| Abstract |
Quality in fish culture is divided into two categories: the consumer defined quality and the producer defined quality. The quality characteristics that concern the consumer are wholesomeness, integrity, freshness, nutritional value, appearance and taste. These characteristics concern the producer as well. Additional characteristics that concern the producer are growth rate, food conversion efficiency, population homogeneity, disease resistance, stress resistance, morpho-anatomical abnormalities and muscle cellularity. Quality characteristics are affected by procedures before and after the harvesting period, the fattening period and the period during the growth at the hatcheries. The target of the producer is to minimize the factors that alter the final quality of the product aiming the increase of the commercial value of the product.
For the description of quality, indices have been developed and can be characterized as either descriptors or predictors of the fish quality. The most known quality indices that are currently used in fish culture include, muscle fat and protein composition, morpho-anatomical abnormalities, external appearance of fish and the quality indices for growth rate. In the latter, individual growth rate, population heterogeneity, muscle cellularity and the estimation of age and growth rate of individuals with the use of calcified structures are included.
The main purpose of this research was the study of growth and differentiation of the hard structures of the zebrafish caudal fin and the probable utilization of the caudal fin as a new descriptor or/and predictor quality index. Fish caudal fin is composed of segmented rays which are known as lepidotrichia. Stretching out beyond the distal end of each lepidotrichium to the margin of the fin, are clusters of small thin spicules called actinotrichia. Growth of each lepidotrichium occurs via the addition of new segments at the distal end of each lepidotrichium. Segments are connected with intersegmental joints and once a segment is established do not grow further in length.
The shape of the zebrafish caudal fin is achieved through the allometric growth during the juvenile stage and the isometric growth during the adult stage. Isometric growth is achieved through mechanisms that control segment number and length.
In the present work two experiments were designed for the study of growth and differentiation of the hard structures of larvae, juvenile and adult zebrafish caudal fin.
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Πλαστικότητα της αύξησης και της διαφοροποίησης των σκληρών δομών του Zebrafish, Danio Rerio (Hamilton,1822)
