<prompt> Internal organs in the fetus develop at24 weeks12 weeks10 weeks6 weeks  <response>: D i.e. 6 weeks The embryonic period or period of organogenesis occurs from 3rd- weeksQ Langmans 4th- 801 weeksQ Persuad Although the critical development events occur during first three weeks, such as cleavage of the zygote, blastogenesis early development of the nervous cardiovascular systems. All major external internal structures are established during 4- 8 weeks. 