The Placental Mammal's Ova: An Egg in Which Yolk Is Absent
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3 min read
Placental mammals are born with a finite number of ova at birth, and their eggs are a key example of one in which egg yolk is absent. This is a sharp contrast to the eggs of birds, reptiles, and fish, which are all defined by their rich, yolky interiors. The absence of yolk in these tiny eggs is an evolutionary adaptation.
