In oogenesis, what are the products after meiosis I?

• A. Ootid and second polar body
• B. Secondary oocyte and first polar body
• C. Zygote and polar body
• D. Primary oocyte and second polar body

Answer: (B)

In oogenesis, meiosis I converts a primary oocyte into a large secondary oocyte and a small first polar body. The primary oocyte is diploid with replicated chromosomes; during meiosis I, homologous chromosomes separate, producing two haploid cells with duplicated chromosomes. Cytoplasm is divided unequally, so the secondary oocyte receives most of the cytoplasm for future development, while the first polar body gets little and typically Degenerates. This is why the product after meiosis I is a secondary oocyte along with the first polar body. Fertilization then triggers meiosis II in the secondary oocyte, producing an ovum and a second polar body, and a zygote forms only after fertilization.