We are pleased to share the following study on the rete mirabilia which may be of interest to members of the list. Retia mirabilia: Protecting the cetacean brain from locomotion-generated blood pressure pulses M. A. LILLIE<https://www.science.org/doi/10.1126/science.abn3315#con1>, A. W. VOGL<https://www.science.org/doi/10.1126/science.abn3315#con2>, S. G. GERARD<https://www.science.org/doi/10.1126/science.abn3315#con3>, S. <https://www.science.org/doi/10.1126/science.abn3315#con4> RAVERTY<https://www.science.org/doi/10.1126/science.abn3315#con4> AND R. E. SHADWICK<https://www.science.org/doi/10.1126/science.abn3315#con5> SCIENCE 22 Sep 2022 Vol 377, Issue 6613 pp. 1452-1456 ABSTRACT Cetaceans have massive vascular plexuses (retia mirabilia) whose function is unknown. All cerebral blood flow passes through these retia, and we hypothesize that they protect cetacean brains from locomotion-generated pulsatile blood pressures. We propose that cetaceans have evolved a pulse-transfer mechanism that minimizes pulsatility in cerebral arterial-to-venous pressure differentials without dampening the pressure pulses themselves. We tested this hypothesis using a computational model based on morphology from 11 species and found that the large arterial capacitance in the retia, coupled with the small extravascular capacitance in the cranium and vertebral canal, could protect the cerebral vasculature from 97% of systemic pulsatility. Evolution of the retial complex in cetaceans-likely linked to the development of dorsoventral fluking-offers a distinctive solution to adverse locomotion-generated vascular pulsatility. https://www.science.org/doi/10.1126/science.abn3315#.YzEeqtZPtcs.mailto Stephen Raverty Veterinary Pathologist Animal Health Center 1767 Angus Campbell Road Abbotsford, BC Canada V3G2M3 Stephen.Raverty@gov.bc.ca Phone 778-666-0516 [cid:image001.png@01D8D172.C9C69020]
