1. 1.Fertilization: Fusion between egg and sperm. 2.Cleavage: Rapid cell multiplication of zygote. 3.Blastulation: Ball of cells lined by blastoderm and enclosed with blastocoele cavity. 4.Gastrulation: Rapid cell movement of blastula cells leading to formation of germ layers; ectoderm, mesoderm & endoderm. 5.Neurulation & Formation of organ rudiment: Formation of primitive organ rudiments. 6.Organogenesis: Formation of organs Basic Concepts of animal development:

2. Embryonic Development

4. Kinds of Embryo Axis Superior or cranial and inferior or caudal : Used to determine the relationships to the head and tail respectively. Frontal or coronal section: Any vertical plane that intersects the median plane at right angles and divides the body into front (anterior or ventral ) and back (posterior or dorsal). Sagital or mid-sagital section: Any vertical plane passing through the body that is parallel to the median plan. Median plane : This is imaginary vertical plane of the section that passes longitudinally through the body. Lateral and medial plane : Refer to the structures that are respectively farther from or nearer to the median plane of the body. Transverse or horizontal section: Any plane that is at right angles to both the median or coronal planes.