Blastula
Blastulation. 1 - morula, 2 - blastula.
Days	4

The blastula (from Greek βλαστός (blastos), meaning "sprout") is an early stage of embryonic development in animals. It is also called blastosphere. It is produced by cleavage of a fertilized ovum and consists of a spherical layer of around 128 cells with a large fluid filled space called the blastocoel in the animal pole of the embryo. The blastula follows the morula and precedes the gastrula in the developmental sequence.

[edit] Research

A whitefish blastula is often used to help study the processes of mitosis in animal cells.^[1] The blastula is prevented from multiplying during the nuclear-injection stage.

[edit] Blastula and blastocyst

In mammals, blastulation leads to the formation of the blastocyst, which must not be confused with the blastula; even though they are similar in structure, their cells have different fates. The blastocyst contains an embryoblast as well.

[edit] References

1. ^ "Whitefish Mitosis". http://biology.northwestcollege.edu/biology/b1010lab/mitwfish.htm. Retrieved 2007-10-11. 

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v • d • e Developmental biology > Human embryogenesis (development of embryo) and development of fetus First three weeks Week 1 Fertilization · Egg activation · Zygote · Cleavage · Morula · Blastula (Blastomere) · Blastocyst · Inner cell mass Week 2 (Bilaminar) Hypoblast · Epiblast Week 3 (Trilaminar) Germ layers Archenteron/Primitive streak (Primitive pit, Primitive knot/Blastopore, Primitive groove) · Gastrula/Gastrulation · Regional specification Ectoderm Surface ectoderm · Neuroectoderm · Somatopleure · Neurulation · Neural crest Endoderm Splanchnopleure Mesoderm Chorda- · Paraxial (Somite/Somitomere/Sclerotome/Myotome/Dermatome) · Intermediate · Lateral plate (Intraembryonic coelom, Splanchnopleure/Somatopleure) Extraembryonic/ uterus Trophoblast (Cytotrophoblast, Syncytiotrophoblast) Blastocoele · Yolk sack/exocoelomic cavity · Heuser's membrane · Extraembryonic coelom · Vitelline duct Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) · Allantois Placenta · Decidua (Decidual cells) · Chorionic villi/Intervillous space · Gestational sac (Amnion/Amniotic sac/Amniotic cavity, Chorion) Histogenesis Programmed cell death (Apoptosis) · Stem cells · Germ line development Organogenesis Limb development: Limb bud · Apical ectodermal ridge/AER other structures: Eye development · Cutaneous structure development · Heart development · Development of the urinary and reproductive organs (Some dates are approximate—see Carnegie stages and a timeline.)