MORFOGENIA LARVAL MICROANATÔMICA DO PEIXE-REI MARINHO <i>Odontesthes argentinensis</i> (ATHERINIFORMES, ATHERINOPSIDAE) DO RIO GRANDE DO SUL – BRASIL: ENTRE A ECLOSÃO E O 30º DIA

Abstract

(Larval microanatomy of marine silverside Odontesthes argentinensis from Rio Grande do Sul – Brazil) Larvae of Odontesthes argentinensis were cultured under controlled conditions in 15 liters tanks (temperature: 21-22,5ºC; salinity: 30-35‰; photoperiod: 13h light:11h dark; constant aeration and water renewing; density: seven larvae/liter and feeding: Artemia spp. nauplii) in the Estação Marinha de Aquicultura (EMA) from Universidade Federal do Rio Grande (FURG) to microanatomic and functional describe of the digestory system between hatching and 30º day-old. Histological and biometry samplings follow the ages: hatched (day zero=0D), 1D, 3D, 6D, 12D, 16D, 20D and 30D post-hatching with anesthesia with MS-222. To histology were fixed by 12h (0D≥age≤20D) and 24h (age=30D) in Bouin’s fluid to embedding in paraffin and permanent mounting in balsam, staining with Hematoxylin-Eosin under 7μm thickness microtomia in sagittal cut plane. At 0D life the species show: nervous system and striated skeletal muscle tissue (myomera) well differentiated; functional mouth; digestory tube in fast differentiation with a continuous lumen (together with fast hepatic and pancreatic formation) what permits a mixed nutrition (exogenous and endogenous); there is no anus formed; the pharyngeal cavity possess functional gills; the yolk sac is great and inhabit the greatest portion of the visceral cavity. 12D larvae show all internal no-gametal organ systems characterized. Until 30D O. argentinensis no develops stomach and pyloric ceca. The salinity can be an important factor to larval surviving although the tegument is present, respiratory and urinary systems were functional, what can denote a multifactorial mortality.