<prompt> Monochorionic monoamniotic twin occurs if division occurs:Before 24 hours1-4 days4-8 days8 days  <response>: If the division occur after eight day of feilisation,when the amniotic cavity has already formed,a monoamniotic-monochorionic twin develops. Reference:DC Dutta;s textbook of obstetrics,8th edition, page no:233. p 