Editing Gallbladder (section)

===Microanatomy===
[[File:Gallbladder - intermed mag.jpg|thumb|[[Micrograph]] of a normal gallbladder wall. [[H&E stain]].]]
The gallbladder wall is composed of a number of layers. The innermost surface of the gallbladder wall is lined by a single layer of [[columnar epithelia|columnar cells]] with a [[brush border]] of [[microvilli]], very similar to intestinal absorptive cells.{{sfn|Gray's Anatomy|2008|p=1187-81}} Underneath the epithelium is an underlying [[lamina propria]], a [[muscular layer]], an outer perimuscular layer and [[serosa]]. Unlike elsewhere in the intestinal tract, the gallbladder does not have a [[muscularis mucosae]], and the muscular fibres are not arranged in distinct layers.<ref name=WHEATERS>{{cite book| first2=Philip J. | last2=Deakin (drawings) | first1=Barbara | last1=Young | title=Wheater's functional histology: a text and colour atlas | url=https://archive.org/details/wheatersfunction00youn | url-access=limited | year=2006 | publisher=Churchill Livingstone/Elsevier | location=[Edinburgh?] | isbn=978-0-443-06850-8 | edition=5th | page=[https://archive.org/details/wheatersfunction00youn/page/n671 298] | display-authors=1}}</ref>

The [[mucous membrane|mucosa]], the inner portion of the gallbladder wall, consists of a [[epithelium|lining]] of a [[Simple columnar epithelium|single layer of columnar]] cells, with cells possessing small hair-like attachments called [[microvilli]].{{sfn|Gray's Anatomy|2008|p=1187-81}} This sits on a thin layer of connective tissue, the [[lamina propria]].<ref name=WHEATERS /> The mucosa is curved and collected into tiny outpouchings called ''rugae''.{{sfn|Gray's Anatomy|2008|p=1187-81}}

A muscular layer sits beneath the mucosa. This is formed by [[smooth muscle]], with fibres that lie in longitudinal, oblique and transverse directions, and are not arranged in separate layers. The muscle fibres here contract to expel bile from the gallbladder.<ref name=WHEATERS /> A distinctive feature of the gallbladder is the presence of ''Rokitansky–Aschoff sinuses'', deep outpouchings of the mucosa that can extend through the muscular layer, and which indicate [[adenomyomatosis]].<ref name="ross">{{cite book|title=Histology: A Text and Atlas|url=https://archive.org/details/histologytextatl00ross_530|url-access=limited|publisher=Lippincott Williams & Wilkins|last1=Ross|first1=M.|last2=Pawlina|first2=W.|year=2011|isbn=978-0-7817-7200-6|page=[https://archive.org/details/histologytextatl00ross_530/page/n665 646]|edition=6th}}</ref> The muscular layer is surrounded by a layer of connective and [[adipose tissue|fat]] tissue.{{sfn|Gray's Anatomy|2008|p=1187-81}}

The outer layer of the fundus of gallbladder, and the surfaces not in contact with the liver, are covered by a thick [[serosa]], which is exposed to the [[peritoneum]].{{sfn|Gray's Anatomy|2008|p=1187-81}} The serosa contains blood vessels and lymphatics.<ref name=WHEATERS /> The surfaces in contact with the liver are covered in [[connective tissue]].{{sfn|Gray's Anatomy|2008|p=1187-81}}