AskDefine | Define blastula

Dictionary Definition

blastula n : early stage of an embryo produced by cleavage of an ovum; a liquid-filled sphere whose wall is composed of a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus occurs [syn: blastodermic vesicle] [also: blastulae (pl)]

User Contributed Dictionary



  1. An early form in the development of an embryo, consisting of a spherical layer of cells filled with fluid; a blastosphere

Related terms

Extensive Definition

The blastula 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 surrounding a central fluid-filled cavity called the blastocoel. The blastula follows the morula and precedes the gastrula in the developmental sequence.


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

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.


blastula in German: Blastula
blastula in Spanish: Blástula
blastula in French: Blastula
blastula in Italian: Blastula
blastula in Lithuanian: Blastulė
blastula in Polish: Blastula
blastula in Portuguese: Blástula
blastula in Slovak: Blastula
blastula in Serbian: Бластула
blastula in Turkish: Blastula
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