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Embryonic diapause [a] (delayed implantation in mammals) is a reproductive strategy used by a number of animal species across different biological classes.In more than 130 types of mammals where this takes place, the process occurs at the blastocyst stage of embryonic development, [1] and is characterized by a dramatic reduction or complete cessation of mitotic activity, arresting most often ...
In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization. The fertilized egg cell is known as the zygote. [2] [5]
A beetle leg. An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface appendages.
For example, structures may be described relative to the anterior superior iliac spine, the medial malleolus or the medial epicondyle. Anatomical lines are used to describe anatomical location. For example, the mid-clavicular line is used as part of the cardiac exam in medicine to feel the apex beat of the heart.
Ape skeletons. A display at the Museum of Zoology, University of Cambridge.From left to right: Bornean orangutan, two western gorillas, chimpanzee, human. The evolution of human bipedalism, which began in primates approximately four million years ago, [1] or as early as seven million years ago with Sahelanthropus, [2] [3] or approximately twelve million years ago with Danuvius guggenmosi, has ...
Bilateria (/ ˌ b aɪ l ə ˈ t ɪər i ə /) [5] is a large clade or infrakingdom of animals called bilaterians (/ ˌ b aɪ l ə ˈ t ɪər i ə n /), [6] characterised by bilateral symmetry (i.e. having a left and a right side that are mirror images of each other) during embryonic development.
The full development of Oikopleura dioica and the fate of its cell lineages have been well-documented, providing insight into larvacean anatomy. [11] Being a model organism, most of our knowledge on larvaceans comes from this specific taxon. Variations in body shape and anatomy exist between families, [12] although the general body plan stays ...
Modern groups of animals can be grouped by the arrangement of their body structures, so are said to possess different body plans. A body plan, Bauplan (pl. German: Baupläne), or ground plan is a set of morphological features common to many members of a phylum of animals. [1] The vertebrates share one body plan, while invertebrates have many.