In multicellular organisms, division of the cytoplasm in meiotic cell division differs between the sexes. In female mammals (Fig. 11.13a), the cytoplasm is divided very unequally in both meiotic divisions. Most of the cytoplasm is retained in one meiotic product, a very large cell called the oocyte, which can develop into the functional egg cell, and the other meiotic products receive only small amounts of cytoplasm. These smaller cells are called polar bodies. In male mammals (Fig. 11.13b), the cytoplasm divides about equally in both meiotic divisions, and each of the resulting meiotic products goes on to form a functional sperm. During the development of the sperm, most of the cytoplasm is eliminated, and what is left is essentially a nucleus in the sperm head equipped with a long whiplike flagellum to help propel it toward the egg.