Mossy fiber terminals

Sandler R, Smith AD (1991) Coexistence of GABA and glutamate in mossy fiber terminals of the primate hippocampus an ultrastructural study. J Comp Neurol 303 177-192. 

Fig. 54. Ultrastructural localization of mGluR2/3 immunoreactivity in the granular layer of rat cerebellar cortex. Dense immunoreaction products accumulate in axon terminals of Golgi cells, which often make synaptic contacts (curved arrows) with possible granule cell dendrites around a mossy fiber terminal (MT) in the cerebellar glomerulus. Bar = 0.5 fm. Ohishi et al. (1994).

The distribution of ChAT-positive mossy fibers roughly corresponds to that of unipolar brush cells (see Section 3.6.3.), which raises the question whether these mossy fibers innervate these cells. Electron microscopic analysis of ChAT-immunoreactivity in the nodulus showed that a minority (10-20%) of ChAT-immunoreactive mossy fiber terminals synapse on brush cell profiles, and that a minority (10-30%) of the mossy fiber terminals contact unipolar brush cells that are immunoreactive for ChAT (Jaarsma, 1995c). 

Fig. 84. Illustrations of choline-acetyltransferase (ChAT)-like immunoreactivity in the rabbit cerebellum. A. Sagittal view of the rabbit cerebellum delineating the lobules according to Larsell (Larsell, 1970). Mean measurements of ChAT activity are indicated by numbers in parentheses. B. Magnified view of the ventral vermis. The vermis contains areas of ChAT-positive mossy fiber terminals (indicated by dots). These areas in lobules 1 and 9d are illustrated in C and D, respectively. E. View of the right paraflocculus of the rabbit. ChAT-like immunoreactivity and ChAT activity was highest in the ventral paraflocculus, particularly lobule 2. The numbers in parentheses are mean measurements of ChAT activity, expressed as mmol of Ach synthe-sized/hr. g tissue at 37°C, for each cerebellar lobule in six rabbits. Barmack et al. (1992a).

Fig. 114. EM autoradiogram of a spiny dendrite in the fastigial nucleus of the cat. A labelled mossy fiber terminal, originating from an injection of tritiated leucine into the nucleus reticularis tegmenti pontis, is densely filled with uniform spherical vesicles. Boutons with flattened vesicles form synaptic contacts on the same dendrite. Cat. Van der Want et al. (1987).

P2- (i.e. the B zone) extending into P3+ (Fig. 207). Matsushita et al. (1991), who mapped fibers from the cervical cord in Zebrin-I stained sections of rat cerebellum found less correspondence of the concentrations of rosettes with the borders of the im-munoreactive Purkinje cell zones. Ji and Hawkes (1994) showed that cuneocerebellar mossy fiber terminals are located between the concentrations of lumbar spinocerebellar mossy fiber rosettes in P1+, PI - and P2- of lobules II and III of the rat cerebellum (Fig. 207). A close correspondence between multiple patches of mossy fibers with vibrissal receptive fields and the Zebrin-negative P1-, P2- and P3- zones of lobule IX of the rat cerebellum, was observed by Chockkan and Hawkes (1994). 

Brodal A, Drablos PA (1963) Two types of mossy fiber terminals in the cerebellum and their regional distribution. J. Comp. Neurol, 121, 173-187. 

Ji Z, Hawkes R (1994) Topography of Purkinje cell compartments and mossy fiber terminal fields in lobules II and III of the rat cerebellar cortex spinocerebellar and cuneocerebellar projections. Neuroscience, 61, 935-954. 

Scheibel AB (1977) Sagittal organization of mossy fiber terminal systems in the cerebellum of the rat. Exp. Neurol, 57, 1067-1070. 

The hippocampus is sliced on a 200 pm polyester film of 2 x 3 cm (Pearl Paint) that has been extensively washed with 70% ethanol and air dned in a sterile hood Any plastic film can be used to support the hippocampus The film must be sterile and must resist being sliced by the tissue chopper blade There are consistent differences between cultures of the septal and temporal hippocampus that likely result from developmental gradients in the immature hippocampus (17), At postnatal d 10-11, the temporal end of the hippocampus is more mature than the septal end. Therefore, consistent differences can be observed between slice cultures originating from the temporal end or septal end. In particular, the mossy fiber projection differs between septal and temporal cultures (17) In septal cultures, there is mossy fiber sprouting mossy fiber terminals are found in the inner molecular layer of the dentate gyrus and the CA3 pyramidal cell layer. In temporal cultures, the mossy fiber projection is normal. This likely results in differences in slice culture excitability since epileptiform activity is more readily induced in septal cultures than temporal cultures (17). 

Conventional synaptosomes and mossy fiber terminals were isolated on density gradients (9,21) and T3 concentrations in the different fractions were measured as described in Fig. 2. Data points are mean concentration gradient units derived from two 2-pool brain homogenates error bars show range of differences in the replicate observations. Abscissa time after i.v. 125i x3 20 and 60 = minutes 3 and 11 - hours. 

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