Question

Gastrulation is a process of
A. Formation of archenteron
B. Migration of prospective endo mesodermal cells
C. Differentiation of three primary germ layers
D. All of the above

Answer 1

The organisms undergo reproduction by fusion of male and the female gametes. The gametes fusion results in the formation of embryos that later develop into fetus. But during this development the cell undergoes cell division and finally forms three germ layers that later form different tissues.

Complete Answer:
- The male gametes are termed as sperm and the female gametes are termed as ova or egg. In the sexual reproduction process both the male and female gametes fuse together for fertilization.
- In humans, both egg and the sperm cells are produced separately depending on the gender but in some organisms. The zygote undergoes mitotic cell division and forms two cells that are termed as embryos. The continued division of embryonic cells to form blastula. Animals like frogs go further division of cells to form gastrula.
- Gastrula is a two layer sac with an opening at one end formed in embryonic development. In some animals the zygote undergoes mitotic cell division and forms two cells that are termed as embryos. The continued division of embryonic cells to form blastula. Animals like frogs go further division of cells to form gastrula. It seems like a double bubble that means one bubble inside another bubble.
- Now, the gastrulation initiated with the formation of the streak on the epiblast surface, the streak is vaguely after 15 to 16 day of embryo. It is clearly visible as a groove with a bulging part on each site. The cephalic end of the streak forms the primitive node. The epiblast cells move towards the primitive streak and form a flask shaped that gets detached from the epiblast and slips beneath the cell.
- Then the hypoblast gets displaced after the cell gets invaginated and forms embryonic endoderm and the next cell is present between the epiblast and newly formed endoderm to produce mesoderm. The cells found in the epiblast form the ectoderm. Thus, the epiblast is the source of all the germ layers and this gives rise to all the other tissue and organs in the embryo.
- These three germ layers are; the ectoderm, the endoderm, and the mesoderm. The primitive gut that forms during the gastrulation in the developing embryo is termed as archenteron or the digestive tube. It is further developed into the digestive tract of the organisms.

Thus, the correct option is ‘D’. All of the above.

Note: Some of the primitive organisms are diploblastic in nature that means they consist of two germ layers, ectoderm and endoderm. The organisms that have three germ layers are considered as triploblastic in nature.