Morula
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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 blastocystic cavity appears and the morula becomes a "blastocyst."
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| Mammalian development of embryo and development of fetus (some dates are approximate - see Carnegie stages) |
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| Week 1: Zygote - Morula - Blastula/Blastomere/Blastosphere - Archenteron/Primitive streak - Blastopore - Allantois - Trophoblast (Cytotrophoblast - Syncytiotrophoblast - Gestational sac)
Week 2: Yolk sac - Vitelline duct - Bilaminar disc Week 3: Hensen's node - Gastrula/Gastrulation - Trilaminar embryo Branchial arch (1st) - Branchial pouch - Meckel's cartilage - Somite/Somitomere - Sclerotome - Myotome - Germ layer (Ectoderm, Endoderm, Mesoderm, Chordamesoderm, Paraxial mesoderm, Intermediate mesoderm, Lateral plate mesoderm, Splanchnopleure, Somatopleure) Histogenesis and Organogenesis Uterine support: Placenta - Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) - Amniotic sac (Amnion, Chorion) |
