Stratum reticulare

Figure 10.12 Theoretical estimation of the intracutaneous P02 profile. SC, stratum corneum ED, epidermis SP, papillary dermis SR, reticular dermis. Reprinted with permission from Ref. 168. Copyright 2002 Blackwell Publishing.

Figure 3.7. Structure of skin. Skin is composed of two layers the dermis and epidermis. Epidermis is a stratified squamous epithelium containing stratum corneum, stratum spinosum, and stratum basale (basal cell layer). The dermis contains papillary and reticular layers and a subcutaneous layer containing fat, blood vessels, and skeletal muscle.

With EMLA, liposoluble anesthetic molecules penetrate the stratum comeum and the rest of the epidermal barrier and soon reach the skin nerve endings. The phenol, which is also liposoluble, can get through the epidermis more quickly. On the surface the shorter contact time between the epidermis and the phenol could reduce epidermal liquefaction. Deep down, a higher concentration of phenol in the reticular dermis could cause the formation of retractile scar tissue. The concentration gradient created in the perivascular spaces of the dermis speeds up the absorption of phenol. The risk of systemic toxicity can also increase. EMLA causes vasoconstriction followed by vasodilation. Vasodilation can sometimes be seen after only 30 minutes of EMLA under occlusion. How will these vasomotor changes affect the effectiveness or absorption of phenol - and therefore its toxicity ... 

The UV photons that have not been reflected or absorbed reach the basal layer of the epidermis, the papillary dermis and the reticular dermis. UVA rays that are emitted perpendicular to the skin penetrate deeply 66% get through the stratum corneum and 44% reach the basal layer. They have relatively little effect on the epidermis, but do severe damage to the dermis. Some 17% of UVB rays get through the stratum corneum and 3% reach the basal layer. They cause more damage to the epidermis than to the dermis. The thickness of the stratum corneum is therefore an important part of the skin s defenses, and treatments that damage it (dermabrasion, laser, AHA creams, peels, etc.) allow photons in and promote the free-radical damage described above. 

The basal pontine nuclei, the nucleus reticularis tegmenti pontis and the adjacent paramedian pontine reticular formation are connected with the cerebellum through the middle cerebellar peduncle. Both the nucleus reticularis tegmenti pontis and the paramedian pontine reticular formation send their fibers through the midline raphe into the pes pontis (fibrae rectae), where they deflect laterally to occupy the deep stratum of the middle cerebellar peduncle. 

Figure 1 Low-power (200X) micrograph of human adult skin showing the dermis (A) and epidermis (B). The nucleated basal keratinocytes define the beginning of the viable epidermis which is composed of five to six cell layers. As the basal keratinocytes migrate to the surface of the skin, they flatten and lose their nucleus until they resemble thin sheets. At this point, the keratinocytes are called comeocytes and this layer is called the stratum comeum (C). In this sample, the stratum comeum is partially detached due to tissue processing. However, note the onionskin-like appearance of the stratum comeum. Beneath the basal keratinocytes is the dermis (A). The dermis is composed of a pale-staining papillary (PD) layer and dense reticular (RD) layer. Note the prominent collagen bundles (arrows) within the reticular layer.

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