Experimental hydranencephaly in the ovine fetus |
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Authors: | E M Wintour M Lewitt A McFarlane K Moritz S Potocnik S Rees K Tangalakis |
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Institution: | (1) Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria 3052, Australia, AU;(2) Department of Anatomy, University of Melbourne Parkville 3052, Victoria, Australia, AU |
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Abstract: | Hydranencephaly is defined as the replacement of a previously normal brain, in whole or in part, by membranous fluid-filled
sacs. The etiology is not well understood, and the time course of development is unknown. Fifteen ovine fetuses were chronically
cannulated and had both carotid arteries ligated at 100 days of gestation (term is 145–150 days). They were killed at 1 (n = 4), 2 (n = 6) and 4 (n = 5) weeks post-surgery, and the findings compared with those of 25 age-matched controls. By 2 weeks post-surgery the entire
cerebral hemispheres and diencephalon had been replaced by fluid closely resembling cerebrospinal fluid. The choroid plexus,
pituitary and brain stem remained outwardly normal, but the cerebellum showed signs of damage. Fetuses maintained normal values
for blood gases and hematocrit up to 4 weeks post-surgery, and grew normally. Light microscopy of the brain stem showed significant
losses of cell populations in the medulla by 4 weeks. Vascular casting and acute blood flow studies in an additional group
of fetuses showed that the entire brain was perfused via the vertebral-occipital anastomosis immediately after acute bilateral
carotid clamping, but that the blood flow rate was insufficient to maintain adequate oxygen delivery.
Received: 4 August 1995 / Revised, accepted: 30 November 1995 |
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Keywords: | Ovine Fetus Hydranencephaly |
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