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Similar to mammals, fertilization of the avian ovum occurs in the oviduct. From there the blastodisc, a small cluster of cells in the animal pole of the egg, then undergoes discoidal meroblastic cleavage. The blastoderm develops into the epiblast and hypoblast and it is between these layers that the blastocoel will form.
The blastula (from Greek βλαστός (blastos meaning sprout)) is a hollow sphere of cells known as blastomeres surrounding an inner fluid-filled cavity called the blastocoel. [ 1 ] [ 2 ] Embryonic development begins with a sperm fertilizing an egg cell to become a zygote , which undergoes many cleavages to develop into a ball of cells ...
Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million in total. Animals range in size from 8.5 millionths of a metre to 33.6 metres (110 ft) long and have complex interactions with each other and their environments, forming intricate food webs .
The Catalogue of Life is an online database that provides an index of known species of animals, plants, fungi, and microorganisms. It was created in 2001 as a partnership between the global Species 2000 and the American Integrated Taxonomic Information System .
The ligand for CD40. This is a costimulatory molecule that plays many roles, best known for activating B cells but also known to induce the activation of an APC in association with T cell receptor stimulation by MHC molecules on the APC. CD155: The poliovirus receptor, a protein that in humans that is encoded by the PVR gene. Also known as ...
The type species of the genus Mini, which are extremely small (8–15 mm (0.3–0.6 in)) frogs endemic to Madagascar, among the smallest vertebrates known to science. Mus bufo (Thomas, 1906) - family Muridae. The toad mouse, found in Burundi, Democratic Republic of the Congo, Rwanda, and Uganda.
The following is a list of the classes in each phylum of the kingdom Animalia. There are 107 classes of animals in 33 phyla in this list. However, different sources give different numbers of classes and phyla. For example, Protura, Diplura, and Collembola are often considered to be the three orders in the class Entognatha. This list should by ...
A microbial colony is defined as a visible cluster of microorganisms growing on the surface of or within a solid medium, presumably cultured from a single cell. [11] Because the colony is clonal , with all organisms in it descending from a single ancestor (assuming no contamination ), they are genetically identical, except for any mutations ...