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Granule budget twin

myelocyte, alive: the cell keeps working while you watch. Every motion runs at a rate from a source, and the panel below drives it.

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Control panel

One myelocyte as geometry: the cytoplasm is the space the Golgi must fill with granules, and the nucleus takes what is left.

Cytoplasmic volume

1,385 um3

381 to 2,786 um3 across the sourced ranges. No sourced capacity for this quantity, so the bar places this cell between the smallest and the largest the sourced ranges allow.

The myelocyte's whole job is to fill this space with secondary granules while the primary granules made in the stage before sit in it already. Cell size and nucleus size are both measured; the cytoplasm is what the two leave between them, and it is the budget every granule has to come out of.

source 1

20 um acrossOne cell at a fixed scale; the circle grows and shrinks with the slider.

Inputs

12 to 18 um · human, normal bone marrow and blood · histochemical staining, electron microscopy and cytochemistry · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

myelocyte diameter 12 to 18 um across the stage; the cell is largest early and smaller after each division

8 to 10 um · human, normal bone marrow · electron microscopy · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

round nucleus 8 to 10 um with chromatin condensing at the periphery and no visible nucleolus, which is what separates the myelocyte from its parent the promyelocyte

0.4 to 0.5 um · human, normal bone marrow · electron microscopy with peroxidase cytochemistry · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

azurophils are the large granule type, spherical or ellipsoid, produced only in the promyelocyte stage; by the myelocyte stage no new ones are made

0.2 to 0.35 um · human, normal bone marrow · electron microscopy with peroxidase cytochemistry · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

specifics are the smaller granule type, spherical or elongated, formed during the myelocyte stage; Bainton gives them as smaller than the azurophils without a single fixed diameter, so the slider spans the described size class

0 to 5 cells · human, normal bone marrow · electron microscopy · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

Count is illustrative; the myeloid island contains promyelocytes alongside myelocytes. Range 0-5 is owner-controllable. No per-island cell count is stated in the abstract.

0 to 5 cells · human, normal bone marrow · electron microscopy · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

Count is illustrative; the myeloid island contains metamyelocytes alongside myelocytes. Range 0-5 is owner-controllable. No per-island cell count is stated in the abstract.

0 to 4 cells · human, normal bone marrow · electron microscopy · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

Count is illustrative; reticular stromal cells form the scaffold of the myeloid island. Range 0-4 is owner-controllable.

50 to 300 granules · human, normal bone marrow · electron microscopy with peroxidase cytochemistry · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

Illustrative range: Bainton 1971 states azurophils are inherited from the promyelocyte and come to be outnumbered roughly 2:1 by secondary granules by the end of the myelocyte stage; a default of 200 is illustrative. No per-cell count is stated in the abstract. Range is owner-controllable; the slider is listed as no-rate (the process is declared animates: false).

10 to 400 granules · human, normal bone marrow · electron microscopy with peroxidase cytochemistry · Bainton DF, Ullyot JL, Farquhar MG 1971, J Exp Med · source

Illustrative range: Bainton 1971 states secondary granules come to outnumber primary granules approximately 2:1 by the end of the myelocyte stage (roughly 400 vs 200). Default 200 represents a mid-stage myelocyte. No per-cell count is stated in the abstract. Range is owner-controllable; the slider is listed as no-rate (the process is declared animates: false).

