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In developmental biology, the Hamburger–Hamilton stages (HH) are a series of 46 chronological stages in chick development, starting from laying of the egg and ending with a newly hatched chick. It is named for its creators, Viktor Hamburger and Howard L. Hamilton. Chicken embryos are a useful model organism in experimental embryology for a ...
Hans Spemann. Viktor Hamburger (July 9, 1900 – June 12, 2001) [ 1][ 2] was a German-American professor and embryologist. His collaboration with neuroscientist Rita Levi-Montalcini resulted in the discovery of nerve growth factor. [ 3] In 1951 he and Howard Hamilton published a standardized stage series to describe chicken embryo development ...
In the chick embryo, somites are formed every 90 minutes. In the mouse the interval is 2 hours. [7] For some species, the number of somites may be used to determine the stage of embryonic development more reliably than the number of hours post-fertilization because rate of development can be affected by temperature or other environmental factors.
Anatomical terminology. [ edit on Wikidata] Gastrulation is the stage in the early embryonic development of most animals, during which the blastula (a single-layered hollow sphere of cells ), or in mammals the blastocyst, is reorganized into a two-layered or three-layered embryo known as the gastrula. [ 1]
In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell, ( spermatozoon ). [ 1] Once fertilized, the ovum becomes a single diploid cell known as a zygote.
Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possibly by brooding and hatching the egg. Multiple and various factors are vital to the incubation of various ...
The development of the pharyngeal arches provides a useful landmark with which to establish the precise stage of embryonic development. Their formation and development corresponds to Carnegie stages 10 to 16 in mammals , and Hamburger–Hamilton stages 14 to 28 in the chicken .
Carnegie stages. In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo . The stages are delineated through the development of structures, not by size or the number of days of development, and so the chronology can vary between species, and to a certain ...