1/29/2024 0 Comments Red rumped agouti adaptations![]() This is a medium sized rodent, larger than a guinea pig and with longer legs. The analysis is based on a description of the placenta of the red-rumped agouti ( Dasyprocta leporina). In this paper we review the structure of the subplacenta and examine possible functional correlates. Beneath this is a structure known as the subplacenta that is unique to the hystricognath rodents. The lobules are separated by interlobular trophoblast that is the counterpart of the spongy layer found in the placenta of other rodents. The exchange area or labyrinth is lobulated, an adaptation that allows an increase in the total exchange area and helps to support the larger fetus at the end of gestation. The hystricognath placenta has a number of distinctive features. This reproductive strategy requires a lower rate of energy consumption and is well suited to an herbivorous diet. The newborn is well developed with open eyes and a full coat of hair. They differ from other rodents in giving birth to precocial young. At this time they were able to capitalize upon the emergence of grasslands for which they were well adapted in a number of ways. The hystricognath rodents (Suborder Hystricomorpha, Infraorder Hystricognathi ) appeared in the Eocene and underwent an extensive radiation in the Miocene. Our findings are consistent with this interpretation, but suggest that hormone secretion is directed towards the fetal circulation rather than the maternal tissues. The functions that have been attributed to the subplacenta include hormone production. Within it the vessels pursue a tortuous course with sinusoidal dilatations and constrictions. The subplacenta is supplied entirely from the fetal circulation. This is probably the amylase-resistant PAS-positive material identified by histochemistry. The syncytial cytoplasm contains electron-dense granules. Microvilli project into these lacunae from the plasma membrane of the syncytiotrophoblast. The syncytiotrophoblast surrounds an extensive system of lacunae. The basal membrane of these cells is often close to fetal blood vessels. There are prominent intercellular spaces between the cytotrophoblast cells. Clusters of multinuclear giant cells occur in the transition zone between the subplacenta and decidua. Beneath this is found syncytiotrophoblast. In the subplacenta, lamellae of connective tissue support a layer of mononuclear cytotrophoblast cells. In addition, to study the microvasculature of the subplacenta, vessel casts were inspected by scanning electron microscopy Results Placentae were collected from early in midgestation to near term of pregnancy and examined by standard histological techniques, immunohistochemistry and transmission electron microscopy. We here describe the subplacenta of the red-rumped agouti and examine the possible functional correlates of this structure. Beneath them, however, is a structure unique to hystricognath rodents called the subplacenta. These correspond to the labyrinthine and spongy zones of other rodent placentae. Furthermore, the gestation period averages 104 days, and females are able to produce two newborns per litter.Hystricognath rodents have a lobed placenta, comprising labyrinthine exchange areas and interlobular trophoblast. One estrus period can last for 24 hours while the estrous cycle can last between 30 and 34 days. Also, they are considered to be seasonally polyestrous, meaning the females can go through more than one period of estrus in a single year. The female black agouti is capable of breeding year-round. In some areas, they construct burrows among limestone boulders, along river banks, or under the roots of trees. Like other agoutis, the black agouti is diurnal, lives alone or in pairs, and feeds on fruits and nuts. It is overall black grizzled white, and the throat is white. Agoutis live in close proximity to water, being found on the banks of all types of streams. It is found at altitudes of 2,000 metres (6,600 ft) and above. ![]() In Peru, they are confined to the Amazonian region where they are found in all parts of the low selva zone and many parts of the high selva zone. They are found in forests, thick brush, savannas, and cultivated areas. There is also a disjunct population in the Magdalena River Valley of northern Colombia. It is found in the northwestern Amazon in southern Venezuela, eastern Colombia, eastern Ecuador, western Brazil and northeastern Peru. The black agouti ( Dasyprocta fuliginosa) is a South American species of agouti from the family Dasyproctidae.
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