CONICET | Buscador de Institutos y Recursos Humanos

In 1651, William Harvey opened a real debate when he postulated that the egg is the origin of all life. The central pillar of Harvey´s theory sustains that all adults are already present in a smaller size in the egg. The frontispiece of his famous treatise attributed to Richard Gaywood shows Zeus holding an egg that releases small creatures as humans, others animals, and plants. The treatise concludes that no generation occurs without a primordial egg, representing the establishment of ex Ovo Omnia doctrine. Nowadays, evidence supports that both male and female gametes are essential for embryo development following sexual reproduction. Despite obvious differences in morphology and in scale, the oocytes carry out the same role in the development and still demonstrate the mystery of reproduction.