In good time
When my daughter was born, I could not help but realise that she already had inside her what would participate in giving life, if she so chose, to a daughter or a son of her own. Given a little thought, it is an extraordinary state of affairs. My daughter's ovaries were already filled to the brim with a life-time's stock of egg cells, albeit not quite mature. As it so happened, my next child was a baby boy, and I knew he would only begin to produce germ cells at puberty and cease to produce them when his life comes to an end. It is a fundamental difference between the two sexes, which obviously entails very distinct physiological makeups. Notably, on an average, egg cells must remain healthy during the best part of two decades, at the very least in these parts of the world, before one, or two, or perhaps several more are actually fertilised. Fertility is hugely dependent on egg-cell fitness, which is why many mechanisms exist to protect not only an egg's integrity but also elemental macromolecules and organelles whose activities are temporarily arrested. One protein known as ZAR1, from Zygote ARrest 1, is at the heart of such a mechanism.
