Fill in the Blanks Reproductive systemOnline version A Great game to learn the reproductive system by Chastity Grimes 1 Spermatogenesis cytoplasm secondary epididymis sperm 46 74 chromosomes male 23 tubules transported chromosomes , the origin and development of the cells within the male reproductive organs , the testes . Within the walls of the , also , are many randomly scattered cells , called Sertoli cells . One immature germ cell takes as long as days to reach final maturation , and during this growth process there are intermittent resting phases . The primary sperm cells then develop somewhat by increasing the amount of ( substances outside of the nucleus ) and structures called organelles within the cytoplasm . n the nucleus of the primary sperm cells there are ; in each of the sperm cells there are only , as there are in the egg . Once the sperm has matured , it is through the long seminiferous tubules and stored in the of the testes until it is ready to leave the body .