Readouts

Whole cell volume
1,767 um3
905 to 3,054 um3 propagated
human · sphere volume on the measured diameter range  · source 1
Interval from evaluating at the ends of each input range; assumes the formula moves one way in each input.
Nucleus volume
382 um3
268 to 524 um3 propagated
human · sphere volume on the measured diameter range  · source 1
Interval from evaluating at the ends of each input range; assumes the formula moves one way in each input.
Nucleus over cytoplasm, by volume
0.276
0.096 to 1.37 propagated
human · volume ratio from the two measured diameters. The N:C ratio a haematologist reports is read as an area on a stained smear, not a volume, so this number is not the bench figure and should not be compared with it  · source 1
Interval from evaluating at the ends of each input range; assumes the formula moves one way in each input.
One primary granule
0.048 um3
0.034 to 0.065 um3 propagated
human · sphere volume on the electron microscopy size class  · source 1
Interval from evaluating at the ends of each input range; assumes the formula moves one way in each input.
One secondary granule
0.014 um3
0.004 to 0.022 um3 propagated
human · sphere volume on the electron microscopy size class  · source 1
Interval from evaluating at the ends of each input range; assumes the formula moves one way in each input.
Primary over secondary, by volume
3.38 fold
1.49 to 15.6 fold propagated
human · cube of the diameter ratio. This is why the switch matters: a secondary granule costs the cell several times less membrane and cargo than a primary one, and the myelocyte makes them in far greater number  · source 1
Interval from evaluating at the ends of each input range; assumes the formula moves one way in each input.
Secondary granules the cytoplasm could hold
98,000
16,980 to 665,000 propagated
human · a geometric ceiling only: cytoplasmic volume divided by one granule volume, with no packing efficiency, no organelles and no cytosol subtracted. The real cell holds far fewer. It is here to bound the problem, not to count granules  · source 1
Interval from evaluating at the ends of each input range; assumes the formula moves one way in each input.

Withheld

Fraction of cytoplasm occupied by granules
No sourced value for this yet: it needs the two granule counts, and neither is sourced, so the fraction cannot be computed without inventing them.
Divisions the myelocyte undergoes
Disputed and unsourced as a number: the textbook places the myelocyte as the last mitotic stage, and a 2026 in situ labeling study revises the trajectory (https://pubmed.ncbi.nlm.nih.gov/42485667/). No verified abstract gives a division count, so none is shown.
Circulating neutrophil lifespan (days)
Three sourced entries, each a different kind of quantity. (1) Pillay 2010 (Blood, PMID 20410504, heavy-water 2H2O in vivo labeling): average 5.4 days. (2) van Grinsven 2026 (Blood, PMID 42485667, in situ precursor labeling): lower bound, at least 6 days -- the abstract says 'at least'; the title says '6-day' flat, which understates it. A lower bound of 6 does not contradict an average of 5.4 the way two point values would. (3) Tak 2013 (Blood, PMID 23625199): a methodological challenge to the heavy-water method behind the 5.4-day figure. The field disputes the method, not just the number. Shown as argued about rather than silently reconciled. The myelocyte twin does not derive a lifespan from its geometry; these sit in sources and withheld for honest context only.

Sources

Bainton DF, Ullyot JL, Farquhar MG. The development of neutrophilic polymorphonuclear leukocytes in human bone marrow. J Exp Med 1971
human, normal bone marrow and blood · histochemical staining, electron microscopy and cytochemistry
Dancey JT, Deubelbeiss KA, Harker LA, Finch CA. Neutrophil kinetics in man. J Clin Invest 1976
human, 13 normal subjects · marrow sections with 3H-thymidine autoradiography
Cowland JB, Borregaard N. Granulopoiesis and granules of human neutrophils. Immunol Rev 2016
human, review · review
van Grinsven E et al. Human precursor labeling in situ reveals a conveyor belt differentiation trajectory and a 6-day neutrophil life span. Blood 2026
human · in situ precursor labeling. Newer and more direct method than heavy-water labeling; reports 6-day neutrophil lifespan. A second sourced value of 5.4 days from Pillay 2010 (Blood, heavy-water labeling) measures the same quantity by a different method; both are correct given their methods and neither averages the other.
Pillay J et al. In vivo labeling with 2H2O reveals a human neutrophil lifespan of 5.4 days. Blood 2010
human · heavy-water (2H2O) in vivo labeling. Reports average 5.4-day lifespan. Method challenged by Tak 2013 (PMID 23625199). See withheld.neutrophil_lifespan_days.
Tak T et al. What's your age again? Determination of human neutrophil half-lives revisited. J Leukoc Biol 2013
human · methodological critique of heavy-water labeling used in Pillay 2010. Does not report a lifespan; disputes the method behind the 5.4-day figure. Listed here because the lifespan is shown as argued about, not settled.

Research use only. Every number here is geometry on published ranges, not a measurement of any individual.

