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Experimental hydranencephaly in the ovine fetus
E M Wintour1, M Lewitt, A McFarlane
1Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
Acta Neuropathologica
|January 1, 1996
Summary
Hydranencephaly, a brain condition, can develop rapidly in fetal sheep after carotid artery ligation. Within two weeks, cerebral hemispheres are replaced by fluid, with brain stem damage occurring later.
Area of Science:
- Neuroscience
- Developmental Biology
- Fetal Surgery
Background:
- Hydranencephaly involves the brain being replaced by fluid-filled sacs.
- The exact cause and developmental timeline of hydranencephaly remain unclear.
Purpose of the Study:
- To investigate the developmental time course of hydranencephaly in a fetal sheep model.
- To understand the pathological changes following carotid artery ligation in utero.
Main Methods:
- Ovine fetuses underwent chronic cannulation and bilateral carotid artery ligation at 100 days of gestation.
- Fetuses were analyzed at 1, 2, and 4 weeks post-surgery, with comparisons to age-matched controls.
- Vascular casting and acute blood flow studies were performed to assess cerebral perfusion.
Main Results:
- By 2 weeks post-surgery, cerebral hemispheres and diencephalon were replaced by cerebrospinal fluid-like fluid.
- The cerebellum showed damage, and the brain stem exhibited significant cell loss in the medulla by 4 weeks.
- While fetuses maintained normal blood gases and growth, vertebral-occipital anastomosis perfusion was insufficient to maintain adequate oxygen delivery.
Conclusions:
- Bilateral carotid artery ligation in ovine fetuses induces rapid hydranencephaly-like changes.
- The vertebral-occipital anastomosis compensates partially but inadequately for cerebral blood flow, leading to hypoxic injury and cell death.