Occurs only in aquatic or very moist environments B. Internal fertilization 1. Sperm deposited within the body of the female, in close proximity to the reproductive tract 2. Fairly advanced, specialized structures are needed, along with appropriate behaviors and sexual cues 3. The only mode of fertilization that works in the terrestrial environment C. Protection of the embryo 1. External fertilization usually results in huge numbers of zygotes a. Proportion that survive, however, is usually quite small 2.
Internal fertilization results in fewer zygotes a.
These, however, may be protected for some time within the mother b. The basics 1. After they are mostly developed, they move on to the epididymis , where they are stored 5. During ejaculation, they pass through the vas deferens , which is simply another tube in the body 6. Fluids from these glands are important in activating the sperm, producing chemicals that counteract the acidity of the vagina, nourishing the sperm, and other functions 7.