Dynamic study of the extraembryonic vascular network of the chick embryo by fractal analysis

Fractal analysis is widely used in many scientific fields, including the st udy of vascularization. It is a convenient method that defines the complexi ty of natural structures. The chorioallantoic membrane of the chick embryo is a standard experimental model for the study of vasculogenesis and angiog enesis. The aim of this investigation was to demonstrate that fractal geome try is more appropriate than any other method to describe and analyse the e volution of a vascular network, i.e. the extraembryonar vascular network of the chick embryo. We used an original methodology to evaluate the complexi ty of this network in the first stages of embryo development (day 3 until 6 ). We demonstrated an increase of fractal dimension, indicating an increasi ng complexity of the vascular tree, until an asymptotical value of about 1. 70 at day 4. The fractal approach is more accurate than other usual semi-qu antitative or quantitative methods evaluating the complexity of a growing v ascular tree. (C) 1998 Academic Press.