Ontogenia digestiva y visual de la merluza europea, Merluccius merluccius durante la fase endo-exotrófica

Abstract

Histo-physiological events during the European hake, Merluccius merluccius larvae development are showed. During lecitotrophic phase (0-5 dph), the mouth and the anus were closed. Larvae 4 dph present well different iated and pigmented eyes and the notochord, trunk and dorsal part of the digestive tract was spotted with melanophores. When mouth opening and endogenous and first exogenous feeding coexisted (from 6 dph), most systems, organs and tissues (digestive, liver, exocrine pancreas, eyes, swim bladder), were sufficiently well differentiated, and it may be compatible with an adequate growth and development from this time onwards. The yolk-sac assures, via periblast or yolk syncytial layer, the nutritive supply of the larvae during organogenesis, morphogenesis and growth. At 10 dph, remaining yolk-sac and functional liver are connect ed; stomach gastric glands are not differentiated, but lipid absorption in anterior intestine and pinocytotic up take and posterior intracellular protein digestion within posterior intestine are detected. Swimbladder and visual activity (cones and rods)) are well developed and enough functional in hake larvae 10 dph.