AskDefine | Define morula

Dictionary Definition

morula n : a solid mass of blastomeres that forms when the zygote splits; develops into the blastula [also: morulae (pl)]

User Contributed Dictionary



  1. A spherical mass of blastomeres that forms following the splitting of a zygote; it becomes the blastula

Extensive Definition

A morula (Latin "morus", mulberry) is an embryo at an early stage of embryonic development, consisting of approximately 12-32 cells (called blastomeres) in a solid ball contained within the zona pellucida.


The morula is produced by embryonic cleavage, the rapid division of the zygote. After reaching the 16-cell stage, the cells of the morula differentiate. The inner blastomeres will become the inner cell mass and the blastomeres on the surface will later flatten to form the trophoblast. As this process begins, the blastomeres change their shape and tightly align themselves against each other to form a compact ball of cells. This is called compaction and is likely mediated by cell surface adhesion glycoproteins.


In mammals the morula travels to the uterus around 3-4 days after fertilization, and at about 4 days after fertilization a fluid-filled space called the blastocoel cavity appears and the morula becomes a blastocyst.

Additional images

Image:Embryo, 8 cells.jpg|Morula, 8 cell stage
morula in Bulgarian: Морула
morula in Czech: Morula
morula in German: Morula
morula in Spanish: Mórula
morula in French: Morula
morula in Italian: Morula
morula in Lithuanian: Morulė
morula in Occitan (post 1500): Morula
morula in Polish: Morula
morula in Portuguese: Mórula
morula in Slovak: Morula
morula in Swedish: Morula
morula in Turkish: Morula
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