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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 ...
The three traditional modes of reproduction are: [1] Oviparity, taken to be the ancestral condition, where either unfertilised oocytes or fertilised eggs are spawned. [1] Viviparity, including any mechanism where young are born live, or where the development of the young is supported by either parent in or on any part of their body. [1]
In cases where the insect remains active, feeding is reduced and reproductive development is slowed or halted. Embryonic diapause , a somewhat similar phenomenon, occurs in over 130 species of mammals, possibly even in humans, [ 3 ] [ 4 ] and in the embryos of many of the oviparous species of fish in the order Cyprinodontiformes .
The transmission of these viruses depends on the movements of aphids between different parts of a plant, between nearby plants, and further afield. In this respect, the probing behavior of an aphid tasting a host is more damaging than lengthy aphid feeding and reproduction by stay-put individuals.
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]
An intromittent organ is any external organ of a male organism that is specialized to deliver sperm during copulation. [1] [2] Intromittent organs are found most often in terrestrial species, as most non-mammalian aquatic species fertilize their eggs externally, although there are exceptions.
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.
In domestic animals, luteolysis is initiated by the hormones prostaglandin F2alpha and oxytocin and is dependent on the presence of the uterus. In sheep, communication between the pars nervosa (posterior lobe of the pituitary gland), corpus luteum, and the uterus endometrium via the circulatory system is required for luteolysis.