NEET BIOLOGY

Detailed explanation-1: -Gastrulation is an early stage of development during which an embryo, then a single-layered ball of cells called a blastula, reorganizes itself into a three-layered ball of cells, called a gastrula. During this process, the primary germ layers, endoderm and ectoderm, interact to form the third, called mesoderm.

Detailed explanation-2: -In all animals, except for organisms of the phylum Cnidaria, the endoderm and ectoderm interact to produce a third germ layer, called mesoderm.

Detailed explanation-3: -On day 20, mesoderm cells around the notochord differentiate into three specialized types of mesoderm called the paraxial mesoderm, intermediate mesoderm, and lateral plate mesoderm, each of which goes on to make different tissues and organs.

Detailed explanation-4: -Cells in each germ layer differentiate into tissues and embryonic organs. The ectoderm gives rise to the nervous system and the epidermis, among other tissues. The mesoderm gives rise to the muscle cells and connective tissue in the body. The endoderm gives rise to the gut and many internal organs.