The oocyte is then implanted in the oviduct of a pseudopregnant animal. Fertilization occurs in the ampulla, the section of the oviduct that curves around the ovary. Cystovaries characterize most teleosts, where the ovary lumen has continuity with the oviduct. The fertilized eggs develop within the female's oviduct. Sperm is specifically stored between the uterine and infundibular components of the oviduct. The eggs are fertilised internally in the oviduct. Females possess a spermatheca, an ectodermal gland which opens into the oviduct. Some marsupial species are able to store sperm in the oviduct after mating. The sperm is preserved in the female's oviduct. The distal part of the oviduct, called ootype, is dilated. Other bird species will use porphyrins to pigment eggshells in the oviduct. This shape results from the egg being forced through the oviduct. Eggs pass from it into an oviduct. Up to nine larvae can develop in the oviduct at any one time. From here, a short oviduct passes to the vitelline duct.