You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Indicator of sta of gastrulation is the formation of ? and explain in detail?
Ans. is 'c' i.e., Primitive streak Gastrulation, the most characteristic even occurring during Yd week of gestation, establishes all 3 germ layers (ectoderm, mesoderm & endoderm). It conves the bilaminar embryonic disc into a trilaminar, and is the beginning of morphogenesis. Ectoderm is first and mesoderm is last to develop.1" sign of gastrulation is appearance of primitive streak on the surface of epiblast. The primitive streak appears caudally in the median plane on dorsal aspect of the embryonic disc. So now it's possible to identify the embryo's craniocaudal axis, its cranial and caudal end, its dorsal and ventral surfaces, and its right and left sides.