Structure and function of placental exchange surfaces in goodeid fishes (Teleostei: Atheriniformes)

ABSTRACT Cover illustration. Species of goodeid fish have evolved reproductive strategies involving intraovarian gestation, early evacuation of nearly yolk‐exhausted embryos from the ovigerous tissue into the ovarian cavity, placental matrotrophy during intraluminal gestation, and the birth of highly developed fry. The cover image shows a cross section of the gravid ovary of Xenotoca eiseni (see paper by Schindler, pp. 992–1004). —This issue of the Journal of Morphology presents three review papers on the evolution of viviparity and fetal nutritional adaptations. See also a comprehensive collection of papers in our virtual issue on “Fetal Nutritional Adaptations”.