- knolik
yolk-sag
Значение термина yolk-sag в knolik
yolk-sag - yolk-sag
yolk-sag - Sac containing yolk which hangs from ventral surface of very yolky vertebrate embryos (elasmobranchs, teleosts, reptiles, birds). Has outer layer of ectoderm; inner layer, usually absorptive, of endoderm; with mesoderm containing coelom and blood-vessels between. The endoderm is in effect a diverticulum of the gut, the yolk- or fluid-filled space within it communicating with intestine of embryo (not in teleosts). In mammals the yolk-sac, quite empty of yolk, is only the endodermal sac, with its layer of mesoderm, homologous with that of the other vertebrates; the ectodermal layer with its mesoderm is called part of the chorion. The same terminology is often applied to the other amniotes. As absorption of yolk proceeds, yolk-sac is withdrawn until it merges into the embryo; but most of it is cut off from the embryo at birth in mammal.
Рядом со словом yolk-sag в knolik
| yolk | В начало буква "" буквосочетание "" | zeatin |
Статья про yolk-sag была прочитана 287 раз
- - TOP 200
- - mycophyta
- - alloys furnaces
- - binomial nomenclature
- - alloys, bronze
- - ainley, henry hinchliffe
- - august 21
- - ranunculus trichophyllus chaix
- - ranunculus fluitans lamarck
- - ranunculus hederaceus l.
- - ranunculus heterophyllus weber
Our friends, knolik encyclopaedia knolik.com