#52 MA:0001223 ! tympanic endothelium


In MA the tympanic membrane has two parts - the tympanic epithelium and endothelium

An endothelium is regarded (by GO and CL) as a subtype of epithelium. So naively we would expect a tympanic endothelium to be a subtype of the tympanic epithelium, which it is not.

Of course, this is too naive - MA:0001223 probably refers to something else, but it's not clear what.

Searches for "tympanic endothelium" all lead to MA or things derived from MA. Looser searches reveal some older references that suggest the endothelium may be an inner layer between the two epithelia.

PMID:11237469 seems reasonably up to date, I can't vouch for it's accuracy but is has a nice simple description of the TM as "The tympanic membrane is formed by the apposition of two epithelia provided by the EAM and the middle ear cavity, with a fibrous layer between them to give the membrane consistency and elasticity".

Could the MA term refer to this inner layer?

For what it's worth:

FMA has 3 layers of the tympanic membrane

........is_a FMA:56732 ! Layer of tympanic membrane *** [SYNONYM: "Tympanic membrane layer" (exact)]
.........is_a FMA:56735 ! Fibrocartilaginous ring of tympanic membrane [SYNONYM: "Anulus fibrocartilagineus (Membrana tympanica)" (exact)] [SYNONYM: "Fibrocartilaginous anulus of tympanic membrane" (exact)]
.........is_a FMA:56819 ! Cuticular layer of tympanic membrane [SYNONYM: "Cuticular stratum of tympanic membrane" (exact)] [SYNONYM: "Outer cuticular layer of tympanic membrane" (exact)] [SYNONYM: "Outer epithelial layer of tympanic membrane" (exact)]
.........is_a FMA:56830 ! Fibrous layer of tympanic membrane [SYNONYM: "Connective tissue layer of tympanic membrane" (exact)] [SYNONYM: "Fibrous stratum of tympanic membrane" (exact)] [SYNONYM: "Intermediate fibrous layer of tympanic membrane" (exact)]

Which corresponds roughly to the description in Gray's:

Structure.—The tympanic membrane is composed of three strata: a lateral (cutaneous), an intermediate (fibrous), and a medial (mucous). The cutaneous stratum is derived from the integument lining the meatus. The fibrous stratum consists of two layers: a radiate stratum, the fibers of which diverge from the manubrium of the malleus, and a circular stratum, the fibers of which are plentiful around the circumference but sparse and scattered near the center of the membrane. Branched or dendritic fibers, as pointed out by Grüber, are also present especially in the posterior half of the membrane
and 3 zones:

........is_a FMA:56720 ! Zone of tympanic membrane *** [SYNONYM: "Tympanic membrane zone" (exact)]
.........is_a FMA:56721 ! Pars flaccida of tympanic membrane [SYNONYM: "Pars flaccida (Membrana tympanica)" (exact)] [SYNONYM: "Shrapnell's membrane" (exact)]
.........is_a FMA:56722 ! Pars tensa of tympanic membrane [SYNONYM: "Pars tensa (Membrana tympanica)" (exact)]
.........is_a FMA:56723 ! Umbo of tympanic membrane [SYNONYM: "Tympanic membrane umbo" (exact)]


  • Terry Hayamizu

    Terry Hayamizu - 2012-01-03
    • assigned_to: nobody --> hayamizu
  • Terry Hayamizu

    Terry Hayamizu - 2012-09-18

    Not sure exactly what is going on here but, preliminarily, it appears that it may have something to do with the "secondary tympanic membrane" (see attached file). I will investigate further, and revise the ontology accordingly.

  • Terry Hayamizu

    Terry Hayamizu - 2012-09-18
    • status: open --> pending-accepted

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