Trophoblast give rise to :
Ans. is a, b and c i.e. Placenta; Chorion; and Amnion Friends, it is very easy to mug up that trophoblast forms the placenta and fetal membranes viz chorion and amnion. But if you really want to understand and know what is trophoblast and how it forms the placenta and fetal membranes, you will have to revise embryology with me : As feilisation of the ovum occurs and a zygote is formed. it undergoes cleavage to form 3. 4. 6 cell stage. This cleavage continues till it is 16 cell staged and is called as Morula. Cells of morula differentiates into an inner cell mass which is completely surrounded by an outer layer of cells. The cells of the outer layer give rise to a structure called as the trophoblast The trophoblast has the propey of being able to stick to uterine (or other) epithelium and invade and burrow the tissues with which they come in contact. Therefore to prevent this 'sticking' - trophoblast is surrounded by zona pellucida. Some fluid passes from the uterine cavity into the morula. So that the inner cell mass attaches to trophoblast on one side only. The morula now becomes a blastocysf. As the blastocyst develops fuher the inner cell mass differentiates into ectoderm and endoderm initially followed by mesoderm later. The trophoblast gives origin to amnion, chorion and the placenta. Extra Edge Development of the embryo from feilisation up to the formation of bilaminar disc is described as the 'pre - organogenesis period These events take place in the first 14 days of pregnancy. Anomalies produced by teratogens acting during this period usually result in death of the embryo. These anomalies are therefore seldom seen in babies reaching full term. Establishment of the primitive streak and formation of intra embryonic mesoderm mark the onset of "gastrulation"or the "embryonic period" (from the 3r0 week to flth week). Most congenital anomalies are produced by teratogens acting during this period. Time table of events Age in days Developmental Events 2 Embryo is at two - cell stage 3 Morula is formeddeg 4 Blastocyst is formed 8 Bilaminar disc is formeddeg 14 Prochordal plate and primitive streak is seen 16 Intra-embryonic mesoderm is formed / disc is now three layereddeg
Placenta
Chorion
Amnion
All of these