Embryology

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Embryology is the study of the development of an embryo. Embryology literally means the study of embryos, but this definition is restrictive. An embryo is an immature organism contained within the coverings of an egg or within the body of the mother. Strictly speaking, the embryonic period ends at metamorphosis, hatching, or birth. Since developmental processes continue beyond these events, the scope of embryology is customarily broadened to encompass the entire life history of an organism. Embryology may, in this wider context, consider the mechanisms of both asexual reproduction and regeneration.

After the 1950s, with the DNA helical structure being discovered by James D. Watson and

Francis Crick, (in collaboration with Rosalind Franklin and Maurice Wilkins) and the increasing knowledge in the field of molecular biology, developmental biology emerged as the field of study that correlates the genes and such morphological changes; in other words, which genes are responsible for each morphological change that takes place in an embryo, and how these genes are regulated.

Many principles of embryology apply to both invertebrate animals as well as to vertebrates.^[1] Therefore, study of invertebrate embryology has advanced the study of vertebrate embryology. However, there are many differences as well. For example, numerous invertebrate species release a larva before development is complete; at the end of the larval period, an animal for the first time looks like an offspring of its parents. Although invertebrate embryology is similar in some ways for different invertebrate animals, there are also countless variations. For instance, some insects proceed directly from egg to adult form whereas others develop through an elaborate sequence of changes.

[edit] Neuroembryology

Neuroembryology refers to the development of an embryos nervous system. At the middle of the third week the neural plate appears which originates from the ectoderm.

[edit] See also

• Ontogeny
• Embryogenesis
• Recapitulation theory
• Prenatal development

[edit] Footnotes

1. ^ Parker, Sybil. "Invertebrate Embryology," McGraw-Hill Encyclopedia of Science & Technology (McGraw-Hill 1997).

[edit] References

• UNSW Embryology Large resource of information and media

[edit] Further reading

• Scott F. Gilbert. Developmental Biology. Sinauer, 2003. ISBN 0-87893-258-5.
• Lewis Wolpert. Principles of Development. Oxford University Press, 2006. ISBN 0-19-927536-X.

[edit] External Links

• Embryo Research UK philosophy and ethics website discussing the ethics of embryology
• Human embryo research Canadian website covering the ethics of human embryo research