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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.
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 ...
The inward migration of these cells, known as bottle cells, leads to the formation of the archenteron, a process analogous to that observed in the gastrulation of sea urchins. Gastrulation in frogs commences in the marginal zone— the region encircling the blastula's equator where the animal and vegetal hemispheres meet—differing from sea ...
Coregonus is a diverse genus of fish in the salmon family ().The Coregonus species are known as whitefishes.The genus contains at least 68 described extant taxa, but the true number of species is a matter of debate.
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 .
This is an embryo 4 hours after fertilization before it has undergone MBT. 3 layers are present: yolk syncytial layer (YSL), enveloping layer (EVL), and deep cells (DEL). Before the embryo undergoes the midblastula transition it is in a state of fast and constant replication of cells. [1] The cell cycle is very short. The cells in the zygote ...
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.
There is much variation among the European whitefish forms, but in general they have a tapered body, a slightly protruding upper jaw and a fleshy dorsal fin that is typical of the salmon family. The snout is short and tapered, a fact that distinguishes this species from the two other North European Coregonus species, vendace ( Coregonus albula ...