title: Comparative morphology of the oocyte surface and early development in four characiformes from the São Francisco River, Brazil.
abstract: Early development from the egg fertilization to complete resorption of the yolk-sac is a critical period in the life cycle of teleost fish. Knowledge of this process provides essential parameters for aquaculture and identification of spawning sites in the wild. In the present study, a comparative morphological analysis of the oocyte surface as well as early development was performed in four commercially valuable species from the São Francisco River: Brycon orthotaenia, Leporinus obtusidens, Prochilodus argenteus, and Salminus franciscanus. Stripped oocytes, embryo, and yolk-sac larvae were analyzed by scanning electron microscopy (SEM) and histology. A set of 10 lectins was used for investigation of lectin-binding pattern in oocytes. In the four species, the outer layer of the zona radiata reacted to most lectins, indicating complex polysaccharides at the oocyte surface while no reactivity was detected in the inner zona radiata and yolk globules. Typical structural arrangements were recognized at the micropylar region by SEM. The four species showed nonadhesive eggs, short embryonic period (18-20 h at 24 ± 1°C), and poorly developed larvae at hatching. At 24 h posthatching (hph), larvae of the four species had neuromasts on the body surface. Rudimentary cement glands for larval attachment were identified on the cephalic region at 24 and 48 hph in B. orthotaenia and S. franciscanus, and following they were in regression. The time for whole yolk resorption varied among species from 48 to 120 hph, occurring earlier in S. franciscanus, followed by B. orthotaenia, P. argenteus, and L. obtusidens. The formation of the digestive tract and the mouth opening indicated initiation of exogenous feeding 24 h before complete resorption of the yolk. Together, our data indicate similarities in the early development among species that may be related to the life cycle strategies and phylogeny.
authors.affiliation: Departamento De Morfologia, Instituto De Ciências Biológicas, Universidade Federal De Minas Gerais, UFMG, Belo Horizonte, Minas Gerais, Brasil.
authors.forename: Kinulpe
authors.initials: K
authors.lastname: Honorato-Sampaio
authors.affiliation: Departamento De Morfologia, Instituto De Ciências Biológicas, Universidade Federal De Minas Gerais, UFMG, Belo Horizonte, Minas Gerais, Brasil.
authors.forename: Paula Suzanna
authors.initials: PS
authors.lastname: Prado
authors.affiliation: Estação De Hidrobiologia E Piscicultura De Três Marias, Companhia De Desenvolvimento Dos Vales Do São Francisco E Parnaíba CODEVASF, Três Marias, Minas Gerais, Brasil.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Departamento De Morfologia, Instituto De Ciências Biológicas, Universidade Federal De Minas Gerais, UFMG, Belo Horizonte, Minas Gerais, Brasil.|Programa De Pós-Graduação Em Zoologia De Vertebrados, Pontifícia Universidade Católica De Minas Gerais, PUC Minas, Belo Horizonte, Minas Gerais, Brasil.
authors.forename: Nilo
authors.initials: N
authors.lastname: Bazzoli
authors.affiliation: Departamento De Morfologia, Instituto De Ciências Biológicas, Universidade Federal De Minas Gerais, UFMG, Belo Horizonte, Minas Gerais, Brasil.
authors.forename: Elizete
authors.initials: E
authors.lastname: Rizzo
mesh_terms: D000818:Animals; D001938:Brazil; D060126:Characidae / Q000196:embryology* / Q000378:metabolism; D007814:Larva / Q000378:metabolism / Q000648:ultrastructure; D009865:Oocytes / Q000378:metabolism / Q000648:ultrastructure*; D015017:Yolk Sac / Q000378:metabolism / Q000648:ultrastructure
keywords: Brycon orthotaenia; Leporinus obtusidens; Prochilodus argenteus; Salminus franciscanus; lectin histochemistry; yolk-sac larvae