FB2026_03 , released September 17, 2026
CV Term Report
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General Information
Term testis ID (Ontology) FBbt:00004928 (Fly Anatomy)
Definition Tube of the male reproductive system connected to the seminal vesicle at the basal end. It is a tube 1.9mm long and 90-100 micrometers in diameter, with the basal half helically coiled and the distal half forming a freely extended arc. The coiled portion is spirally wound twice around a center occupied by the testicular duct and the distal portion of the seminal vesicle. The wall of the testis consists of two very thin layers containing widely spaced nuclei: an inner sheath and an outer sheath composed of small flattened polygonal cells that contain yellow pigment granules. The development of germline cells takes place in the testis.[ FlyBase:FBrf0007735 FlyBase:FBrf0033532 ]
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Data ClassFieldDirect annotations
Alleles (FBal)PHENOTYPE_MANIFEST_IN
Insertions (FBti)EXPRESSION_STAGE_TISSUE_POSITION
Insertions (FBti)PHENOTYPE_MANIFEST_IN
Constructs (FBtp)PHENOTYPE_MANIFEST_IN
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 Full annotation statements 
Relevant FlyBase reports
 Alleles Genes Images Insertions Constructs
 testis (all annotations which use CV term, excluding "NOT" statements)
     testis | adult stage
      --       --
     testis | adult stage | cell non-autonomous | somatic clone
      --       --
      --
     testis | adult stage | clone of cells
      --       --
      --
     testis | adult stage | germline clone
      --       --
      --
     testis | adult stage | progressive
      --       --       --
     testis | germline clone
      --       --
     testis | heat sensitive
      --       --
      --
     testis | larval stage
      --       --
      --
     testis | maternal effect
      --       --
      --
     testis | progressive
      --       --
      --
     testis | progressive | temperature conditional
      --       --       --       --
     testis | pupal stage
      --       --       --       --
     testis | RU486 conditional
      --       --       --
     testis | second instar larval stage
      --       --
      --
     testis | somatic clone
      --       --
     testis | somatic clone - tissue specific
      --       --
      --
     testis | temperature conditional
      --       --       --
     testis | third instar larval stage
      --       --
      --
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Vocabulary search 
organism
 |__adult____________________________
reproductive system                  |
 |__gonad____________________________|
 |__male reproductive system_________|
male organism                        |
 |__male-specific anatomical entity__|
male-specific anatomical entity      |
 |__male reproductive system_________|
multicellular structure              |
 |__gonad____________________________|
anatomical entity                    |
 |__male-specific anatomical entity__|
                                     testis  4920 rec.
                                      |__germinal proliferation center 737 rec.
                                      |   |__cyst progenitor cell 260 rec.
                                      |   |__germinal proliferation center hub(+) 244 rec.
                                      |   |__male germline stem cell 448 rec.
                                      |__male fusome 67 rec.
                                      |   |__spermatocyte fusome 28 rec.
                                      |__male germline cyst 2304 rec.
                                      |   |__cyst cell of testis(+) 235 rec.
                                      |   |__spermatid cyst(+) 1198 rec.
                                      |   |__spermatocyte cyst(+) 1007 rec.
                                      |   |__spermatogonial cyst(+) 419 rec.
                                      |__somatic cell of testis 728 rec.
                                      |   |__cyst cell of testis(+) 235 rec.
                                      |   |__cyst progenitor cell 260 rec.
                                      |   |__hub cell 211 rec.
                                      |   |__testis sheath epithelial cell(+) 122 rec.
                                      |   |__testis sheath muscle cell 33 rec.
                                      |__spermatozoon 1803 rec.
                                      |__testis sheath 174 rec.
                                      |   |__terminal epithelium of testis(+) 15 rec.
                                      |   |__testis sheath epithelial cell(+) 122 rec.
                                      |   |__testis sheath muscle cell 33 rec.
                                      |__waste bag 94 rec.
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Is a gonad
male-specific anatomical entity
Develops from larval testis
Part of adult
male reproductive system
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Synonyms
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UBERON:0000473