Rete mirabile in mouse retina?

• Published in: Acta ophthalmologica (Oxford, England) Vol. 89; no. s248
• Main Authors: RUBERTE, J, MENDES‐JORGE, L, RAMOS, D, LOPEZ‐LUPPO, M, NACHER, V, NAVARRO, M, CARRETERO, A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2011; Wiley Subscription Services, Inc
• Subjects: Arterioles; Body weight; Capillaries; Carotid arteries; Carotid artery; Glomerulus; Hypoxia; Immunohistochemistry; Kidney; Kidneys; Oxygen; Oxygenation; Pressure; Retina; Sensory neurons; Veins
• ISSN: 1755-375X; 1755-3768
• DOI: 10.1111/j.1755-3768.2011.4454.x

Purpose One possible definition for rete mirabile, the “wonderful net”, is a capillary network interrupting one arteriole, as happens in kidney. In a glomerulus, the afferent and efferent arterioles are communicated by a capillary tuft. It is generally accepted that in mouse retina, capillaries communicate directly arterioles with venules. However, this must be difficult in a tissue where normally there is not concordance between the number of arterioles and veins. In the current study, we explored the presence of retia mirabilia in mouse retina which could explain the mismatch between retinal arterioles and venules. Methods Retinas from C57BL6 and CD1 mice were used. After partially clamping of the common carotid arteries, hypoxia was detected using the Hypoxiprobe‐1 Kit (Chemicon). Mice were intravenously injected with 60 mg pimonidazole/kg body weight in phosphate‐buffered saline. Pimonidazole specifically binds to proteins in hypoxic cells at an oxygen pressure equal to or lower than 10 mmHg. Thirty minutes after injection animals were euthanized and pimonidazole binding proteins were detected in the retina by immunohistochemistry. Results Direct capillary connections between retinal arterioles were found in C57BL6 and CD1 mice, indicating the presence of retia mirabilia. No venules were found between arterioles in the rete mirabile areas. In order to know if these retia mirabilia have some function in retinal oxygenation, partially clamping of common carotid arteries was performed and hypoxia was detected in the retina using the Hyposiprobe‐1 Kit. Interestingly, rete mirabile areas were less hypoxic than conventional capillary areas. Conclusion There are retia mirabilia in mouse retina and these vascular structures could be important in retinal oxygenation.