Pizer, M.*; Wray, G.A.: The Evolution and Development of Left-Right Asymmetry in Echinoderms Echinoderms have a bilaterally symmetrical larva that becomes left-right asymmetric when adult structures begin to develop. These structures form primarily on the left side of the larva, eventually producing a pentaradially symmetrical adult. This unusual symmetry transition is one of the most […]

SEAVER, E.C.*; PAULSON, D.; IRVINE, S.Q.; MARTINDALE, M. Q.: Sequence and developmental expression of the engrailed gene in the polychaete Chaetopterus The number of times a segmented body plan has evolved in the metazoa is a currently debated issue. We are interested in understanding whether the annelids and arthropods share a common segmented ancestor and […]

deMaintenon, M.J.: Patterns of reproductive system development in the caenogastropods; systematic and evolutionary implications. The reproductive system is one of the most complex and variable of gastropod organ systems, and is often also the last organ system to develop. The level of anatomical variation of the reproductive system, coupled with its late development, renders it […]

Golenberg, E.M.: Floral Developmental Regulation and Sexual Lability in Spinach In dioecious, cultivated spinach, Spinacia oleracea, the presence or absence of reproductive organs is determined by organ primordia initiation rather than by degeneration of existing organ primordia as found in maize, sorrel, and campion. Male and female flowers differentiate morphologically early in floral morphogenesis (stage […]

NEDERBRAGT, A.J.*; DICTUS, W.J.A.G.; VANLOON, A.E.: Conserved Gene Networks in Development: The Engrailed and Dpp Homologues in Molluscan Shell Development During Drosophila development the engrailed/hedgehog/decapentaplegic gene network functions in setting up boundaries between different compartments, e.g. between anterior and posterior compartments in imaginal discs. Here, engrailed is expressed in cells on one side of the […]

FREEMAN, G.: A Developmental Basis for the Cambrian Explosion: Evidence from Extant Brachiopods Paleontological evidence indicates that a large number of new animal phyla, in addition to classes and orders within phyla, were first observed during the Cambrian. One possible basis for the genesis of new morphologies during this period may have been the ease […]

GILBERT, S.F.*; LOREDO, G.A.; BRUKMAN, A.; TUAN, R.: Studies in Turtle Shell Development: Osteogenesis of an Evolutionarily Novel Structure The turtle shell is an evolutionary novelty, a development of the osseous skeleton unique among vertebrates. The turtle shell is composed of a dorsal carapace, a ventral plastron, and a lateral bridge. The carapace contains fifty […]

JERNVALL, J.*; KER�NEN, S.V.E.; THESLEFF, I.: Quantifying evolutionary modification of development in mammalian molar topography Mammalian dentition is characterized by complex and diverse molar cusp patterns and subtle changes in molars are usually the earliest morphological evidence of modern orders in the fossil record. However, the exact ways that embryonic patterning of tooth shapes could […]

STEWART, J.R.*; HEULIN, B.: Ontogeny of the Extraembryonic Membranes in Oviparous Viviparous Lizards, Lacerta vivipara. Lacerta vivipara is a reproductively bimodal species with allopatrically distributed viviparous and oviparous populations. Morphological, ecological and genetical similarities among populations indicate that oviparous and viviparous populations are closely related and diverged recently. This species provides a rare opportunity among […]

CARL, T. F.; HANKEN, J.*: Neural-crest derivation of the ossified skull in amphibians revealed by vital labeling with GFP. Derivation of most if not all of the ossified skull from the embryonic neural crest is an accepted axiom of contemporary developmental biology. Yet, this “fact” is based on direct empirical results involving just one species […]