The blastula is a hollow ball of cells organized into an epithelial monolayer.
Formation of Blastula. By Dr Ananya Mandal, MD. The process of embryogenesis begins when an egg or ovum is fertilized by a sperm cell to form a zygote. This zygote then undergoes mitotic division, a process that does not result in any significant growth but creates a multicellular cluster called a blastula.  gastrula. n, pl-las or-lae (-ˌliː). 1. (Biology) a saclike animal embryo consisting of three layers of cells (ectoderm, mesoderm, and endoderm) surrounding a central cavity (archenteron) with a small opening (blastopore) to the exterior. See also ectoderm, mesoderm, endoderm.  blastula. An early embryo nic form produced by cleavage of a fertilized ovum and usually consisting of a single layer of cells surrounding a fluid-filled spherical cavity. blastula. spherical, hollow mass of cells resulting from the division of the egg. From Wikipedia, the free encyclopedia. Jump to: navigation, search ... The blastula is an early stage of embryo nic development in animals. It is produced by cleavage of a fertilized ovum and consisting of a spherical layer of cells surrounding a fluid-filled cavity. gastrula. an embryo in the stage following the blastula stage; the simplest type consists of two layers of cells, the ectoderm and entoderm, which have invaginated to form the archenteron and an opening, the blastopore. 1  Facebook. 2  Twitter.  blastula. the usually spherical body produced by cleavage of a fertilized ovum (zygote), consisting of a single layer of cells (blastoderm) surrounding a fluid-filled cavity (blastocoele); it follows the morula stage. (blas'tū-lă), blastula. the usually spherical body produced by cleavage of a fertilized ovum, consisting of a single layer of cells (blastoderm) surrounding a fluid-filled cavity (blastocoele); it follows the morula stage. Medical Definition of BLASTULA. : an early metazoan embryo typically having the form of a hollow fluid-filled rounded cavity bounded by a single layer of cells—compare gastrula, morula. — blas·tu·lar \-lər\ adjective. Definition of BLASTULA. : an early metazoan embryo typically having the form of a hollow fluid-filled rounded cavity bounded by a single layer of cells — compare gastrula, morula. — blas·tu·la·tion \ˌblas-chə-ˈlā-shən\ noun. See blastula defined for kids. ADVERTISEMENT blastula. [blas′tyələ]. Etymology: Gk, blastos, germ. an early stage of the process through which a zygote develops into an embryo, characterized by a fluid-filled sphere formed by a single layer of cells. The spheric layer of cells is called a blastoderm; the fluid-filled cavity is the blastocoele. blastula. the usually spherical body produced by cleavage of a fertilized ovum, consisting of a single layer of cells (blastoderm) surrounding a fluid-filled cavity (blastocoele); it follows the morula stage. Cleavage-Blastula Structure. The blastula is a hollow ball of cells organized into an epithelial monolayer. Midway through the blastula stage, the embryo secretes hatching enzyme, which results in proteolytic degradation of the fertilization envelope. 
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what is the blastula