FB2026_03 , released September 17, 2026

CV Term Report

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General Information

Term

Y chromosome loop

ID (Ontology)

FBbt:00004940 (Fly Anatomy)

Definition

Loop in the Y chromosome in the nucleus of primary spermatocytes. Y loops are caused by the transcription of male fertility factors present on the Y chromosome.[ FlyBase:FBrf0064778 ]

Comment

Links to External Ontologies

Annotations

Records annotated with this term OR any of its CHILD TERMS

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Direct annotations: records annotated with this exact term (child terms are NOT included)

Data Class	Field	Direct annotations
Alleles (FBal)	PHENOTYPE_MANIFEST_IN
Insertions (FBti)	EXPRESSION_STAGE_TISSUE_POSITION
Insertions (FBti)	PHENOTYPE_MANIFEST_IN

Full annotation statements including this term (annotations to child terms are NOT included), and relevant FlyBase records

Full annotation statements	Relevant FlyBase reports
Full annotation statements	Alleles	Genes	Insertions
Y chromosome loop (all annotations which use CV term, excluding "NOT" statements)

Spanning Tree (Parents/Children)

spermatocyte cyst
 |__spermatocyte_____________________
anatomical structure                 |
 |__cell component___________________|
male organism                        |
 |__male-specific anatomical entity__|
male germline cell                   |
 |__spermatocyte_____________________|
anatomical entity                    |
 |__male-specific anatomical entity__|
                                     Y chromosome loop  156 rec.

Spanning Tree View Settings
Parents/Children View Depth	Show hierarchy levels: for parents, for children
Relationships
Is a	cell component male-specific anatomical entity
Part of	spermatocyte
Synonyms & Secondary IDs
Synonyms

Secondary IDs

External Crossreferences & Linkouts