Eosinophil Morphological Observation: Staining Basis, Identification Points, and Research Validation

Eosinophils are an important leukocyte type within the granulocytic lineage. They are mainly involved in the pathological processes of parasitic infection, allergic reactions, asthma, drug reactions, autoimmune inflammation, and certain hematologic diseases. Morphological observation can directly evaluate eosinophil number, maturation status, granule morphology, nuclear segmentation, and abnormal changes. It is an important component of peripheral blood smear examination, bone marrow smear analysis, body fluid cytology, and tissue infiltration assessment.

Keywords: eosinophils; morphological observation; blood smear; bone marrow smear; Romanowsky staining; Wright staining; Giemsa staining; eosinophilic granules; EPX; ECP; CCR3; IL-5

1、Basic Logic of Eosinophil Morphological Observation

1.1 Observation targets

(1) Mature eosinophils

Mature eosinophils are usually seen in peripheral blood smears and are slightly larger than mature neutrophils. Their typical features include a bilobed or segmented nucleus and cytoplasm filled with coarse, uniform, orange-red to brick-red specific granules. The cell boundary is relatively clear, and the cytoplasmic background is usually pale blue or pale pink.

(2) Immature eosinophils

Immature eosinophils are mainly observed in bone marrow smears, including eosinophilic myelocytes, metamyelocytes, and band forms. Identification requires combined evaluation of chromatin maturation, cytoplasmic volume, nuclear shape changes, and the degree of eosinophilic granule formation. In early stages, granules may not be fully typical, and distinction from the neutrophilic lineage and abnormal granular cells is required.

(3) Abnormal eosinophils

Abnormal eosinophils may show reduced granules, uneven granule size, abnormal granule staining, abnormal nuclear segmentation, vacuole formation, or abnormal cytoplasmic development. These changes may be seen in reactive eosinophilia, clonal eosinophilia, and some myeloid neoplasms.

1.2 Purposes of morphological observation

(1) Confirming cell type

The first purpose of eosinophil morphological observation is accurate identification during leukocyte differential counting. Typical eosinophilic granules are the most important morphological basis, but nuclear shape, cytoplasmic background, and overall smear staining quality should also be considered.

(2) Assessing maturation stage

In bone marrow samples, eosinophils may be present at different maturation stages. Nuclear chromatin, nuclear shape, granule formation, and cytoplasmic ratio can help determine whether eosinophil development is continuous, whether maturation is blocked, or whether abnormal proliferation is present.

(3) Suggesting pathological background

An increased eosinophil percentage alone cannot determine the cause. If morphological abnormalities, increased eosinophilic precursor cells in bone marrow, abnormal granules, or accompanying abnormalities in other blood cells are present, immunophenotyping, cytogenetic testing, or molecular testing should be considered.

Table 1 Core Elements in Eosinophil Morphological Observation

Observation item	Main content	Interpretive significance	Notes
Cell size	Whether slightly larger than neutrophils	Helps identify mature eosinophils	Affected by smear thickness and cell spreading
Nucleus	Bilobed, segmented, or band-shaped nucleus	Assesses maturation and nuclear abnormalities	Nuclear shape alone is insufficient for identification
Cytoplasmic granules	Orange-red, coarse, relatively uniform granules	Most important identification feature of eosinophils	Staining conditions may affect color intensity
Cytoplasmic background	Pale blue, pale pink, or light background	Helps distinguish maturation stage	Difficult to observe when granules are dense
Granule distribution	Uniform or abnormally concentrated	Assesses granule maturation and abnormalities	Staining precipitates must be excluded
Accompanying cellular changes	Neutrophils, basophils, blasts, etc.	Helps distinguish reactive or clonal background	Should be interpreted with the whole smear and count results

2、Staining Methods and Basis of Microscopic Observation

2.1 Romanowsky-type staining

(1) Wright staining

Wright staining is commonly used for eosinophil observation in peripheral blood smears and bone marrow smears. Eosinophilic granules usually appear orange-red or red, while nuclei appear bluish purple to purplish red. It is suitable for routine leukocyte differential counting and assessment of granulocyte maturation stages.

