Final answer:
Primary oocytes are formed from oogonia during fetal development and are arrested in prophase I of meiosis until puberty, after which they can develop into secondary oocytes and polar bodies.
Step-by-step explanation:
The primary oocytes of a human female are formed during fetal development from ovarian stem cells called oogonia, which undergo mitosis to form primary oocytes. However, these primary oocytes are arrested in prophase I of meiosis until puberty. At puberty, influenced by anterior pituitary hormones, the primary oocytes can then resume and finish the first meiotic division, forming secondary oocytes and polar bodies, where the polar body typically degenerates. This process occurs within the follicles of the ovaries. The secondary oocytes then undergo a secondary arrest at the metaphase II stage, which will only resume and complete if fertilization occurs, resulting in a fertilized egg with the full complement of chromosomes.