FB2025_05 , released December 11, 2025
FB2025_05 , released December 11, 2025
CV Term Report
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General Information
Term photoreceptor cell R4 ID (Ontology) FBbt:00004219 (Fly Anatomy)
Definition Outer photoreceptor cell of the adult eye whose rhabdomere is located in the middle of the longer of the two non-parallel sides of trapezoid of rhabdomeres in each ommatidium, in between the rhabdomeres of R3 and R5. 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 R4" ; "R4"
Comment The name photoreceptor cell R4 is occasionally, mistakenly assumed to refer to any Rh4 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 R4 (presynaptic/postsynaptic) in a single lamina cartridge with each cell type was the following: L1 (38/-), L2 (41/-), L3 (8/-), L4 (-/1), Lai (37/2), T1 (2/-) and epithelial glia (9/-) (Rivera-Alba et al., 2011).
Links to External Ontologies
VFB:FBbt_00004219
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     164
Insertions (FBti)  EXPRESSION_STAGE_TISSUE_POSITION      34
Insertions (FBti)  PHENOTYPE_MANIFEST_IN      26
Constructs (FBtp)  PHENOTYPE_MANIFEST_IN      52
show Full annotation statements including this term (annotations to child terms are NOT included), and relevant FlyBase records
 Full annotation statements 
Relevant FlyBase reports
 Alleles Genes Insertions Constructs
 photoreceptor cell R4 (all annotations which use CV term, excluding "NOT" statements)     171     22     58     59
     photoreceptor cell R4 | cell autonomous | somatic clone       1       --       --       --
     photoreceptor cell R4 | cell non-autonomous | somatic clone       3       --       --       1
     photoreceptor cell R4 | cell non-autonomous | third instar larval stage       3       --       --       2
     photoreceptor cell R4 | ectopic       8       --       1      4
     photoreceptor cell R4 | ectopic | precursor       1       --       1       --
     photoreceptor cell R4 | ectopic | somatic clone       5       --       2       --
     photoreceptor cell R4 | heat sensitive       1       --       --       --
     photoreceptor cell R4 | increased number       2       --       --       --
     photoreceptor cell R4 | larval stage | somatic clone       3       --       1       --
     photoreceptor cell R4 | precursor | somatic clone       4       --       1       --
     photoreceptor cell R4 | pupal stage       1       --       1       --
     photoreceptor cell R4 | pupal stage | somatic clone       3       --       --       --
     photoreceptor cell R4 | somatic clone      28       --       7      5
     photoreceptor cell R4 | somatic clone | increased number       3       --       --       --
     photoreceptor cell R4 | somatic clone | third instar larval stage       2       --       --       --
     photoreceptor cell R4 | third instar larval stage       3       --       1       --
Spanning Tree (Parents/Children)
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  eye photoreceptor cell
   |__outer photoreceptor cell
       |__photoreceptor cell R4  355 rec.
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Is a outer photoreceptor cell
Develops from photoreceptor R4 precursor cell
Part of
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Synonyms
  • "lamina receptor cell R4" EXACT
    "R4" EXACT VFB_SYMBOL[ FlyBase:FBrf0247762 ]
    "receptor cell R4" RELATED
Secondary IDs
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CL:0000697
VFB:FBbt_00004219