(2) Giemsa staining

Giemsa staining provides good visualization of nuclear chromatin and some parasite structures, and it can also be used for eosinophil observation. Granule color may differ slightly from that seen in Wright staining, so interpretation should follow the staining system and laboratory standards.

(3) Wright-Giemsa staining

Wright-Giemsa staining combines overall blood cell morphology with nuclear and cytoplasmic detail. It is suitable for bone marrow smears, peripheral blood review, and morphological analysis of hematologic diseases. Under this staining system, eosinophilic granules, nuclear segmentation, and cytoplasmic maturation are usually easy to observe.

2.2 HE staining and tissue sample observation

(1) Tissue infiltration observation

In tissue sections, eosinophils are commonly observed using HE staining. Their cytoplasmic granules usually appear strongly eosinophilic, red to orange-red, and can be used to assess eosinophilic infiltration in the skin, gastrointestinal tract, respiratory tract, nasal polyps, and other tissues.

(2) Association with tissue background

HE staining also allows simultaneous observation of tissue structure, inflammatory background, necrosis, fibrosis, and epithelial damage. Unlike blood smears, cells in tissue sections are affected by sectioning direction, and the bilobed nucleus may not always be fully visible. Granule morphology and tissue localization should therefore be considered together.

(3) Application boundaries

HE staining is suitable for tissue-level infiltration assessment but is less suitable than blood or bone marrow smears for detailed evaluation of granulocyte maturation stages. If eosinophil-associated proteins need to be confirmed, immunostaining for markers such as EPX and ECP can be performed.

2.3 Effects of staining conditions

(1) pH effect

Romanowsky-type staining is sensitive to buffer pH. When pH is too low, the smear may appear overly red, eosinophilic granules may appear excessively strong, and leukocyte nuclear staining may be pale. When pH is too high, the background becomes bluish, and red blood cell and cytoplasmic colors become abnormal, which may affect interpretation of eosinophilic granules.

(2) Staining time

Insufficient staining can make both granules and nuclei pale, resulting in unclear eosinophilic granules. Overstaining deepens the background and reduces contrast between nuclei and granules. Eosinophil morphology should be evaluated in areas with uniform staining and normal red blood cell background.

(3) Smear quality

If the smear is too thick, cell overlap and granule accumulation may cause misinterpretation. If the smear is too thin, cells may be distorted or insufficiently distributed. Mature eosinophils should be assessed in the monolayer region near the junction between the body and tail of the blood film.

Table 2 Common Staining Methods for Eosinophil Observation

Staining method	Granule display characteristics	Applicable samples	Main uses
Wright staining	Granules usually appear orange-red to red	Peripheral blood, bone marrow	Leukocyte differential count, granulocyte morphology
Giemsa staining	Clear nuclear staining, granules visible	Blood smears, bone marrow, parasite-related samples	Parasite background and nuclear-cytoplasmic structure observation
Wright-Giemsa staining	Balanced nuclear-cytoplasmic contrast and granule display	Peripheral blood, bone marrow	Comprehensive blood cell morphology analysis
May-Grünwald-Giemsa staining	Rich cellular layering	Bone marrow, cytology smears	Cytology and bone marrow morphology observation
Diff-Quik staining	Rapid staining, slightly limited detail	Cytology smears, rapid assessment samples	Screening and on-site morphological evaluation
HE staining	Eosinophilic granules appear red to orange-red	Tissue sections	Tissue infiltration, inflammatory background, and tissue structure observation

3、Morphological Features of Mature Eosinophils

3.1 Cell size and outline

(1) Cell size

Mature eosinophils are usually about 12–17 μm in diameter and are slightly larger than mature neutrophils. Cell size may be affected by smear spreading, so it cannot be used as the sole identification criterion.

(2) Cell outline

The cell outline is usually round and well defined. Poor smear preparation, prolonged sample storage, or cell damage may cause cytoplasmic granules to leak out, resulting in unclear cell boundaries or free granules.

(3) Cytoplasmic status

The cytoplasm is mostly occupied by coarse eosinophilic granules, and its background color is less obvious than that of lymphocyte cytoplasm. When granules are dense, the cytoplasmic ground color may be obscured, requiring interpretation based on nuclear shape and granule color.

