engleski

Development of mammalian postimplantation embryos in different experimental systems

Different experimental systems are used to study developmental processes in mammals:1)cultivation in vitro ; 2)transplantation in vivo ; 3)combination of culture in vitro and transplantation in vivo. In this study those experimental systems were analysed and correlated. The mid-gastrula stage rat and mouse embryos were cultivated in vitro for 14 days. After in vitro culture embryos were cultivated in vitro for 14 days. After in vitro culture embryos were either taken for histology or grafted under the kidney capsule for additional 14 days. Only rat embryos were grafted in vivo after culture in vitro, or directly as a control. After 14 days in vitro different germ layers derivatives: epithelia, neuroblasts, cartilage and myotubes developed in mouse and rat embryos. In grafts pre-cultivated for 14 days most tissues developed further. Bone and adipose tissue appeared after transplantation. Altough anatomical relationship were lost, smotimes tissues were organized in organotypisc combinations: brain-like tissue and choroid plexus, gut epithelium with smooth muscles and ganglionic cells, respiratory epithelium with cartilage, epidermis with derivatives resembling the skin and glandular epithelia (mucous, serous). Rarely, thyroid follicles and bell stage of the tooth development were found. Morphologically, differentiated tissues wre similar to those found in directly transplanted embryos, but in pre-cultivated grafts their incidence were lower. It can be concluded that the inital restriction of developmental potential in vitro was partially reversible in metabolically rich enviroments invivo, and depends on media used for cultivation, i.e. added substances. Manipulation with in vitor conditions affects developmental potential. Thus, combination of in vitro and in vivo methods integrates advantages of both techniques: controled in vitro conditions and metabolically rich enviroments in vivo.

rat; embryo; development

nije evidentirano