EVERYDAY SCIENCE

Detailed explanation-1: -The ectoderm gives rise to the skin and the nervous system. The mesoderm specifies the development of several cell types such as bone, muscle, and connective tissue. Cells in the endoderm layer become the linings of the digestive and respiratory system, and form organs such as the liver and pancreas.

Detailed explanation-2: -The endoderm is the innermost germ layer that forms the linings of the respiratory and gastrointestinal tracts, and their associated organs, during embryonic development.

Detailed explanation-3: -Gastrulation is characterized by cell movement and reorganization within the embryo (morphogenetic movements) to the interior of the embryo, forming three primary germ layers: ectoderm, mesoderm, and endoderm. the mesoderm lies between these two layers.

Detailed explanation-4: -During gastrulation, a hollow cluster of cells called a blastula reorganizes into two primary germ layers: an inner layer, called endoderm, and an outer layer, called ectoderm.

Detailed explanation-5: -The endoderm constructs the digestive tube and the respiratory tube. 15. Four pairs of pharyngeal pouches become the endodermal lining of the eustacian tube, tonsils, thymus, and parathyroid glands. The thyroid also forms in this region of endoderm.