3.2 Nuclear characteristics

(1) Typical bilobed nucleus

The most typical nuclear shape of a mature eosinophil is a bilobed nucleus, with the two lobes connected by a thin chromatin strand. The nuclear chromatin is mature, deeply stained, and relatively coarse.

(2) Segmented nucleus

Some mature eosinophils may have more than two nuclear lobes, but their segmentation is usually less complex than that of neutrophils. If excessive segmentation or obvious nuclear abnormalities are present, other cellular abnormalities should be considered when assessing pathological significance.

(3) Band-shaped or incompletely segmented nucleus

Band-shaped or incompletely segmented eosinophils may occasionally be seen in peripheral blood. If their proportion is clearly increased, increased bone marrow release, reactive proliferation, or a myeloid abnormality should be considered.

3.3 Cytoplasmic granule characteristics

(1) Color

Eosinophilic granules are usually orange-red, red, or brick-red and are the key feature for identifying mature eosinophils. Granule color is strongly influenced by the staining system and pH; smears that are globally too red or too blue are unsuitable for fine color interpretation.

(2) Size

Mature eosinophilic granules are coarser than neutrophil granules and are usually relatively uniform. Abnormally coarse, uneven, or clearly sparse granules should raise concern for abnormal eosinophils.

(3) Distribution

Normal mature eosinophilic granules are diffusely distributed in the cytoplasm and should not completely obscure the nucleus. Granule aggregation, degranulation, or obvious cytoplasmic vacuoles should be interpreted in relation to sample preservation, inflammatory status, and pathological background.

Table 3 Typical Morphology of Mature Eosinophils

Morphological item	Typical appearance	Interpretive value	Common confounding factors
Cell size	Slightly larger than neutrophils	Auxiliary identification	Differences in smear spreading
Nucleus	Bilobed nucleus common	Identifies mature eosinophils	Segmented neutrophil nuclei
Chromatin	Coarse and mature	Distinguishes immature stages	Pale nuclei due to insufficient staining
Cytoplasmic granules	Coarse, orange-red, relatively uniform	Main identification basis	Stain precipitates, granule leakage
Cytoplasmic background	Pale blue or pale pink	Auxiliary observation	Not obvious when granules are too dense
Cell boundary	Relatively clear	Assesses cellular integrity	Prolonged storage or smear damage

4、Maturation Stages of Eosinophils in Bone Marrow

4.1 Eosinophilic myelocytes

(1) Nuclear shape and chromatin

The nucleus of eosinophilic myelocytes is usually round, oval, or mildly indented. Chromatin is coarser than in blasts but not fully mature. Nucleoli are usually not prominent or gradually disappear.

(2) Cytoplasmic granules

More obvious eosinophilic granules begin to appear in the cytoplasm. These granules may be relatively coarse but not yet completely uniform in distribution. This stage is important for recognizing eosinophilic differentiation.

(3) Key interpretation points

Eosinophilic myelocytes should be distinguished from neutrophilic myelocytes and abnormal granular cells. If eosinophilic granules appear early, are coarse, and coexist with immature nuclear development, the overall granulocytic development in bone marrow should be evaluated.

4.2 Eosinophilic metamyelocytes

(1) Nuclear shape changes

The nucleus of eosinophilic metamyelocytes becomes eccentric and may appear kidney-shaped or indented. Chromatin becomes more condensed. Compared with myelocytes, the nuclear-cytoplasmic ratio decreases.

(2) Granule maturation

Eosinophilic granules become more abundant and their color becomes closer to that of mature eosinophils. Granules are widely distributed and are often the main basis for identifying this stage.

(3) Morphological significance

An increased metamyelocyte stage in bone marrow can be seen in reactive eosinophilic proliferation and in some myeloid neoplasms. Blast proportion, other granulocytic development, and erythroid-megakaryocytic changes should be assessed simultaneously.

4.3 Eosinophilic band cells and segmented cells

(1) Band stage

The nucleus is band-shaped, curved, or rod-like, with dense coarse chromatin and mature cytoplasmic granules. This stage is an important form before mature eosinophil release from bone marrow.

(2) Segmented stage

Segmented eosinophils resemble mature cells seen in peripheral blood. When the proportion of mature eosinophils increases in bone marrow, it should be determined whether this is part of overall eosinophilic proliferation.

