Dictionary

Developmental Biology classes began last week, and there are already words popping up which I get confused on because they appear so similar. The terms below are all derived from the Greek word blastos (βλαστός) – which means ‘sprout’.

Blastomeres: These are the cells formed from the mitotic divisions – during cleavage- of the zygote (fertilized egg). The divisions continuously occur to form the morula.

Blastula: This is a spherical body with a fluid-filled cavity which is developed from the morula stage. This is also known as blastosphere.

Blastocoel: This is the fluid filled cavity of the blastula.

Blastoderm: This is the single layered wall of cells of the blastula.

Blastocyst: This structure is present in the early embryonic development. It is thin-walled and hollow – contains a group of cells (inner cell mass). The embryo – tissues of the body - develops from the inner cell mass. The placenta and other supporting tissues required for the development of the fetus inside the uterus arises from the outer layer of the blastocyst (trophoblast).

Blastopore: At the gastrula stage, this is the invagination of the blastula which forms the opening of the archenteron. The archenteron is the central cavity of the gastrula, which develops into the intestinal or digestive cavity.

References:

"Blastomere - Definition of Blastomere in the Medical Dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia." Medical Dictionary. 2009. Received. 10 Sept. 2010. .

"Blastula - Definition of Blastula in the Medical Dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia." Medical Dictionary. 2009. Web. 10 Sept. 2010. .

"Blastocyst Definition - Medical Dictionary Definitions of Popular Medical Terms Easily Defined on MedTerms." 2003. Web. 10 Sept. 2010. .

"Blastopore - Definition of Blastopore in the Medical Dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia." Medical Dictionary. 2007. Web. 10 Sept. 2010. .

"Archenteron - Definition of Archenteron by the Free Online Dictionary, Thesaurus and Encyclopedia." Dictionary, Encyclopedia and Thesaurus - The Free Dictionary. 2009. Web. 10 Sept. 2010.