Here is a link to Patrick Lee’s essay discussing the book by Samuel and Maureen Condic. Here is a brief summary from Lee’s essay.
In Human Embryos, Human Beings, A Scientific and Philosophical Approach philosopher Samuel Condic and Neurobiologist Maureen Condic advance a careful and detailed case for the proposition that a human being comes to be at fertilization, and refute the main arguments to the contrary. Along the way they clarify the concepts of substance, substantial form, soul, organism, and final and formal causality.