Granular layer

These cells are nsually pigmented due to the transfer of melanin (from melanocytes), which is regularly recycled into keratinocytes of the basal layer. Melanin has the purpose of absorbing noxious ultraviolet rays, sparing the nuclear DNA. The keratinocytes are attached to the basal membrane on which they rest by the hemidesmosomes situated facing the interior of the skin, or perhaps laterally, and are therefore attached to their neighboring cells by the desmosomes. 

The basal membrane, found at the junction between the epidermis and the dermis, undulates due to the invaginations of the papillary dermis. The basal membrane separates the basal layer from the dermis, and it is itself composed of many subtle molecular layers (Fig. 2.3) (a component notable by being laminated by type IV collagen). 

This is called the layer of spiny cells due to their appearance on optical microscopy of appendages between cells which resemble spines and which are in fact the points of attachment that exist between the cells, placed in evidence by 

This layer is composed of one to three layers of flattened cells of which the cytoplasm is filled with keratohyalin basophilic granules. These granules are transformed into keratin in the superficial corneal layer. 

This layer, which makes up the most external interface of the body, is composed of cells having lost nuclei and intracellular organelles and are filled with keratin filaments. The keratin filaments are aggregated by the threads and interior tissue of the cytoplasm into a solid network which solidifies the plasma membrane and is 

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Localisation CA/S Hippocampus (CA1, CA3, DG), cortex, cerebellum (granular layer), olfactory bulb, habenula, spinal cord CA/S Caudate putamen, olfactory tubercle, nucleus accumbens, cortex, hippocampus (CA1, CA3, DG) CA/S Hippocampus (CA1, CA2), hypothalamus, thalamus, superior colliculus, raphe nuclei... 

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... 

PI. 2.4 Bulbar layers horizontal section of MOB + AOB (outlined) in Mouse Lemur (Microcebus murinus). g = Glomerular m = Mitral and gr = Granular layers (courtesy of Alain Schilling ). 

Mice exposed continuously to 100 ppm or intermittently to 400 ppm for 11 days had histopathologic evidence of brain lesions characterized by degeneration and atrophy of the granular layer of the cerebellum. Daily exposure of mice to 1000 ppm for 2 years induced a functional limb muscle impairment and atrophy of the spleen. At 2400ppm administered daily, there were renal and hematopoietic effects and the mice were moribund by day 9. For rats exposed to 3 500 ppm 6 hours/day for up to 12 days, clinical signs included severe diarrhea, incoordination of the forelimbs, and, in a few animals, hind limb paralysis and convulsions. ... 

Normal human epidermis exhibited homogeneous caspase 14 staining in spinous and granular layers and moderate staining in the basal layer, with evidence of nuclear... 

Fleckman, P. and Brumbaigh, S., Absence of the granular layer and keratohyaline define a morphologically distinct subset of individuals with ichthyosis vulgaris, Exp. Dermatol., 11, 327, 2002. 

Hyaluronan is most prominent in the upper spinous and granular layers of the epidermis, where most of it is extracellular. The basal layer has HA, but it is predominantly intracellular, and is not easily leeched out during aqueous fixation. Presumably, basal keratinocyte HA is involved in cell cycling events, while the secreted HA in the upper outer layers of the epidermis are mechanisms for disassociation and eventual sloughing of cells. 

The EFA are found predominantly within the epidermal phospholipids (e.g., phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine), with the pattern of incorporation varying between fatty acids. They are also present in small amounts in cholesterol, and importantly, are found linked with ceramides in the granular layer and stratum corneum, where they play a critical role in barrier function. The most abundant EFA in the skin are LA and A A, comprising approximately 12 and 3.5%, respectively of human epidermal fatty acids.12 ALA is known to accumulate in the skin of animals, but is found in much lower levels than LA.13... 

Although rodent buccal mucosa is reported to consist of both keratinized and non-keratinized striated epithelia, no evidence for the latter was obtained in the present study. In all rodents examined, heavily keratinized striated epithelia were observed on the inner central cheek (see Figure 1 for rat). Mucosal sections exhibited characteristic epithelial cell differentiation with cells becoming progressively flatter and forming a granular layer with increasing distance from the basal cell layer. The outer... 

Figure 7.1 Structure of non-keratinized oral epithelium, as found in the sublingual and buccal regions of the oral cavity. (Note keratinized epithelium has a broadly similar structure however, the epithelial cell layers comprise basal layer, prickle cell layer, granular layer and keratinized layer)...

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