Placenta.
Placenta.
The first system to form in a human embryo is the nervous system. The neural tube, which will develop into the brain and spinal cord, is one of the earliest structures to develop in the developing embryo.
trophoblast cells i.e the outer cells of blastocyst(1st embryonic stage in man) gives rise to amnion chorion allantois and yolk sac the 4 protective layer of embryo and inner cells called embryoblast gives rise to embryo
During the period of the embryo, which lasts from fertilization to around eight weeks of development, the cells divide and specialize to form the basic structures of the body. Major organs and systems start to form and the embryo becomes more recognizable as a human being. This period is critical for proper development as any disruptions during this time can have lasting effects on the individual.
An embryo is the early stage of development of a multicellular organism. In humans, the embryo is formed during the first eight weeks of gestation following fertilization of an egg by sperm. The embryo undergoes rapid cell division and differentiation to form the basic structures of the body.
The amniotic sac and placenta begin to form shortly after conception. The amniotic sac develops from the outer membranes surrounding the embryo, starting around the second week of pregnancy, while the placenta begins to form from the trophoblast cells that surround the developing embryo around the same time. By the end of the first trimester, both structures are well-established, providing essential support and protection for the growing fetus.
The inner cell mass of the blastocyst develops into the body of the embryo. This inner cell mass will give rise to the different cell types and structures that form the developing fetus.
The amniotic sac forms during the embryonic stage of development, around week 2 after fertilization. It is a protective membrane filled with amniotic fluid that surrounds and cushions the developing embryo/fetus in the uterus.
When the cell mass is fully implanted in the uterus, it is called a blastocyst. This is an early stage of development in mammalian embryos, just before the embryo begins to form distinct structures.
That is called an embryo, which is the earliest stage in the development of an organism. It is the stage where the organism's basic body structures start to form.
An embryo typically develops into a fetus around 8 weeks after fertilization. At this point, the major organs have begun to form and the fetus starts to resemble a human.
The bones of the skull that form a protective covering of the brain are the frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones. They encase and protect the delicate structures of the brain from external trauma.