(3) Maturation continuity

In normal or reactive proliferation, eosinophils usually show continuous maturation across stages. If one stage is abnormally accumulated, development appears asynchronous, or blasts are increased, abnormal hematopoiesis should be considered.

Table 4 Interpretation of Eosinophil Maturation Stages in Bone Marrow

Maturation stage	Nuclear features	Granule features	Interpretation focus
Eosinophilic myelocyte	Round, oval, or mildly indented	Eosinophilic granules begin to appear clearly	Identifying eosinophilic differentiation
Eosinophilic metamyelocyte	Indented, eccentric nucleus; coarser chromatin	Increased granules and stronger color	Assessing continuity of maturation
Eosinophilic band cell	Band-shaped or rod-like nucleus	Relatively mature granules	Evaluating the pre-release stage
Eosinophilic segmented cell	Bilobed or segmented nucleus	Coarse orange-red granules	Corresponds to mature eosinophils
Abnormal eosinophilic precursor	Asynchronous nuclear-cytoplasmic development	Abnormal or uneven granules	Requires screening for clonal disease

5、Morphological Observation in Eosinophilia

5.1 Reactive eosinophilia

(1) Common backgrounds

Reactive eosinophilia may occur in allergic diseases, asthma, parasitic infection, drug reactions, skin diseases, rheumatic and autoimmune diseases, and certain post-infectious states. Morphologically, it is usually dominated by increased mature eosinophils.

(2) Morphological features

In reactive eosinophilia, eosinophils are mostly regular in morphology, with clear bilobed nuclei and coarse orange-red granules. Mild activation changes may be seen, such as uneven granule distribution, mild degranulation, or cytoplasmic vacuoles, but obvious atypia is usually absent.

(3) Interpretation approach

Reactive eosinophilia should be interpreted with absolute eosinophil count, clinical history, medication history, allergy markers, parasite testing, and other inflammatory indicators. Morphology alone cannot determine the exact trigger.

5.2 Clonal eosinophilia

(1) Suggestive clues

If eosinophilia is accompanied by marked leukocytosis, anemia, platelet abnormalities, splenomegaly, increased blasts, obvious bone marrow proliferation, or other granulocytic abnormalities, a clonal disorder should be considered.

(2) Morphological abnormalities

In a clonal background, eosinophils may show reduced granules, uneven granule size, abnormally coarse granules, abnormal nuclear segmentation, nuclear-cytoplasmic developmental asynchrony, or an abnormal proportion of immature eosinophilic cells. Some cases may also show basophilia or other myeloid abnormalities.

(3) Follow-up testing

Morphology provides only clues. Suspected clonal eosinophilia should be further confirmed by bone marrow examination, flow cytometry, karyotyping, FISH, fusion gene testing, and related assays.

5.3 Hypereosinophilic states

(1) Key points in morphological observation

In hypereosinophilic states, attention should be paid to the proportion and absolute count of mature eosinophils in peripheral blood, the presence of immature cells, accompanying abnormalities in other leukocytes, and whether eosinophilic differentiation in bone marrow is continuous.

(2) Association with tissue injury

Eosinophilia may be associated with tissue infiltration and organ damage, but smear morphology cannot directly assess the extent of tissue injury. If cardiac, pulmonary, cutaneous, gastrointestinal, or nervous system manifestations are present, clinical and histological evaluation is required.

(3) Dynamic monitoring

Morphological observation can be used to monitor changes in eosinophil proportion and morphology before and after model treatment, stimulation experiments, or interventions. If abnormal morphology persists after changes in eosinophil number, possible clonal disease, sustained activation, or experimental-condition effects should be considered.

