Question

Termination of gastrulation is indicated by
A. Obliteration of blastocoel
B. Obliteration of the archenteron
C. Closure of the blastopore
D. Closure of neural tube

Answer 1

During embryonic development, gastrulation is the process that transforms the embryo from a blastula with a single cell layer to a gastrula containing several cell layers. Gastrulation usually involves folding or separating the blastula into itself, which produces two cell layers.

Complete answer:
Human embryonic growth, or human embryogenesis, refers to the human embryo's development and creation. It is characterized by the cell division and cellular differentiation processes of the embryo that take place during the early stages of development.
We should first understand the phases of embryonic development in order to understand gastrulation.
Embryonic growth phases
Germinal process
Fertilization
Cleavage
The Blastulation
Implantation
Embryonic Disc
The gastrulation
Neurulation,
Production of organ systems and organs
Germinal stage:
Fertilization: After the spermatozoon has reached the ovum successfully, fertilization takes place, and the two sets of genetic material fuse together, resulting in a single diploid cell, the zygote.
Cleavage: As the zygote divides into two cells by mitosis, the beginning of the cleavage process is marked. This mitosis begins, and four cells are separated by the first two cells, then eight cells, and so on. The dividing cells, or blastomeres, were initially identified.
Blastulation: The first step of blastulation, the process of forming the blastocyst, is cleavage itself. Cells divide into an outer layer of cells and an inner cell mass (collectively called the trophoblast). In order to become embryo blasts, the inner mass of cells differentiates and polarises at one end. This polarisation leaves a void, the blastocoel, forming a structure now called the blastocyst.
Implantation: The blastomeres are arranged into an outer layer called the trophoblast in the blastocyst. Then the trophoblast differentiates itself into an inner layer, the cytotrophoblast, and the syncytiotrophoblast, the outer layer. Via projections of chorionic villi, the syncytiotrophoblast inserts the blastocyst in the deciduous epithelium, forming the embryonic portion of the placenta.
Embryoblast: An embryonic disc, a two-layer bilaminar disc, an upper layer called the epiblast (primitive ectoderm), and a lower layer called the hypoblast is formed by the embryoblast (primitive endoderm).
Gastrulation: The development of the primitive streak on the surface of the epiblast starts with gastrulation. A slightly elevated area surrounding the small primitive pit consists of the primitive node, the cephalic end of the streak.
Cells of the Epiblast move to the primitive strip. They become flask-shaped upon arrival in the area of the streak, detach from the epiblast, and fall below it. Others displace the hypoblast, creating the embryonic endoderm when the cells have invaded, and others come to lie between the epiblast and the newly developed endoderm to form the mesoderm. Cells that remain in the epiblast form ectoderm afterward. This internal movement is referred to as invagination. Hence, the process of gastrulation ends with blastocoel cavity obliteration and three layers of germ formation.
Neurulation: The ectoderm gives rise to epithelial and neural tissue after the gastrulation process and the gastrula is now referred to as the neurula.
Production of organ systems and organs: In Organogenesis there is the development of the organs during the third to eighth week, which begins and lasts until birth.

So, the correct option is option A - Obliteration of blastocoel.

Note: The cause of major congenital malformations may be toxic exposures in the embryonic phase, as the precursors of the major organ systems are now developing. First arch syndromes are congenital facial deformity conditions caused by the inability of neural crest cells to migrate to the first pharyngeal arch. The result of the incomplete closure of the neural tube is spina bifida congenital disorder.