| A | B |
|---|
| aggregation | clustering of cells |
| animal pole | end of egg with lowest yolk-concentration |
| archenteron | gastrocoel or primitive gut |
| blastocoel | cavity formed in embryo during blastulation |
| blastocyst | inner cell mass surrounded by trophoblast |
| blastomere | cell of a blastula |
| blastopore | site of involution of cell sheet during gastrulation |
| blastula | zygote - hollow sphere of cells |
| chordomesoderm | tissue that gives rise to notochord |
| cleavage | separation of cells during cell division |
| coelom | cavity between splanchnic and somatic mesoderm |
| coelomic pouch | pocket of tissue arising from anteriormost end of mesoderm |
| conceptus | embryo plus extraembryonic membrane |
| delamination | separation of a cell sheet into two cell sheets |
| dorsal mesoderm | longitudinal band of mesoderm paralleling the notochord |
| ectoderm | germ layer giving rise to skin and nerve cord |
| epiboly | spreading of a cell sheet |
| embryonic disk | remnant of mammalian inner cell mass after hypoblast delamination |
| endoderm | germ layer giving rise to gut |
| euviviparous | when animals give birth to offspring that have been nourished by mother's tissue |
| evagination | outpocketing of cells |
| gastrula | trilaminar embryo |
| Hensen's node | thickened patch of blastoderm cells that determine caudal end of embryo |
| ingression | sinking of cells from a surface into an area |
| inner cell mass | embryo forming cells in mammalian blastocyst |
| intermediate mesoderm | forms kidney tubules and ducts of urogenital system |
| invagination | inpocketing of cell sheet |
| involution | movement of an outer layer of cells around a corner and spreading across an inner surface |
| isolecithal | yolk evenly distributed in egg |
| lateral mesoderm | gives rise to somatic and splanchnic mesoderm |
| macrolecithal | egg with a high yolk content |
| microlecithal | egg with a low yolk content |
| mesolecithal | egg with a medium yolk content |
| mesenchyme | multipotent cells that move by amoeboid motion |
| mesodermal somites | structure formed when dorsal mesoderm segregates into brick-shaped packets |
| migration | movement of cells |
| morphogenetic | body plan determining |
| morphogens | pattern-forming chemicals |
| morula | early embryo - solid ball of cells |
| neurula | embryonic stage where neuroectoderm separates from cutaneous ectoderm |
| neurulation | formation of nerve cord |
| neural groove | cleft formed as neural folds pitch upward |
| neural keel | wedge-shaped band of ectoderm that invades dorsal body wall in fish |
| neural plate | thickened layer of ectoderm overlying notochord |
| neurocoel | central cavity of central nervous system |
| neuropore | opening at the end of the nerve tube |
| notochord | mesoderm-derived structure, induces neuroectoderm |
| ovoviviparous | young born from mother - only get oxygen from maternal tissues |
| primitive streak | blastopore in birds |
| somatic mesoderm | outer sheet formed from lateral plate mesoderm |
| splanchnic mesoderm | inner sheet formed from lateral plate mesoderm |
| splanchnopleure | splanchnic mesoderm plus endoderm |
| somatopleure | somatic mesoderm plus ectoderm |
| telolecithal | yolk greatly concentrated at one end of the egg |
| trophoblast | nutritional membrane produced from vegetal pole cells in mammalian blastula |
| vegetal pole | end of egg with greatest concentration of yolk |
| viviparous | animals giving birth to offspring |
| oviparous | egg-laying animals |
