Platypus and Tachyglossus sperm bundles have a forward velocity about 3-times that of individual sperm when diluted and incubated in vitro. Frank Grützner, in Encyclopedia of Reproduction (Second Edition), 2018 Sperm Capacitation 3V, third ventricle BST, bed nuclei of the stria terminalis chp, choroid plexus primordium CPu, caudatoputamen Dien, diencephalon GP, globus pallidus hi, hippocampal primordium ic, internal capsule lge, lateral ganglionic eminence LV, lateral ventricle m5, motor root of trigeminal nerve mge, medial ganglionic eminence OptRe, optic recess of third ventricle pit, pituitary smt, stria medullaris thalami. Even before hatching (B), the cerebral cortex (cx) of the short-beaked echidna has begin to show folding and a distinct preplate layer (PrePl) with postmitotic neurons, whereas in the newly hatched platypus (C) the cx is still smooth and consists of only a ventricular germinal zone. Note the striking size of the trigeminal ganglion (5Gn) in the newly hatched platypus (A). Photomicrographs of frontal sections through the developing brain of a platypus (A,C) and a short-beaked echidna (B) around the time of hatching. They went on to argue that such an early developmental divergence is more consistent with the notion that the platypus and echidna have both diverged from an ancestor with rudimentary electroreception and/or trigeminal specialization, rather than the contention that the echidna is derived from a platypus-like ancestor.įigure 4. interpreted these findings to indicate that the trigeminal pathways in the short-beaked echidna and the platypus follow very different developmental trajectories from the earliest embryonic appearance of epidermal specialization. This difference in size continues throughout posthatching development. The cross-sectional areas of the trigeminal divisions and the volume of the trigeminal ganglion itself were also very different between the two species at embryonic ages very large in the platypus ( Fig. 4A), but comparable in size to therians in the echidna. These were linear in the platypus, but focal at the snout tip in the echidna. (2012) found that each monotreme showed a characteristic and different pattern of distribution of developing epidermal sensory gland specializations (electroreceptor primordia) from the time of hatching. This naturally raises the question of when this distinct pattern of peripheral trigeminal receptors appears in the two species during development. The platypus has a distinctive linear pattern of mucous sensory glands on its bill, whereas the short-beaked echidna has a sensory gland hot spot on its beak tip. The platypus and echidnas have very different distributions of sensory glands and mechanoreceptors in their bills or beaks. Treatment is symptomatic and requires medical attention for pain relief functional impairment of the affected envenomation area can also persist and requires medical monitoring. The envenomation is also associated with an extended hyperalgesia. The toxin is a C-type natriuretic peptide, and has been associated with calcium-dependent nociceptor action. The pain is associated with mast cell degeneration.
Although the defensin-like proteins are not lethal to humans, victims experience such excruciating pain that they may become incapacitated. Three of these proteins are unique to the platypus. The ankle spurs of male platypuses produce a venom comprised of defensin-like proteins, nerve growth factor, and natriuretic peptides. Platypuses do not have teeth, but the males are venomous, with stingers on their rear feet.
The platypus has webbed feet, a large duck-billed snout, and a beaverlike tail. The platypus is a monotreme mammal found in Australia and Tasmania, and is one of the very few venomous mammals. Broderick, in Encyclopedia of Toxicology (Third Edition), 2014 Platypus Introduction
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