Spontaneous germinal matrix and intraventricular hemorrhage in prematurely born rabbits.

Spontaneous hemorrhage into the ventricles in premature babies is a major problem, and neither its cause nor its pathogenesis is understood. A model is presented for the study of germinal matrix and intraventricular hemorrhage in the preterm rabbit. This animal is particularly suitable because, like the human, 1) the maximal growth of the brain occurs perinatally; 2) there is an abundant germinal matrix near term, and by birth this is substantially reduced; 3) there is no rete mirabile; 4) the blood flow to the brain is via the internal carotid and vertebral arteries; 5) the maturation of the lungs is completed just before term; and 6) the rabbit pup can maintain a separate existence from the dam when delivered prematurely. Eight of 64 such animals were found to have developed spontaneous germinal matrix hemorrhage with or without rupture into the ventricles. Several physiological and chemical features characteristic of the premature rabbit are presented. The hemorrhage in the lagomorph might be a paradigm of that in infants, and its study may aid in the understanding of the pathogenesis of the process.