Some people who deny that the human fetus is the subject of human rights try to make their case by pointing to brain death. They argue that the end of life is defined by the lack of brain activity, and hence the beginning of life requires brain activity, which de facto requires the presence of a brain, which is obviously not the case for the human embryo in the first weeks of its existence.
Neurobiology and anatomy professor Dr. Maureen Condic superbly dissects this argument in her article, "Life: Defining the Beginning by the End." She demonstrates that what is relevant in brain death is the dis-integration of the human being. That is, with the onset of brain death, the human organism is no longer a single, unified, self-directed, integrated organism, but simply a number of organs and organ systems co-habitating. It is not the loss of brain activity per se which is crucial, but rather the implication of that loss for the integration of the human. Death, Condic shows, is defined by the loss of integration; brain death merely indicates this disintegration.
Turning to the embryo, Condic demonstrates that although there is no brain, the embryo is in fact a single, unified, self-directed, integrated organism, and as such is morally and ontologically equivalent to an adult human being. The lack of a brain is irrevelant, in that the function of the brain -- to integrate various biological systems into a whole (human) being -- is found in the early embryo.
This really is a great article.