This article needs to be updated. The reason given is: no files for 2006 are listed at the cited source, but files for 2013 are there; NLM releases this information annually. Please help update this article to reflect recent events or newly available information. (February 2020)

The following is a partial list of the "A" codes for Medical Subject Headings (MeSH), as defined by the United States National Library of Medicine (NLM).

This list continues the information at List of MeSH codes (A12). Codes following these are found at List of MeSH codes (A14). For other MeSH codes, see List of MeSH codes.

The source for this content is the set of 2006 MeSH Trees from the NLM.

MeSH  A13 – animal structures

MeSH  A13.048 – air sacs

MeSH  A13.073 – anal sacs

MeSH  A13.114 – beak

MeSH  A13.163 – bursa of fabricius

MeSH  A13.223 – cloaca

MeSH  A13.242 – comb and wattles

MeSH  A13.250 – corpora allata

MeSH  A13.265 – crop, avian

MeSH  A13.316 – egg shell

MeSH  A13.332 – electric organ

MeSH  A13.350 – embryo, nonmammalian

• MeSH  A13.350.150 – chick embryo
• MeSH  A13.350.575 – chorioallantoic membrane

MeSH  A13.365 – fat body

MeSH  A13.370 – feathers

MeSH  A13.395 – forelimb

• MeSH  A13.395.248 – carpus, animal
• MeSH  A13.395.823 – wing

MeSH  A13.408 – ganglia, invertebrate

MeSH  A13.421 – gills

MeSH  A13.445 – harderian gland

MeSH  A13.453 – hemolymph

MeSH  A13.463 – hepatopancreas

MeSH  A13.473 – hindlimb

• MeSH  A13.473.683 – stifle
• MeSH  A13.473.821 – tarsus, animal

MeSH  A13.491 – hoof and claw

MeSH  A13.507 – horns

• MeSH  A13.507.288 – antlers

MeSH  A13.530 – interrenal gland

MeSH  A13.574 – malpighian tubules

MeSH  A13.589 – mammary glands, animal

MeSH  A13.600 – metrical gland

MeSH  A13.641 – mushroom bodies

MeSH  A13.660 – nictitating membrane

MeSH  A13.686 – optic lobe

MeSH  A13.706 – oviducts

• MeSH  A13.706.500 – fallopian tubes

MeSH  A13.734 – perianal glands

MeSH  A13.750 – photoreceptors, invertebrate

MeSH  A13.811 – salt gland

MeSH  A13.820 – scent glands

MeSH  A13.853 – stomach, avian

• MeSH  A13.853.363 – gizzard
• MeSH  A13.853.710 – proventriculus

MeSH  A13.869 – stomach, ruminant

• MeSH  A13.869.106 – abomasum
• MeSH  A13.869.524 – omasum
• MeSH  A13.869.697 – reticulum
• MeSH  A13.869.804 – rumen

MeSH  A13.895 – tail

MeSH  A13.939 – ultimobranchial body

MeSH  A13.950 – vibrissae

MeSH  A13.970 – wool

The list continues at List of MeSH codes (A14).