FB2026_02 , released June 18, 2026
FB2026_02 , released June 18, 2026
CV Term Report
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General Information
Term FBbt:00001668 ID (Ontology) FBbt:00001668 (Fly Anatomy)
Definition Hematopoietic organ of the larva, located along the dorsal vessel, behind the brain. It produces the plasmatocytes, crystal cells and lamellocytes which are released at the end of the larval instar and onset of metamorphosis. It is composed of 3 pairs of bilateral lobes: an anterior primary lobe, a posterior secondary lobe and the most posterior lobe (or multiple lobes), the tertiary lobe. Each lobe is separated by pericardial cells. In the late embryo, the lymph gland consists of a single pair of lobes (primary lobes) containing around 20 cells each that flank the dorsal vessel. By the second larval instar, the lymph gland is composed of two or three new pairs of posterior lobes, and the primary lobes have increased in size to contain around 200 cells. During the first and early second larval instars, the lymph gland comprises only the hematopoietic progenitor population. The lymph gland increases in size ten-fold by the late third instar, and at this stage the progenitor cells (prohemocytes) become restricted to the medial region (medullary zone) of the primary lobe and become quiescent. The differentiated hemocytes are found in the periphery (cortical zone) of the primary lobe and these cells proliferate extensively. The posterior signaling center is a group of about 30 cells at the posterior tip of the primary lobe that secretes several signaling molecules and functions as a stem-cell niche. The secondary and tertiary lobes contain prohemocytes, and rarely a differentiated cell. Lymph glands are eliminated at metamorphosis.[ FlyBase:FBrf0031001 FlyBase:FBrf0032406 FlyBase:FBrf0074444 FlyBase:FBrf0155787 FlyBase:FBrf0162082 FlyBase:FBrf0187467 ]
Also Known As "embryonic/larval hematopoietic organ"
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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     199
Insertions (FBti)  EXPRESSION_STAGE_TISSUE_POSITION      90
Insertions (FBti)  PHENOTYPE_MANIFEST_IN      44
Constructs (FBtp)  PHENOTYPE_MANIFEST_IN      85
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
 FBbt:00001668 (all annotations which use CV term, excluding "NOT" statements)     201    152    134     97
     FBbt:00001668 | FBcv:0000154 | FBcv:0000336 | FBdv:00005339       3       --       1      2
     FBbt:00001668 | FBcv:0000336       1       --       --       --
     FBbt:00001668 | FBdv:00005289       2       --       --       --
     FBbt:00001668 | FBdv:00005336      35       --       1     21
     FBbt:00001668 | FBdv:00005336 | FBcv:0000309       3       --       --       1
     FBbt:00001668 | FBdv:00005336 | FBcv:0000311       3       --       --       4
     FBbt:00001668 | FBdv:00005337       2       --       --       2
     FBbt:00001668 | FBdv:00005338       6       --       1      2
     FBbt:00001668 | FBdv:00005339      19       --       --      10
Spanning Tree (Parents/Children)
Only view relationship: 
FBbt:00001727
 |__FBbt:00001664__
FBbt:00005057      |
 |__FBbt:00001664__|
FBbt:00025998      |
 |__FBbt:00026000__|
FBbt:00100313      |
 |__FBbt:00007010__|
                   FBbt:00001668  753 rec.
                    |__FBbt:00001669 227 rec.
                    |   |__FBbt:00052152(+)
                    |   |__FBbt:00100310(+) 58 rec.
                    |   |__FBbt:00100311(+) 72 rec.
                    |   |__FBbt:00100312 32 rec.
                    |__FBbt:00001670 67 rec.
                    |__FBbt:00001671 32 rec.
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Is a multi-tissue structure
trunk mesoderm derivative
Develops from lymph gland primordium
Part of larval circulatory system
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Synonyms
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UBERON:6001668