flattened cells that overlie a base layer composed of columnar cells is the tissue that is the uppermost layer of the skin.
flattened cells that overlie a base layer composed of columnar cells is the tissue that is the uppermost layer of the skin.
what tissue is the uppermost layer of the skin?
flattened cells that overlie a base layer composed of columnar cells
the structure of the skin of the patagia and accessory areas for the patagia of a ptychozoon kuhli, flying gecko, exhibiting the passive gliding mechanism consists of five layers; a layer of adipose tissue is surrounded by a layer of dermis on each side (ventral and dorsal) and a layer of epidermis is external to the two dermal layers. the distribution of the adipose tissue is thickest close to the body wall. this thick layer of adipose tissue at close to the body wall is believed to provide a "safety factor" for the structural elements of the skin ( i.e. collagen fibers) near the body wall. the thick layer of adipose tissue is more compliant than the structural elements of the body wall (i.e. ribs, muscles), therefore will more readily deform(absorb force) before the structural elements of the skin experience a force. the layer of adipose tissue also aids in the creation of the domed and cambered shape of the patagia. with regards to the structure of the dermal layer of the patagia, there is a thick layer of collagen fibers oriented parallel to the axis of the patagial ribs. these collagen fibers act as the structural support for the shape of the patagia, and provide the stiffness necessary to resist shape chang . the most prominent features of the epidermal layer of the patagia are the scales. the morphology of the dorsal scales of the patagia change as a result of their functional role. a large portion of the dorsal scales of the patagia are arranged in regular rib-like pattern, which guide the flow of air and allow for the lizard to behave as an airfoil. however at the hinge joints (places where patagia folds and attaches to limbs), the regular rib like structure of scales breakdown into a more random distribution of scales. this breakdown of scales is believed to aid in the mechanical loading of the patagia during the unfurling process and also determining the extent the patagia unfurling during flight.
role of skin in locomotion
oceanic crust









































oceanic crust is the uppermost layer of the oceanic portion of a tectonic plate. it is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. the crust overlies the solidified and uppermost layer of the mantle. the crust and the solid mantle layer together constitute oceanic lithosphere.
oceanic crust