichment of the swim bladder with oxygen and with other fish species the oxygen supply to the retina.
There are also venous miracle networks as branches of the portal vein in the liver and the pituitary portal vein in the anterior lobe of the pituitary gland .
literature
- Uwe Gille: Cardiovascular and immune system, Angiologia. In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine. 2nd, revised and expanded edition. Enke, Stuttgart 2008, ISBN 978-3-8304-1075-1 , pp. 404-463.