An electron microscope study on spermatogenesis in Hymenolepis nana

Only on the basis of nuclear size, spermatogonia can be easily identified by their relatively large prominent nuclei. Further meiotic division occur resulting in primary spermatocytes. The nuclei become smaller, placed peripherally forming the spermatids. A membrane-bound clefts develop in the cytoplasm in the region of spermatid nuclei and that such clefts eventually enclose the elongated nuclei to become the plasma membrane of the sperm. There is a common general pattern of spermatogenesis in cestodes which follows the pattern typical of the platyhelminthes.