What is the weakest part of a developing, adolescent long bone?

The weakest part of a long developing and adolescent bone is called growth cartilage (epiphyseal plate)

Explanation:

Both children's bones and adults' bones are at risk of injury. However, in the case of bones in a child, they are subject to an injury known as a growth cartilage fracture or epiphyseal plate. These growth cartilages are areas that are in full development in the vicinity of long bones. Its function is to help establish the length and shape of the bone in the process of maturation. The growth of a long bone happens from the end next to the growth cartilage. In adulthood, these growth cartilages are strengthened forming the bone.

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