[Music] pregnancy is gauged utilizing gestational age gestational age begins on the initial day of one'' s last menstrual duration because it is tough to inform the exact day of fertilization at one or 2 weeks expectant a person has not yet conceived ovulation occurs beginning in week 3 of pregnancy if a sperm fertilizes the egg after that maternity takes place at three weeks of pregnancy the sperm and egg have participated in the fallopian tubes the fertilized egg is currently recognized as a zygote as the cells within the zygote start splitting it comes to be a mass referred to as ammorla about 4 days after fertilizing the morula goes into the uterus and turns into a blastocyst the inner cells of the blastocyst will become the baby and the outer layer will establish into the yolk cavity and placenta by the end of the week the blastocyst will certainly begin to dental implant into the uterine lining this procedure called implantation is effective 25 to half of the moment at four weeks of pregnancy the blastocyst has actually installed in the uterine lining the blastocyst cells form layers that are becoming the embryo yolk cavity and the future amniotic sac and placenta the yolk cavity will momentarily nourish the embryo till the placenta develops in spite of the yolk sac'' s name human yolk sacks consist of brand-new yolk [Songs]
