Cerebral ischemia in the developing primate fetus.

The common carotid arteries and jugular veins of fetuses of dated rhesus monkey pregnancies were ligated at different times during the last 2/3's of gestation. Fetuses that survived were delivered surgically at term and their brains examined pathologically. The findings obtained demonstrated the following principles: 1. Production of ischemia of the anterior cerebral circulation by bilateral ligation of the common carotid arteries and jugular veins prior to the end of the first half of gestation (82 days) produced brain abnormalities in all instances. 2. Ligation of the common carotid arteries and jugular veins during the middle 1/3 of gestation (55-110 days) produced 1) extensive focal tissue destruction restricted to the ischemic territory in 6 of 12 fetuses and 2) abnormal brain development in 3 of 12 fetuses. 3. Ligation of the common carotid arteries and jugular veins early during the middle 1/3 of gestation favored the occurrence of cerebral dysgenesis or brain malformation while late during the middle 1/3 it favored focal tissue destruction. In the earlier cases of blood vessel ligation the focal tissue destruction resembled hydranencephaly. 4. Production of ischemia of the anterior cerebral circulation by ligation of the common carotid arteries and jugular veins during the last 1/3 of gestation (greater than 110 days) produced no gross or microscopic brain abnormalities.