As seen with the electron microscope, the basement membrane is composed of two layers, the basal lamina and the reticular lamina. ... The underlying connective ...BasementmembraneFromWikipedia,thefreeencyclopediaJumptonavigationJumptosearchAthinfibrouslayerbetweenthecellsandtheadjacentconnectivetissueinanimalsBasementmembraneTheepitheliumandendobasementmembraneinrelationtoepitheliumandendothelium.AlsoseenareotherextracellularmatrixcomponentsImageshowingthebasementmembraneoftheliningofthemouth,whichseparatesthelining(epithelium)fromalooselayerofconnectivetissue(thelaminapropria)DetailsIdentifiersLatinmembranabasalisMeSHD001485THH2.00.00.0.00005FMA63872Anatomicaltermsofmicroanatomy[editonWikidata]Thebasementmembraneisathin,pliablesheet-liketypeofextracellularmatrix,thatprovidescellandtissuesupportandactsasaplatformforcomplexsignalling.[1][2]Thebasementmembranesitsbetweenepithelialtissuesincludingmesotheliumandendothelium,andtheunderlyingconnectivetissue.[3][4]Contents1Structure2Function3Clinicalsignificance4Seealso5References6FurtherreadingStructure[edit]Asseenwiththeelectronmicroscope,thebasementmembraneiscomposedoftwolayers,thebasallaminaandthereticularlamina.[4]TheunderlyingconnectivetissueattachestothebasallaminawithcollagenVIIanchoringfibrilsandfibrillinmicrofibrils.[5]Thebasallaminalayercanfurtherbesubdividedintotwolayersbasedontheirvisualappearanceinelectronmicroscopy.Thelighter-coloredlayerclosertotheepitheliumiscalledthelaminalucida,whilethedenser-coloredlayerclosertotheconnectivetissueiscalledthelaminadensa.Theelectron-denselaminadensalayerisabout30–70nanometersthickandconsistsofanunderlyingnetworkofreticularcollagenIVfibrilswhichaverage30nanometersindiameterand0.1–2micrometersinthicknessandarecoatedwiththeheparansulfate-richproteoglycanperlecan.[6]Inadditiontocollagen,thissupportivematrixcontainsintrinsicmacromolecularcomponents.Thelaminalucidalayerismadeupoflaminin,integrins,entactins,anddystroglycans.Integrinsareakeycomponentofhemidesmosomeswhichservetoan