External granule-cell layer

Fig. 91. Bergmann glial fibers in the rat cerebella of various ages. PAP immunocytochemistry with anti-GFAP antiserum. The ages of the rats are 3, 5, 8 days and 30 months in A, B, C and D, respectively. EG, external granule cell layer M, molecular layer G, granule cell layer. Scale bars = 20//m. De Bias and Cherwinski (1985).

Abbreviations GL, glomerular layer EPL, external plexiform layer MCL, mitral cell layer IPL, internal plexiform layer GCL, granule cell layer EZ, ependymal zone. 

EP = exposed group (n = 3). OB = olfactory bulb OP = olfactory peduncle ON = olfactory nerve G1 = glomerular layer Epl = external plexi-form layer. Mi = mitral cell layer Ipl = internal plexiform layer GrO = granule cell layer of olfactory bulb Md = medullary layer GrA = granule cell layer of accessory olfactory bulb AOB = accessory olfactory bulb AOE = anterior olfactory nucleus external part AOL = anterior olfactory nucleus, lateral part lo = lateral tract. (Reprinted from Wang et alP 2007 Humana Press Inc.)... 

Orona E, Scott JW, Rainer EC, 1983, Different granule cell populations innervate superficial and deep regions of the external plexiform layer in rat olfactory bulb. J Comp Neurol 217 227-237. 

Fig. 28. Developmental expression of protein kinase C (PKC) isoenzymes in rat cerebellum. Immunofluores-cent staining of cerebellar cortex by antibodies specific for PKC 1, corresponding to PKCr (panels A, B and C), PKC (panels D, E and F) and PKCa (panels G, H and I), Sagittal sections of cerebellum of 1-week-old (A, D and G), 2-week-old (B, E and H) and 3-week-old (C, F and I) rats were used. PKCr antibody stained mainly the Purkinje ceil bodies and dendrites throughout the development. PKC/8 antibody stained the cerebellar granule cells in the external germinal layer (EGL) of the 1- and 2-week-old rats and mainly the granular layer of the 3-week-old rats. PKCa antibody stained both granule cells and Purkinje cells throughout the development. Fluang et al. (1991).

Immediately deep to the glomeruli is a layer with a relatively low cell density but a very dense neuropil, the external plexiform layer (EPL). Golgi-stained sections reveal that the predominant neural elements in this layer are the dendrites of mitral/tufted and granule cells. The principal neuron types in EPL are external, middle (Fig. 12B) and deep tufted cells, named according to their relative depth in EPL, and the Van Ge-huchten cells. 

Granule cells, quantitatively the largest contingent of neurons formed from the external granular layer (EGL), initiate neurite outgrowth after permanently withdrawing from their division cycle, which takes place in the proliferative zone located in the outer part of the EGL. These cells then... 

---