Morula

From Wikipedia, the free encyclopedia
Jump to: navigation, search
For the South African football player, see Lebohang Morula.
Morula
Blastulation.png
Blastulation. 1 - morula, 2 - blastula.
Gray9.png
First stages of segmentation of a fertilized mammalian ovum. Semidiagrammatic. z.p. Zona pellucida. p.gl. Polar bodies. a. Two-cell stage. b. Four-cell stage. c. Eight-cell stage. d, e. Morula stage.
Details
Days 3
Zygote
Gives rise to Blastula, Blastocyst
Identifiers
Gray's p.46
Code TE E2.0.1.2.0.0.11
Anatomical terminology

A morula (Latin, morum: mulberry) is an embryo at an early stage of embryonic development, consisting of cells (called blastomeres) in a solid ball contained within the zona pellucida.[1]

The morula is produced by a series of cleavage divisions of the early embryo, starting with the single-celled zygote. Once the embryo has divided into 16 cells, it begins to resemble a mulberry, hence the name morula (Latin, morus: mulberry).[2] Within a few days after fertilization, cells on the outer part of the morula become bound tightly together with the formation of desmosomes and gap junctions, becoming nearly indistinguishable. This process is known as compaction.[3][4] A cavity forms inside the morula, by the active transport of sodium ions from trophoblast cells and osmosis of water. This results in a hollow ball of cells known as the blastocyst.[5][6] The blastocyst's outer cells will become the first embryonic epithelium (the trophectoderm). Some cells, however, will remain trapped in the interior and will become the inner cell mass (ICM), and are pluripotent. In mammals (except monotremes), the ICM will ultimately form the "embryo proper", while the trophectoderm will form the placenta and other extra-embryonic tissues. However, reptiles have a different ICM. The stages are longer and divided in 4 parts.[7][8][9][10]

     During each cleavage division the number of cell become double upto formation of morulla.
The rate of cleavage is govern by inverse ratio of yolk present in it.[Balfour law].

See also[edit]

References[edit]

  1. ^ Boklage, Charles E. (2009). How New Humans Are Made: Cells and Embryos, Twins and Chimeras, Left and Right, Mind/Self/Soul, Sex, and Schizophrenia. World Scientific. p. 217. ISBN 978-981-283-513-0. 
  2. ^ Sherman, Lawrence S. et al., ed. (2001). Human embryology (3rd ed.). Elsevier Health Sciences. p. 20. ISBN 978-0-443-06583-5. 
  3. ^ Chard, Tim & Lilford, Richard (1995). Basic sciences for obstetrics and gynaecology. Springer. p. 18. ISBN 978-3-540-19903-8. 
  4. ^ Mercader, Amparo et al. (2008). "Human embryo culture". In Lanza, Robert & Klimanskaya, Irina. Essential stem cell methods. Academic Press. p. 343. ISBN 978-0-12-374741-9. 
  5. ^ Patestas, Maria Antoniou & Gartner, Leslie P. (2006). A textbook of neuroanatomy. Wiley-Blackwell. p. 11. ISBN 978-1-4051-0340-4. 
  6. ^ Geisert, R.D. & Malayer, J.R. (2000). "Implantation: Blastocyst formation". In Hafez, B. & Hafez, Elsayed S.E. Reproduction in farm animals. Wiley-Blackwell. p. 118. ISBN 978-0-683-30577-7. 
  7. ^ Morali, Olivier G. et al. (2005). "Epithelium-Mesenchyme Transitions are Crucial Morphogenetic Events Occurring During Early Development". In Savagner, Pierre. Rise and fall of epithelial phenotype: concepts of epithelial-mesenchymal transition. Springer. p. 16. ISBN 978-0-306-48239-7. 
  8. ^ Birchmeier, Carmen et al. (1997). "Morphogenesis of epithelial cells". In Paul, Leendert C. & Issekutz, Thomas B. Adhesion molecules in health and disease. CRC Press. p. 208. ISBN 978-0-8247-9824-6. 
  9. ^ Nagy, András (2003). Manipulating the mouse embryo: a laboratory manual. CSHL Press. pp. 60–61. ISBN 978-0-87969-591-0. 
  10. ^ Connell, R.J. & Cutner, A. (2001). "Basic Embryology". In Cardozo, Linda & Staskin, David. Textbook of female urology and urogynaecology. Taylor & Francis. p. 92. ISBN 978-1-901865-05-9. 

Further reading[edit]