Substances tested 8

Filgrastim (recombinant human methionyl G-CSF) recombinant granulocyte colony-stimulating factor
acts on G-CSF receptor (CSF3R) on the granulocytic series from myeloblast onward
In chemotherapy-induced febrile neutropenia, filgrastim reduced the median days of neutropenia from 4.0 to 3.0 (neutrophil count under 0.5 x 10^9/L, p = 0.005) and time to resolution of febrile neutropenia from 6.0 to 5.0 days (p = 0.01). Days of fever were unchanged at 3.0 in both arms. Risk of hospitalisation beyond 11 days was halved (relative risk 2.1, 95 percent CI 1.1 to 4.1, p = 0.02).
dose: 12 micrograms/kg body weight per day  · human, 218 patients with cancer and febrile neutropenia (109 filgrastim, 107 placebo)  · randomised double-blind placebo-controlled trial  · Maher DW et al. 1994, Ann Intern Med  · source
G-CSF (endogenous, gene knockout) endogenous haematopoietic cytokine
acts on G-CSF receptor (CSF3R)
Mice lacking G-CSF have chronic neutropenia with blood neutrophils at 20 to 30 percent of wild type, granulocyte and macrophage progenitor cell deficiency, and impaired neutrophil mobilisation. Marrow granulopoietic precursors, the pool that contains the myelocyte, fall by about 50 percent.
dose: genetic deletion, no dose  · mouse, G-CSF null  · gene knockout, blood and marrow counts, progenitor assays  · Lieschke GJ et al. 1994, Blood  · source
All-trans retinoic acid (ATRA, tretinoin) retinoid, differentiation agent
acts on retinoic acid receptor alpha; in acute promyelocytic leukemia the PML-RARalpha fusion that arrests maturation at the promyelocyte, the myelocyte's parent stage
All 24 patients with acute promyelocytic leukemia attained complete remission without marrow hypoplasia. In marrow suspension culture 14 of 15 tested patients showed morphological maturation in response to retinoic acid at 1 micromol/L; chloroacetate esterase and alpha-naphthyl acetate esterase staining and electron microscopy confirmed differentiation to granulocytes with functional maturation by nitroblue tetrazolium reduction. Side effects were mild dryness of lips and skin with occasional headache and digestive symptoms. Eight patients relapsed after 2 to 5 months.
dose: 45 to 100 mg/m2 per day in patients; 1 micromol/L in marrow suspension culture  · human, 24 patients with APL  · open-label treatment series with marrow suspension culture, cytochemistry and electron microscopy  · Huang ME et al. 1988, Blood  · source
Cytosine arabinoside (ara-C, cytarabine), low dose antimetabolite, pyrimidine nucleoside analogue
acts on DNA synthesis in dividing marrow precursors; the myelocyte is in the mitotic pool and is therefore a target
The single patient in the series who did not respond to retinoic acid in vitro and was resistant to retinoic acid treatment attained complete remission after low-dose cytosine arabinoside was added. Reported as a single case within the ATRA series.
dose: low dose, exact dose not stated in the abstract  · human, 1 patient with APL resistant to retinoic acid  · clinical observation within a treatment series  · Huang ME et al. 1988, Blood. THIN: single case within a 24-patient series  · source
CysLTR1 antagonists (clinically available leukotriene receptor blockers) cysteinyl leukotriene receptor 1 antagonist
acts on CysLTR1, induced downstream of STAT3 on tumour-promoting myeloid progenitors
Genetic ablation and pharmacological inhibition of CysLTR1 diminished tumour growth with enhanced antitumour immunity. The antitumour effect ran through transcriptomic rewiring of granulopoiesis and reprogramming of neutrophils toward an antitumour phenotype, requiring MXD1 and NFE2 to direct myeloid progenitor commitment and differentiation with controlled de novo synthesis of granule cargoes. Targeting CysLTR1 overcame resistance to anti-PD1 in multiple mouse tumour models.
dose: not stated in the abstract  · mouse tumour models  · genetic ablation and pharmacological inhibition, transcriptomics, checkpoint therapy combination  · Tang H et al. 2026, Nat Cancer  · source
Semaglutide GLP-1 receptor agonist
acts on no myelocyte target identified; the association is clinical, not mechanistic
Agranulocytosis requiring hospitalisation was attributed to semaglutide in a single patient and treated with granulocyte colony-stimulating factor. No mechanism at the level of the granulocytic precursor is established by this report.
dose: not stated in the abstract  · human, 1 patient  · case report  · Calvo Arbeloa M et al. 2026, Eur J Hosp Pharm. THIN: single case report, association only  · source
Macrocyclic peptide inhibitors of NSP4 (MCP-3, MCP-4) de novo macrocyclic peptide protease inhibitors
acts on neutrophil serine protease 4 (NSP4), stored in azurophilic (primary) granules and highly expressed in myeloid precursor cells
Six macrocyclic peptides from mRNA-displayed libraries strongly inhibited recombinant and endogenous cell-derived NSP4 and did not inhibit 13 structurally related proteases. Crystal structures of the two most potent inhibitors show binding at the NSP4 active site, with a substrate-like interaction and resistance to hydrolysis resembling the sunflower trypsin inhibitor-1. Research tools, not therapeutics.
dose: MCP-3 KD 6.5 nM; MCP-4 KD 1.0 nM  · human NSP4, recombinant and cell-derived  · mRNA display library screen, biochemical assays with activity-based probes, X-ray crystallography  · Tang W et al. 2026, J Mol Biol  · source
C/EBP epsilon (transcription factor, loss of function) endogenous transcription factor, not a drug
acts on CCAAT/enhancer binding protein epsilon locus
A five-basepair deletion in the second exon truncates the 32-kD major isoform with loss of the dimerisation domain, DNA binding region and transcriptional activity. The result is neutrophil-specific granule deficiency: recurrent pyogenic infections, defective chemotaxis and bactericidal activity, and absent secondary granule proteins. This establishes C/EBP epsilon as required for the promyelocyte to myelocyte transition. Listed here because it is the molecular switch any agent aiming at secondary granule formation would have to act through.
dose: genetic, no dose  · human patient with specific granule deficiency; knockout mouse for comparison  · genomic sequence analysis, functional assays on neutrophil progenitors  · Lekstrom-Himes JA et al. 1999, J Exp Med  · source

