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A. Morula and B. cross section of a blastula displaying the blastocoel and blastoderm of early animal embryonic development. Blastulation is the stage in early animal embryonic development that produces the blastula. In mammalian development, the blastula develops into the blastocyst with a differentiated inner cell mass and an outer trophectoderm.
At least four initial cell divisions occur, resulting in a dense ball of at least sixteen cells called the morula. In the early mouse embryo, the sister cells of each division remain connected during interphase by microtubule bridges. [7] The different cells derived from cleavage, up to the blastula stage, are called blastomeres.
Fish embryos go through a process called mid-blastula transition which is observed around the tenth cell division in some fish species. Once zygotic gene transcription starts, slow cell division begins and cell movements are observable. [4] During this time three cell populations become distinguished. The first population is the yolk syncytial ...
The blastomeres (4-cell stage) are arranged as a solid ball that when reaching a certain size, called a morula, (16-cell stage) takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb.
Lake whitefish are found throughout much of Canada and parts of the northern United States, including all of the Great Lakes. The lake whitefish is sometimes referred to as a "humpback" fish due to the small size of the head in relation to the length of the body. [3] [a] It is a valuable commercial fish, and also occasionally taken by sport ...
It possesses an inner cell mass (ICM) also known as the embryoblast which subsequently forms the embryo, and an outer layer of trophoblast cells called the trophectoderm. [1] [2] This layer surrounds the inner cell mass and a fluid-filled cavity or lumen known as the blastocoel. [3] In the late blastocyst, the trophectoderm is known as the ...
The blastocoel further expands and the inner cell mass becomes positioned on one side of the trophoblast cells forming a mammalian blastula, called a blastocyst. The axis formed by the inner cell mass and the blastocoel is the first axis of symmetry of mammalian embryo and determines its attachment point to the uterus.
Cavitation is the formation of the blastocoel, a fluid-filled cavity that defines the blastula, or in mammals the blastocyst. [1] After fertilization , cell division of the zygote occurs which results in the formation of a solid ball of cells ( blastomeres ) called the morula .