title: Early ontogeny of the Atlantic halibut Hippoglossus hippoglossus head.
abstract: An ontogenetic sequence of Atlantic halibut Hippoglossus hippoglossus larvae, reared in intensive culture conditions, was cleared and stained and histologically processed to determine normal cranial chondrification for specimens ranging from 0 to 41 days post-hatch (dph). Twenty-six cranial cartilaginous structures were described, at daily intervals post-hatch. The ontogenetic trajectory, composed of alternating steps and thresholds, was interpreted as saltatory. In comparison with other flatfishes, H. hippoglossus exhibits delayed onset of chondrification. From 9 dph onwards, the ontogenetic trajectory resembles more than that of the turbot Psetta maxima than that of the common sole Solea solea or the summer flounder Paralichthys dentatus and winter flounder Pseudopleuronectes americanus. Hippoglossus hippoglossus with the gaping-jaw malformation, common in intensively cultured individuals of this species, were examined histologically. The reason larvae cannot close their mouth, as their yolk-sac resorbs, seems to be related to the fusion of the interhyal to the hyosymplectic and ceratohyal with which it is normally articulated.
authors.affiliation: Département de Biologie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada. richard_cloutier@uqar.qc.ca
authors.forename: R
authors.initials: R
authors.lastname: Cloutier
authors.forename: J
authors.initials: J
authors.lastname: Lambrey de Souza
authors.forename: H I
authors.initials: HI
authors.lastname: Browman
authors.forename: A B
authors.initials: AB
authors.lastname: Skiftesvik
mesh_terms: D000818:Animals; D002356:Cartilage / Q000033:anatomy & histology / Q000254:growth & development; D005432:Flounder / Q000033:anatomy & histology* / Q000254:growth & development*; D006257:Head / Q000033:anatomy & histology* / Q000254:growth & development*; D007568:Jaw / Q000033:anatomy & histology; D012886:Skull / Q000033:anatomy & histology / Q000254:growth & development; D013997:Time Factors