In relation to humans, we ought to note that in males the primary spermatocyte undergoes meiosis to form four sperm cells; in females the cytoplasm is distributed unequally during cytokinesis I and II. Thereby, one ovum is produced alongside of two or three polar bodies. As a result, the ovum has ample cell "materials" (ribosomes, mitochondria, enzymes...) for the embryo.