FB2025_05 , released December 11, 2025
FB2025_05 , released December 11, 2025
CV Term Report
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General Information
Term labellum ID (Ontology) FBbt:00004531 (Fly Anatomy)
Definition The broadened, cushion-like, most distal part of the proboscis. It consists of two regions; its lateral surface has a hemispherical, on which there are approximately 33-34 gustatory (chemosensory) and two mechanosensory bristles. The gustatory bristles are arranged into three ill-defined rows of 10-11 bristles: two medial and one located peripherally. The mechanosensory bristles are located in the most dorsolateral area of the labella surface and are shorter than the gustatory sensilla. The inner (medial) surface bears a series of open collecting channels, the pseudotrachea, that converge medially and conduct food to the tip of the labrum. Taste pegs are present in between the pseudotrachea, with 30-40 on each side.[ FlyBase:FBrf0007734 FlyBase:FBrf0074012 FlyBase:FBrf0137194 FlyBase:FBrf0166419 FlyBase:FBrf0211916 FlyBase:FBrf0246028 ]
Also Known As "labella" ; "labial palpus" ; "labium"
Comment There is significant sexual dimorphism on the size of the labellum, with the male labellum being bigger than the female, in the anterior-posterior axis (Shanbag et al., 2001).
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Annotations
Records annotated with this term OR any of its CHILD TERMS
Records annotated with this exact term (annotations to child terms are NOT included)
Data Class Field Records
Alleles (FBal)  PHENOTYPE_MANIFEST_IN      77
Insertions (FBti)  EXPRESSION_STAGE_TISSUE_POSITION      10
Constructs (FBtp)  PHENOTYPE_MANIFEST_IN      17
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 Full annotation statements 
Relevant FlyBase reports
 Alleles Genes Images Insertions Constructs
 labellum (all annotations which use CV term, excluding "NOT" statements)      77     17     14     10     30
     labellum | cell autonomous | somatic clone       1       --       --       --       --
     labellum | conditional       7       --       --       --       7
     labellum | distal       3       --       --       --       --
     labellum | larval stage       1       --       --       --       1
     labellum | lateral       2       --       --       --       --
     labellum | somatic clone       4       --       --       --       1
Spanning Tree (Parents/Children)
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ectodermal derivative
 |__ventral ectoderm derivative___
anatomical entity                 |
 |__integumentary specialization__|
                                  labellum  404 rec.
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Is a integumentary specialization
ventral ectoderm derivative
Develops from labial disc
Part of adult labial segment
distiproboscis
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