<prompt> What constitutes malpighian layer of skin?Corneum lucidumCorneum spinosumSpinosum and basaleBasale granulosum  <response>: Ref. Rooks Textbook of Dermatology, Pg 35 Histology of skinBasal layer:Mitotically active, produces other keratinocytesContains low molecular weight keratinSeparated from dermis by continuous basal membrane; keratinocytes are attached to this membrane by hemidesmosomesAlso contains melanocytes Squamous layer stratum spinosum:Also called prickle or malpighian layerHas several layers of cells, larger than basal layer, which become flat and eosinophilic as they approach the surface due to an increase in keratin and reduction in ribosomesMay have clear vacuolated cytoplasmCells are attached to each other by fine spiny bridges with central dot-like desmosomes Bizzozeros noduleLoss of spiny bridges causes acantholysis Granular layer stratum granulosum:1 - 3 layers of flattened cells with intensely basophilic keratohyaline granules, which contain precursors of filaggrin protein, which causes aggregation of keratin filamentsMalphigian layer includes spinosum and granulosum Stratum lucidum:Present only in soles and palms, between granular and cornified layerHomogenous eosinophilic zone Cornified layer stratum corneum:Also called horny layerBasket weave pattern of multiple layers of polyhedral cells without nucleiRegion is thicker and more compact in acral region peripheral body-limbs, fingers, ears Rete ridges:Undulating forms of epidermis and dermal papillae at dermoepidermal junction - flattens with aging 