Limitation:

• Difficulty in in vitro culturing and maintenance of pluripotent ES cells.
• Germ line transfection with low frequency.

Fig 6-3.3.3: Embryonic stem cell technology

6-3.3.4 DNA Microinjection:

DNA microinjection technique was first described in 1966 by T. P. Lin, which paved the way of generating transgenic animal by direct introduction of foreign DNA into the host cell. Linearized DNA construct is injected into the cell which finally integrates to the host genome at random sites by homologous recombination. DNA microinjection can be targeted to two sites: Pronuclear injection and cytoplasmic injection. Following steps are involved in production of transgenic animal by microinjection: