FB2026_03 , released September 17, 2026
FB2026_03 , released September 17, 2026
CV Term Report
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General Information
Term photoreceptor cell R2 ID (Ontology) FBbt:00004215 (Fly Anatomy)
Definition Outer photoreceptor cell of the adult eye whose rhabdomere is located in the middle of the longer of the two parallel sides of the trapezoid of rhabdomeres in each ommatidium. It has a single axon that projects along a single lamina optic cartridge (Fischbach and Dittrich, 1989; Wolff and Ready, 1993).[ FlyBase:FBrf0049410 FlyBase:FBrf0064798 FlyBase:FBrf0216925 ]
Also Known As "lamina receptor cell R2" ; "R2"
Comment The name photoreceptor cell R2 is occasionally, mistakenly assumed to refer to any Rh2 expressing photoreceptor cell. This is incorrect. This term only refers to a type of adult eye photoreceptor cell. The name is based simply on the position of the cell and its rhabdomere within each ommatidium - see figure 4 in Wolff and Ready, 1993. Cell connectivity was determined by analysis of semi-automated EM reconstruction of 749 serial sections of 21 complete lamina cartridges. The number of synaptic connections for R2 (presynaptic/postsynaptic) in a single lamina cartridge with each cell type was the following: L1 (43/-), L2 (45/1), L3 (10/-), L4 (-/1), Lai (39/-), T1 (2/-), Lawf (-/3), epithelial glia (13/-) and surface glia (1/-) (Rivera-Alba et al., 2011).
Links to External Ontologies
VFB:FBbt_00004215
Annotations
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Direct annotations: records annotated with this exact term (child terms are NOT included)
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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Relevant FlyBase reports
 Alleles Genes Insertions Constructs
 photoreceptor cell R2 (all annotations which use CV term, excluding "NOT" statements)
     photoreceptor cell R2 | cell non-autonomous | third instar larval stage
      --       --
     photoreceptor cell R2 | ectopic
      --
     photoreceptor cell R2 | heat sensitive
      --       --
     photoreceptor cell R2 | increased number
      --       --       --
     photoreceptor cell R2 | precursor
      --
      --
     photoreceptor cell R2 | somatic clone
      --
     photoreceptor cell R2 | somatic clone | increased number
      --       --       --
     photoreceptor cell R2 | somatic clone | third instar larval stage
      --       --       --
     photoreceptor cell R2 | third instar larval stage
      --
      --
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  eye photoreceptor cell
   |__outer photoreceptor cell
       |__photoreceptor cell R2  246 rec.
           |__photoreceptor cell R2 pigment granule
           |__photoreceptor cell R2 stalk 1 rec.
           |__rhabdomere R2 59 rec.
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Is a outer photoreceptor cell
Develops from photoreceptor R2 precursor cell
Part of
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Synonyms
  • "lamina receptor cell R2" EXACT
    "R2" EXACT VFB_SYMBOL[ FlyBase:FBrf0247762 ]
    "receptor cell R2" RELATED
Secondary IDs
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CL:0000690
VFB:FBbt_00004215