"An embryo is an initial stage of development of a multicellular organism."
Series of synchronous and closely timed events that form an embryo from a fertilized egg.
Fertilization: The process of the fusion of gametes to initiate embryonic development.
Cleavage and blastula formation: The rapid cell division of the fertilized egg that leads to the formation of a hollow ball of cells, the blastula.
Gastrulation: The process by which the embryo transforms from a bilaminar disc to a trilaminar disc, with the formation of the three germ layers - ectoderm, mesoderm, and endoderm.
Neurulation: The process of formation of the nervous system from the ectoderm, including the neural tube and neural crest cells.
Organogenesis: The formation of specific organs and tissues in the developing embryo, such as the heart, lungs, liver, and kidneys.
Limb development: The process of formation of the upper and lower limbs in the embryo, including the development of bones, muscles, and blood vessels.
Cell differentiation and specialization: The process by which cells become specialized to perform specific functions within the developing embryo.
Cell signaling and communication: The mechanisms by which cells interact and communicate with each other during embryonic development.
Epigenetics and gene regulation: The study of changes in gene expression that occur during embryonic development, which are influenced by environmental and genetic factors.
Stem cells and regeneration: The role of stem cells in embryonic development and their potential for tissue regeneration and repair.
Developmental abnormalities and defects: The study of developmental disorders and their underlying causes, such as genetic mutations or environmental factors.
Evolution and comparative embryology: The study of the evolution of embryonic development and the role of comparative embryology in understanding the relationships between different species.
Oviparous: In this type of embryogenesis, the fertilized eggs are laid outside of the body of the female and development occurs outside of the maternal body. Examples include birds, reptiles and fish.
Viviparous: In this type of embryogenesis, development of the embryo occurs inside the body of the female and the offspring is born live. Examples include mammals such as humans, dogs and cats.
Ovoviviparous: In this type of embryogenesis, the eggs are retained and develop inside the female’s body, but are not dependent on maternal nutrition. The offspring are then born live. Examples include some species of fish and snakes.
Hemimetabolism: In this type of embryogenesis, the organism undergoes incomplete metamorphosis. The young are born with fully formed wings but lack sexual maturity. Examples include grasshoppers and dragonflies.
Holometabolism: In this type of embryogenesis, the organism undergoes complete metamorphosis. The young are born in a larval form and then undergo a series of development stages before reaching the adult stage. Examples include butterflies, moths, beetles and flies.
Polyembryony: In this type of embryogenesis, multiple embryos develop from a single fertilized egg. Examples include certain species of bees and wasps.
Parthenogenesis: In this type of embryogenesis, embryos are formed without fertilization by a sperm. Examples include some species of lizards, snakes, fish and birds.
Indirect development: In this type of embryogenesis, the young are born as a larva and undergo a series of developmental stages before reaching adulthood. Examples include most marine invertebrates.
Direct development: In this type of embryogenesis, the offspring are born as miniature adult forms and do not undergo any developmental stages. Examples include some species of amphibians, reptiles and mammals.
"Embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell."
"The resulting fusion of these two cells produces a single-celled zygote."
"The blastomeres are arranged as a solid ball that when reaching a certain size, called a morula, takes in fluid to create a cavity called a blastocoel."
"The structure is then termed a blastula, or a blastocyst in mammals."
"The mammalian blastocyst hatches before implanting into the endometrial lining of the womb."
"Once implanted, the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis."
"Gastrulation is the formation of the three germ layers that will form all of the different parts of the body."
"Neurulation forms the nervous system."
"Organogenesis is the development of all the various tissues and organs of the body."
"A newly developing human is typically referred to as an embryo until the ninth week after conception when it is then referred to as a fetus."
"In other multicellular organisms, the word 'embryo' can be used more broadly to any early developmental or life cycle stage prior to birth or hatching."
"Embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell."
"The structure is then termed a blastula, or a blastocyst in mammals."
"The mammalian blastocyst hatches before implanting into the endometrial lining of the womb."
"The embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis."
"Gastrulation is the formation of the three germ layers that will form all of the different parts of the body."
"Neurulation forms the nervous system."
"Organogenesis is the development of all the various tissues and organs of the body."
"A newly developing human is typically referred to as an embryo until the ninth week after conception when it is then referred to as a fetus."