Research On The Ontogenesis Of Haemocytes In Larval Development Of Scallop Chlamys Farreri

In this paper, embryos and larvaes from different developmental stages of scallop Chlamys farreri including blastula, gastrula, trochophore, D larvae, post-D larva, umbo larvae and juvenile were collected successively from a scallop farming area in Weihai, Shandong province. The collected samples were fixed, embedded by paraffin and sliced, and the resulting slices were examined by hematoxylin and eosin (H&E) staining. In the meantime, these slices were used to study the ontogenesis of haemocytes in different developmental stages of C. farreri by immunohistochemistry (IHC) assay, which was employed a monoclonal antibody (MAb) specific for haemocytes of C. farreri as a tracer. The results showed positive signals were firstly detected at D larval stage which was about 2 days after insemination, and localized in mantle, velum base, esophagus, digestive gland, foot, etc. However, the distinguishable positive haemocytes (ellipse, diameter of 3-5μm) were observed in umbo larval stage which was about 5 days later than D larva, and localized in mantle, velum base, digestive gland and around esophagus. Moreover, about one week later, in juvenile stage, all developed tissues and organs are very similar to those of adult scallop except gonad, the positive rate of IHC were increased rapidly, haemocytes with positive signals distributed all over the visceral mass including gill, matle, digestive gland, esophagus. Conclusively, haemocytes appeared at the early stage of D larva, and they were distributed in tissues and organs which are associated with digestion like gill, digestive gland etc.