A small outgrowth of the pharyngeal epithelium that is the site of lymphocyte cell production[ZFA]. [PMID]. [ ZFA:0001077 ]
Synonyms: thymic rudiment thymic primordium
Term information
- EFO:0003622
- EHDAA2:0002023
- TAO:0001077
- EMAPA:17523
- EHDAA:2969
- ZFA:0001077
efo_slim, vertebrate_core
we follow Kardong table 13.1 in having some developmental contribution of pouch 4 in mammals, but this isn't reflected in EHDAA2. Consider adding distinct term for mesenchyme (see EHDAA2), to indicate NC constribution.
A small outgrowth of the pharyngeal epithelium that is the site of lymphocyte cell production. Willett et al, 1999.[TAO]
variability of developmental origin: In fish, thymic primordia are generated by all the pouches except the first. However, in avians the thymus arises from pouches 3 and 4, whereas in humans it is only generated by the third pouch[PMID:16313389] The thymus arises from the second pouch in frogs, 2-6 in cartilaginous fish, 2-3 in reptiles, 3 or 4 in bony fish, birds and mammals. The final number is variable - 5 paired organs in sharks, 4 in caecilians, 3 in urodeles, 1 in many teleost, anurans and many mammals
Term relations
- primordium
- pharyngeal epithelium
- part of some pharyngeal gland
- part of some immune system
- has developmental contribution from some vagal neural crest