Establishment of brain ischemia model in tree shrew.

BACKGROUND: Tree shrew, as a kind of small and inexpensive animal between insectivores and primates with the general anatomy being similar to human, could be considered as developed animal model for brain ischemia (BI) study. However, there is no neural behavior scores criterion from tree shrew with BI up to now. METHODS: To produce BI model of tree shrew, a novel systematic neurobehavioral assessment scale, named as neural behavior scores (NBS) including aggressive behavior, seeking behavior, gait, startle reflex, high jump and warped-tail phenomenon was firstly established and used in this study. Moreover, magnetic resonance imaging (MRI) was performed on the first day after the operation to detect the imaging changes caused by ischemia. Then TTC, HE staining and immunofluorescent staining for GFAP and NeuN, were performed 24 h after surgery respectively. RESULTS: NBS in BI group were significantly higher than that of sham operation group at 1d, 3d, 5d and 7d after ischemia. Meanwhile, compared with the sham operation group, the T2 images demonstrated significant higher signal and local brain swelling after cerebral ischemia in tree shrews. The staining of TTC and HE showed apparent infarction and necrosis of the cerebral region, and most of neurons exhibited a shrink. CONCLUSION: We have successfully established the BI model of tree shrew, confirmed by NBS (a new developed method), MRI, HE staining, TTC staining and immunofluorescence staining. It is the first time to report a novel neurobehavioral assessment scale for BI in tree shrew.

c-Fos expression in the visual system of the tree shrew (Tupaia belangeri).

UNLABELLED: c-Fos is a nuclear phosphoprotein coded by the proto-oncogen c-fos which can be detected immunohistochemically after both physiological and pathological stimuli. This property is of great importance, because it offers a valuable tool for morphofunctional identification of activated neurons. We have studied the neuronal activity in the visual pathway of Tupaia belangeri within the following anatomical structures: retina, superior colliculus (SC), dorsal lateral geniculate nucleus (dLGN), pulvinar (Pu), parabigeminal (PBG) nucleus and primary visual cortex (V1) analyzing the c-Fos expression after exposing the tree shrews to different light stimuli (white light -control positive group-, green light, blue light and darkness conditions -control negative group-). Our findings suggest that in the retina, the ganglion cells and the cells of the inner nuclear layer respond better to blue and green light stimuli, when comparing the c-Fos expression between white, green, blue lights and darkness conditions. However, in the SC, dLGN, Pu, PBG nucleus and V1 another pattern of c-Fos expression is observed: a maximum expression for the control positive group, a minimum expression for the control negative group and intermediate expressions within the blue and green light groups. CONCLUSION: the expression levels of c-Fos protein are able to show significant differences between distinct light stimuli in all anatomical structures studied (retina, SC, dLGN, Pu, PBG and V1) of T. belangeri.

The monoptychic glands of the jugulo-sternal scent gland field of Tupaia: a TEM and SEM study.

The monoptychic 'apocrine' scent glands of the sternal region of two adult male Tupaia belangeri were studied by transmission and scanning electron microscopy, in order to assess the modes of release of their secretory products. In segments of the secretory tubules with a narrow lumen the epithelial cells are columnar and are firmly connected to each other by desmosomes and junctional complexes. Myoepithelial cells are interspersed between the secretory epithelium and the basement membrane. The cytoplasm of the secretory epithelial cells contains granular and agranular endoplasmic reticulum, mitochondria, Golgi apparatus, lysosomes and secretory granules. The free surface of the secretory epithelium is furnished with densely arranged microvilli. The apices of the cells protrude as dome-shaped extensions into the glandular lumen. At the tip of these extensions cellular processes of irregular shape are found. The surface of these processes shows no microvilli. They contain densely packed and dilated cisternae of agranular endoplasmic reticulum and free ribosomes. The constriction of the base of these processes and the occasional observation of a 'demarcation membrane' between a process and the secretory cell indicate that these secretory processes become detached from the secretory cells according to the apocrine mode of extrusion. Within the glandular lumen they break down and form secretion. Parallel to this apocrine extrusion the same cells produce secretory granules, the diameter of which measures 300-900 nm. The contents of these granules are released into the glandular lumen by exocytosis according to the eccrine mode of secretion. This resembles the situation in other mammals in which monoptychic glands release their secretory products by means of both apocrine and eccrine extrusion. Therefore monoptychic skin glands should not be classified into apocrine and eccrine glands. Our results corroborate Schaffer's (1927, 1940) more general classification of exocrine glands according to the nature of the secretory epithelium into monoptychic and polyptychic glands.