If one follows 150 primary oocytes in an animal through their various stages of oogenesis, how many secondary oocytes would be formed?

150 secondary oocytes would form. Primary oocytes, or immature ova, will not split when becoming secondary oocytes. This division process only occurs when spermatocytes are developing. When spermatocytes reach their secondary phase, they will develop into two secondary spermatocytes per cell.