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Viviparous Definition A viviparous animal gives birth to live young. Growing embryos are nourished by special organs in the parents as they develop. Matrotrophy is the condition in which the embryo receives nutrients directly from the mother, rather than from the yolk. The difference between ovoviviparity and viviparity is that viviparous animals feed their embryos … Read more

Cardiac Muscle Definition Cardiac muscle, also known as heart muscle, is the layer of muscle tissue which lies between the endocardium and epicardium. These inner and outer layers of the heart, respectively, surround the cardiac muscle tissue and separate it from the blood and other organs. Cardiac muscle is made from sheets of cardiac muscle … Read more

Deletion Mutation Definition A deletion mutation occurs when nucleotides are removed from the genome during DNA replication. Deletion mutations can remove a single nucleotide, or entire sequences of nucleotides. DNA deletions occur when the enzyme that synthesizes new DNA slips on the template DNA strand, effectively missing a nucleotide.  For DNA replication to occur, polymerase … Read more

The Basics Shoebill storks (Balaeniceps rex) are large, broad birds found in swamps and wetlands of Central and East Africa. It has a large body, huge wings, and a shoe-shaped bill. There is also some evidence that this prehistoric-looking bird is related to the now-extinct dinosaurs! Their plumage consists of a dark grey, blue-grey, or … Read more

Desmosomes Definition The desmosome is a type of anchoring junction that connects adjacent cells in animal tissues. Around all cells are anchoring junctions, which bind adjacent cells together. A desmosome has intermediate filaments underneath that anchor the junction, while an adherens junction is anchored by microfilaments. Microfilaments and intermediate filaments both make up the cytoskeleton … Read more

Hyaline Cartilage Definition In the human body, hyaline cartilage is found in areas such as the nose, ears, and trachea. Hyaline cartilage is a glossy, greyish-white tissue with a uniform appearance, and the word hyaline means “glass-like”. In addition to elastic cartilage and fibrocartilage, it is one of three types of cartilage. In the body, … Read more

Deciduous Trees Definition Deciduous trees shed their leaves towards the conclusion of their growth season. This happens in the fall in temperate deciduous woods, and in the dry season in tropical and subtropical deciduous forests. The term deciduous originates from the Latin word decidere, meaning “to fall off.” The term for leaf loss is abscission.  … Read more

Organs within the endocrine system include the brain, pancreas, ovaries, testicles, and thyroid gland. To regulate many of the body’s functions, these organs secrete hormones into the bloodstream.  The pituitary gland, for example, releases thyroid stimulating hormone, also known as TSH, which regulates many of these glands. Thyroxine is produced by the thyroid gland in … Read more