External granular layer

Reiss K, Mentlein R, Sievers J, Hartmann D (2002) Stromal cell-derived factor 1 is secreted by meningeal cells and acts as chemotactic factor on neuronal stem cells of the cerebellar external granular layer. Neuroscience 115 295-305... 

Appendageal structures commonly found within the skin are the hairs, hair follicles, associated sebaceous glands, apocrine and eccrine sweat glands, and arrector pili muscles. Hairs are formed by epidermal invaginations. These keratinized structures traverse the dermis and may extend into the hypodermis. The free part of the hair above the surface of the skin is the hair shaft, and the part deep within the dermis is the hair root, which forms an expanded knob-like structure called the hair bulb. This is composed of a matrix of epithelial cells in different stages of differentiation. Hair is composed of three concentric epithelial cell layers the outermost thin cuticle, a densely packed keratinized cortex, and a central medulla of cuboidal cells. The hair follicle consists of four major components (1) internal root sheath (internal root sheath cuticle, granular layer, pale epithelial layer) (2) external root sheath (several layers similar to the epidermis) (3) dermal papilla (connective tissue) and (4) hair matrix (comparable to the stratum basale of the epidermis). 

Because papillomaviruses are specialized for replication in external ep-ithelia, infection is usually confined to the epithelium exposed to the external environment and does not result in systemic dissemination of the virus. While viral replication occurs in differentiated epithelial cells in the upper epidermal layer, viral particles are also often located in the deep epidermal basal layer. The epidermis becomes thickened and hyperkera-totic, and keratinocytes (keratin-containing cells) in the epidermal granular layer become vacuolated as a result of viral infection. The mechanisms by which virions penetrate the stratum corneum and infect viable keratinocytes is poorly understood, as there is a lack of practical in vitro culture systems available for these viruses to serve as study aids. 

Fig. J. Glutaminase-immunoreactive neurons in layer V of the neocortex (ti), mitral cell layer of the olfactory bulb (b), lateral geniculate nucleus (c) and pontine nuclei (d). The method for immunostaining is described in the legend of Fig. I. EP = external plexiform layer IG = internal granular layer M = mitral cell layer. Modified from Kaneko (1991).

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).

Fig. 190. Distribution of CRF and CGRP-immunoreactive climbing fibers in P7 mouse cerebellum (A-C) and in neurons of the inferior olive (D-F). CRF-immunoreactive climbing fibers and neurons are indicated by dots, CGRP-immunoreactive climbing fibers and neurons by open circles, a, b and c = subnuclei a, b and c of the medial accessory olive beta -i- group beta Cl, C2 = Crus I and II DAO = dorsal accessory olive dc = dorsal cap EGL.ML = external granular layer and molecular layer F = flocculus IGL = internal granular layer PF = paraflocculus MAO = medial accessory olive PO = principal olive PL = Purkinje cell layer. Redrawn from Yamano and Tohyama (1993).

Marani E, Tetteroo PAT (1983) A longitudinal band-pattern for the monoclonal human granulocyte antibody B4,3 in the cerebellar external granular layer of the immature rabbit. Histochemistry, 78, 157-161. 

Hatten, M.E., Furie, M.B. and Rifkin, D.B. (1982) Binding of developing mouse cerebellar cells to fibronectin a possible mechanism for the formation of the external granular layer. J. Neurosci. 2 1195-1206. 

Controls the rate of migration of granular cells from the external germinal layer to the internal granular layer... 

In 1965, Legrand and co-workers reported effects of neonatal hypothyroidism on cerebellar development in the rat, which suggested that thyroid hormones are required for the normal rate and amount of cell acquisition from an actively proliferating germinal zone, the external granular layer. 

In the newborn rat, the external granular layer (EGL), located on the surface of the cerebellum, consists of a... 

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... 

Lauder, J.M., 1977, The effects of early hypo- and hyperthyroidism on the development of rat cerebellar cortex. III. Kinetics of cell proliferation in the external granular layer. Brain Res.. 126 31. 

Fig. 4 Single immunoperoxidase staining for LC3B at P11, PI 7, and P30. At P11, the ML of control rats is intensely immunopositive (a). After treatment with platinum compounds, there are no obvious differences in immunoreactivity (b, c). At PI 7, there is a reduction of immunoreactivity in Purkinje cells of controls (d) and that becomes much more evident after treatment with cisPt (e) and PtAcacDMS (f). At P30, immunoreactivity has completely disappeared from the ML. In parallel, a weak labeling appears in the Purkinje neuron cytoplasm and main dendrites (g-i). Abbreviations-. EGL external granular layer, IGL internal granular layer, ML molecular layer. Scale bars 50 pm (e-i) 100 pm (a-f)...

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