Every row rests on a PubMed abstract read in full on 2026-09-12. A dose the abstract does not state is written as such, never guessed. The myelocyte is a marrow precursor, so most agents here act on the granulocytic series as a whole rather than on the myelocyte in isolation; the row says which. Research reference, not medical advice.

Public datasets 5

GSE98946 non-coding RNA profiling by high throughput sequencing Homo sapiens
Gene expression of human bone marrow granulocytic differentiation stages
Schwarzer A et al. 2017, Nat Commun  · paper  · public at NCBI GEO; NCBI data are free to use with attribution, no licence text of its own  · accession resolved 2026-09-12 via eutils esummary
GSE294330 non-coding RNA profiling and expression profiling by high throughput sequencing Homo sapiens
A molecular atlas of human granulopoiesis
A molecular atlas of human granulopoiesis, Research Square preprint. THIN: the linked manuscript is a preprint, not peer reviewed  · paper  · public at NCBI GEO  · accession resolved 2026-09-12 via eutils esummary
GSE48305 expression profiling by high throughput sequencing Mus musculus; Homo sapiens
Orchestrated intron retention regulates normal granulocyte differentiation [RNA-Seq]
Wong JJ et al. 2013, Cell  · paper  · public at NCBI GEO  · accession resolved 2026-09-12 via eutils esummary
GSE137496 expression profiling by high throughput sequencing Homo sapiens
Defective SEC61α1 underlies a novel cause of autosomal dominant severe congenital neutropenia
Linked publication not returned by eutils elink on 2026-09-12; accession and title resolved, paper left empty rather than guessed  · public at NCBI GEO  · accession resolved 2026-09-12 via eutils esummary
GSE134922 expression profiling by high throughput sequencing Homo sapiens
Granulocytic nuclear lobation.
Linked publication not returned by eutils elink on 2026-09-12; accession and title resolved, paper left empty rather than guessed. The nuclear shape change this dataset addresses begins at the metamyelocyte, the myelocyte's child  · public at NCBI GEO  · accession resolved 2026-09-12 via eutils esummary

Public datasets that resolve the granulocytic maturation series, the myelocyte among its stages. Every accession was resolved through NCBI eutils esummary on the date shown and the title is the one the archive returns, not a paraphrase.