![]() During breeding season (rainy season), the croaking of male attracts the female frog.Ova are larger than sperms, non-motile and nearly spherical.The sperms are microscopic, thread like and motile, 0.03mm in length.Sperms and ova (eggs) are produced by respective gonads in males and females by meiosis.Sequential events in the development of frog: Growth: Increase in size and weight through cell division and cell enlargement.Morphogenesis: Growth and differentiation of form and structure.Organogenesis: Development and differentiation of different organs from primary germ layers.Gastrulation: Movement and rearrangement of cells.Blastulation: Formation of hollow ball of cells.Morulation: Formation of solid ball of cells.Cleavage: Repeated divisions taking place in the zygote.Fertilization: Fusion of male and female gametes to form a zygote.Mating: Transfer of male gametes inside female’s body by copulation.Gametogenesis: Formation of gametes or sex cells.Sequence of events before and during embryonic development in living organisms: You may also want to see: The process of fertilization and development of embryo in angiosperms The development of embryo takes place in an orderly sequence and follows the same fundamentally similar sequence of events in almost all sexually reproducing organisms.The branch of biology dealing with the study of embryo is known as embryology.Embryo is the earliest stage of development, while it is within the egg or reproductive organs of mother until hatching or birth.Zygote divides and re-divides to form an embryo.In sexual reproduction, development of organisms begins with a fertilized egg or zygote.
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