Generally speaking, green frog tadpoles that hatch early in the season will transform into frogs by mid-to late summer. Tadpoles that hatch late are likely to overwinter in their ponds and metamorphose late the following spring or early in the summer. Thus, the Green Frogs you see now with both legs and a tail spent the winter as tadpoles and are maturing now.
A specific process called “apoptosis” occurs as the tail is absorbed by the frog. It involves programmed cell death, and occurs in various forms in multicellular organisms. Humans experience apoptosis throughout their lives. It is responsible for the separation of fingers and toes in a developing embryo, as the cells between the digits undergo apoptosis and it is responsible for the death of between 50 and billion cells each day in the average human adult. Once it has begun, apoptosis cannot stop, and thus is a highly regulated process.
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