| Name: | thymus |
|---|---|
| Synonyms: | |
| Definition: | Paired organ where maturation of T-lymphocytes occurs. The adult thymus located on the dorsomedial aspect of the branchial cavity above the third pharyngeal cartilage. The thymus undergoes a period of rapid growth beginning at about the third week and continuing for several more weeks. Accompanying this growth is a dramatic change in the shape of the thymus. It is ovoid initially and then starts to grow dorsally along the skull, forming a characteristic protrusion. During this growth period the adult pattern of rag1-positive cortex and rag1-negative medulla becomes established. The protrusions diminish with age and the thymus gradually shrinks; at two years, the thymus is again confined to the pharynx with minimal if any protrusion. |
| Ontology: | Anatomy Ontology [ZFA:0001078] |
| Name: | lacks parts or has fewer parts of type |
|---|---|
| Synonyms: | loss of |
| Definition: | The bearer of this quality has_part < n of the indicated entity type, where n is the normal amount for a comparable organism. Note that the bearer of the quality is the whole, not the part. Formally: If a bearer entity e has fewer parts of type X at time t, then the number of instances x of X at t such that x part_of e is < n, where n is either the normal number for comparable entities, or n is stated explicitly. This case includes the limit case, where the bearer lacks all parts of the specified type. |
| Ontology: | Phenotypic Quality Ontology [PATO:0001999] |
| Name: | lymphocyte |
|---|---|
| Synonyms: | lymphocytes |
| Definition: | A cell of the B cell, T cell, or natural killer cell lineage. |
| Ontology: | Anatomy Ontology [ZFA:0009250] |