Authors/Affiliations: Valeria Sofia Rivera Alvarado, Stephen Viviano, Engin Deniz (Department of Pediatrics, Yale School of Medicine, New Haven, CT)

Introduction: Understanding cerebrospinal fluid (CSF) circulation in the brain, especially during embryonic development, remains challenging due to the inaccessible cranial vault. In adult brains, glial cells and the para-vascular space have recently been proposed to form a pathway for CSF excretion called the glymphatic pathway. However, it is unknown how this system impacts CSF circulation during development.

Methods: Transparent Xenopus tadpoles were used to visualize neurodevelopment in real time due to easy access to the CNS. We injected fluorescent-labeled albumin into the ventricular space and tracked the CSF circulation at 1,2,3 and 24 hours after the injection. Simultaneously, albumin was also injected into the tadpoles’ hearts to delineate the CSF and cardiovascular pathways for better tracking. Finally, the heart and the lymphatic pumps were removed to examine their direct influence on CSF circulation and drainage.

Results: In Xenopus tadpoles CSF did not use the vascular routes to drain, as tracers in the ventricles and heart did not overlap. Interestingly, the ablation of the heart and the lymphatic pump did not immediately impact the CSF clearance from the brain, suggesting additional forces in play.

Conclusion: Xenopus is the first genetically tractable small animal model to study the glymphatic pathway in real-time. During the early stages of development, the brain establishes a comprehensive path for CSF drainage independent of cardiac and lymphatic forces. Further exploration of the role of this embryonic glymphatic pathway in brain development and its potential implications for congenital hydrocephalus remains a compelling avenue for investigation.

Acknowledgements: Special thanks to Dr. Engin Deniz for believing in my potential, for his mentorship and encouragement that pushed me beyond my limits. To Stephen Viviano, for his willingness to invest time and effort in nurturing my skills. To Dr. Marietta Vázquez and Dean Latimore for their support and the opportunities they provided me throughout the program. Project was supported by Novartis and Yale School of Medicine Summer Research Program in collaboration with Universidad Central del Caribe.

Keywords: Glymphatic pathway, Xenopus, Hydrocephalus, CSF