![]() ![]() The entorhinal cortex is easily identified by the presence of a lamina dissecans (Fig. The primary auditory cortex is also difficult to identify definitively without electrophysiology and has been labelled here based on extrapolation from the cortical sensory maps of other diprotodontid species (e.g. Putative body representation areas have been labelled on Fig 1b, but these are based on extrapolation from other diprotodontids and have not been confirmed by electrophysiology. The primary somatosensory cortex lacks the barrel structures seen in the brains of macropod and phalangerid diprotodontids (Weller, 1972 Weller and Haight, 1973 Weller, 1993 Waite et al., 1991). 1b in Plate 1), but the isocortical layers are thin and less distinct in other cortical regions and the primary auditory cortex has only an indistinct layer 4 (Fig. 2a in Plate 2) and primary somatosensory cortices (Fig. 1a in Plate 1) and the granular layer 4 is also prominent in the primary visual (Fig. The motor cortex has a prominent layer 5 with large pyramidal neurons (see Fig. The cortex is laminated like all other mammals, but the cytoarchitectural differentiation between the six isocortical layers is less obvious than in other marsupials and eutherians with a similarly sized brain. The lateral ventricles are large and the cerebral cortex is relatively thin for the endocranial volume. The cerebral cortex of the koala is relatively smooth (lissencephalic) for its size. The cartoon in each plate shows the position of the section in the rostrocaudal extent of the cerebral hemisphere. Boundaries between putative cortical regions have been indicated by filled wedges. The section images have been placed in Adobe Illustrator 2021 and labelled using a modified Paxinos/Watson system of brain nomenclature. Multiplying the section number by 0.03 mm will give the distance in mm from the rostral end of the olfactory bulb. Section numbers refer to the sequence from the rostral tip of the olfactory bulb. The sections were photographed with an Olympus BHS2 microscope using a 4x objective and the images stitched with Adobe Photoshop CS5.1 to create montages of the isocortex, and limbic and olfactory allocortex. The brain had been embedded, sectioned at a thickness of 30 µm and stained with thionin. The adult specimen depicted here (0505_354) is from the Nelson Collection held at the Australian National Wildlife Collection in Australian Capital Territory, Australia. The eucalyptus diet of the koala is low in nutrients and high in turpenes, phenols and fibre, so the mammal leads a low-energy lifestyle and is highly sedentary, sleeping as much as 20 hours per day. The species is found down the eastern and southern side of mainland Australia from Queensland to South Australia. The koala ( Phascolarctos cinereus) is an arboreal, diprotodontid marsupial, which leads a solitary and mostly nocturnal life. Cerebral Cortex of the Koala ( Phascolarctos cinereus) ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |