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In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell (spermatozoon). [1] Once fertilized, the ovum becomes a single diploid cell known as a zygote.
These cellular movements can be directed by external stimuli, a phenomenon known as taxis. Examples include chemotaxis (movement along chemical gradients) and phototaxis (movement in response to light). Motility also includes physiological processes like gastrointestinal movements and peristalsis.
For example, studies frequently combine EMG and kinematics to determine motor pattern, the series of electrical and kinematic events that produce a given movement. Optogenetic perturbations are also frequently combined with kinematics to study how locomotor behaviors and tasks are affected by the activity of a certain group of neurons.
Frog (Xenopus), as well as other amphibian, gastrulation serves as an excellent example of the role of convergent extension in embryogenesis. During gastrulation in frogs, the driving force of convergent extension is the morphogenic activity of the presumptive dorsal mesodermal cells; this activity is driven by the mesenchymal cells that lie ...
Pharotaxis is the movement to a specific location in response to learned or conditioned stimuli, or navigation by means of landmarks. [20] [21] Phonotaxis is the movement of an organism in response to sound. Phototaxis is the movement of an organism in response to light: that is, the response to variation in light intensity and direction.
The inborn spirit causes movement in the body by expanding and contracting. Each of these implies not only a movement but also a change in the degree of power and strength of the animal. "when it contracts it is without force, and one and the same cause gives it force and enables it to thrust" (703a23).
Epiboly in zebrafish is the first coordinated cell movement, beginning at the dome stage late in the blastula period and continuing throughout gastrulation. [3] At this point the zebrafish embryo contains three portions: an epithelial monolayer known as the enveloping layer (EVL), a yolk syncytial layer (YSL) which is a membrane-enclosed group of nuclei that lie on top of the yolk cell, and ...
Cell migration is a central process in the development and maintenance of multicellular organisms.Tissue formation during embryonic development, wound healing and immune responses all require the orchestrated movement of cells in particular directions to specific locations.