Question

Which of the following events does not occur during the first 8 weeks of development?

A) beginning of ossification
B) formation of a functional cardiovascular system
C) presence of all body systems
D) myelination of the spinal cord

Answer 1

During the first 8 weeks of development, myelination of the spinal cord does not occur; this process starts in the third trimester and continues postnatally.

Step-by-step explanation:

The question concerning events that do not occur during the first 8 weeks of development in the human embryo is asking which of the specified developmental milestones is incorrect for that time frame. The correct answer is myelination of the spinal cord. While other key events, such as beginning of ossification, formation of a functional cardiovascular system, and presence of all body systems, do begin to take place during this period, myelination of the spinal cord starts later in development. Myelination primarily occurs during the third trimester and continues after birth, aiding in the proper transmission of nerve impulses within the developing nervous system.