Table of Contents
Gastrulation is the process by which the cells of a blastula are rearranged into the three germ layers of an embryo. The ectoderm, mesoderm, and endoderm are the primary germ layers of an embryo.
Embryonic Development and Cleavage
The embryonic development process begins with fertilization, when the male sperm and female egg merge to create a single cell. This new cell begins to divide, and over the next few days will grow into a tiny embryo. The embryo will then grow into a fetus, and eventually a baby.
Cleavage is the process of cell division that occurs in the embryo. The cells will divide again and again, and will eventually form into a ball of cells called a blastocyst. The blastocyst will then implant into the uterine wall, and begin to grow into a fetus.
Morula and Blastula
The morula is a small, round, solid mass of cells that forms from the fertilized egg. The blastula is a hollow ball of cells that forms from the morula. The blastula develops a cavity or lumen filled with fluid. The cells that form the blastula are called blastomeres.
Gastrula Stage and Gastrulation
The gastrula stage is the stage of embryonic development in animals after the blastula stage. This stage is marked by the development of a gastrula, a structure that has a double-layered body wall and a central cavity. The gastrula is formed when the cells of the blastula differentiate into three germ layers: the ectoderm, the endoderm, and the mesoderm. The ectoderm gives rise to the skin and the nervous system, the endoderm gives rise to the gut and the respiratory system, and the mesoderm gives rise to the muscles, skeleton, and circulatory system.
Formation of Primary Germ Layer
The process of forming the primary germ layer begins with the formation of a small, hollow ball of cells called a blastocyst. The blastocyst contains a cluster of cells called the inner cell mass (ICM) and a layer of cells surrounding the ICM called the trophectoderm.
The trophectoderm gives rise to the placenta and the embryo’s other extra-embryonic membranes. The ICM gives rise to the embryo’s three primary germ layers: the endoderm, the mesoderm, and the ectoderm.