Identification of novel genes involved in the development of the sword and gonopodium in swordtail fish



COVER PHOTOGRAPH: Bony fin rays of the gonopodium, an intromittent organ, of the male swordtail fish, Xiphophorus helleri. Distal skeletal elements are differentiated into hook-like structures that facilitate efficient sperm transfer during internal fertilization. From Offen et al., Developmental Dynamics 238:1674–1687, 2009. © 2009 Wiley-Liss, Inc.