Table 5 Morphological Clues in Eosinophilia

Type	Morphological features	Common accompanying findings	Follow-up direction
Reactive eosinophilia	Mostly mature forms with regular granules	Allergy, infection, drug exposure, inflammatory background	Clinical history and laboratory indicators
Parasite-related eosinophilia	Increased mature eosinophils	May be accompanied by elevated total IgE or tissue symptoms	Parasitological and serological testing
Drug reaction-related eosinophilia	May show mild activation or degranulation	Rash, fever, liver or kidney injury	Medication history and systemic assessment
Clonal eosinophilia	Granule abnormalities, nuclear abnormalities, increased immature cells	Leukocytosis, splenomegaly, anemia, or platelet abnormalities	Bone marrow, genetic, and molecular testing
Hypereosinophilic state	Marked increase, possibly with abnormal morphology	Organ involvement or tissue infiltration	Clinical classification and mechanism testing

6、Abnormal Eosinophil Morphology

6.1 Granule abnormalities

(1) Reduced granules

Reduced granules appear as sparse eosinophilic granules in the cytoplasm, making cell identification more difficult. This should be distinguished from insufficient staining, degranulation, and smear damage.

(2) Uneven granule size

Markedly variable granule size may suggest abnormal development or a clonal background, but smear quality and staining conditions can also contribute. Repeated observation across multiple cells is required before interpretation.

(3) Degranulation

Degranulation appears as reduced cytoplasmic granules, granule leakage, or scattered red granules around the cell. It may occur in activated cells, poorly preserved samples, or mechanically damaged smears, and should be interpreted with the overall smear background.

6.2 Nuclear abnormalities

(1) Hyposegmentation or abnormal segmentation

Insufficient nuclear segmentation, irregular nuclear shape, or abnormal chromatin connections may be seen in dysplasia or reactive change. If other granulocytic abnormalities are also present, myelodysplasia or myeloid clonal disease should be considered.

(2) Hypersegmentation

Hypersegmented eosinophils are uncommon and should be distinguished from neutrophils. Granule color and size remain key distinguishing features.

(3) Nuclear-cytoplasmic developmental asynchrony

An immature nucleus with mature granules, or a mature nucleus with abnormal cytoplasm, suggests developmental asynchrony. This finding is more meaningful in bone marrow smears.

6.3 Cytoplasmic abnormalities

(1) Vacuole formation

Cytoplasmic vacuoles may be seen in cellular activation, poor sample preservation, or abnormal cellular states. A small number of vacuoles may have limited significance, while extensive vacuolization should be interpreted in relation to infection, inflammation, or cell injury.

(2) Increased cytoplasmic basophilia

Immature eosinophils or activated cells may show bluer cytoplasm. If granules are also atypical, distinction from basophils, abnormal monocytes, or immature granulocytes is required.

(3) Cell fragmentation

Cell fragmentation may produce free eosinophilic granules, which can be mistaken for background precipitates or microbial structures. Interpretation should assess whether the granules are associated with cell remnants and exclude smear preparation damage.

Table 6 Abnormal Eosinophil Morphology and Significance

Abnormal feature	Morphological characteristics	Possible implication	Interpretation notes
Reduced granules	Sparse cytoplasmic granules	Developmental abnormality, degranulation, insufficient staining	Technical factors must be excluded
Uneven granule size	Obvious differences in size and color	Abnormal development or clonal background	Repeated observation in multiple cells required
Granule leakage	Scattered red granules around cells	Cell activation or smear damage	Note sample storage time
Abnormal nuclear segmentation	Hyposegmentation, irregular segmentation	Dysplasia or reactive change	Interpret with other granulocytic morphology
Nuclear-cytoplasmic asynchrony	Nuclear and granule maturation are discordant	Possible myeloid abnormality	More meaningful in bone marrow
Cytoplasmic vacuoles	Obvious cytoplasmic vacuoles	Activation, injury, or abnormal state	Interpret with whole-smear background
Cytoplasmic fragmentation	Incomplete cellular structure	Smear damage or increased cell fragility	Should not be used alone as disease evidence

7、Product Selection for Eosinophil Morphological Observation

Table 7 Staining Solutions and Kits Related to Eosinophil Morphological Observation

Cat. No.	Product Name	Grade/Purity/Specification	Product Category	Applicable observation scenario	Methodological application positioning
E1511531	Eosinophil Staining Solution	BioReagent,Biological Stain,for microscopy	Specific staining solution	Eosinophil morphological observation	Directly corresponds to eosinophil observation and is the core staining solution in this article
W1508772	Wright Stain Solution (ready-to-use)	ready-to-use,Biological Stain,Suitable for microbiology,for microscopy,BioReagent	Romanowsky-type ready-to-use stain	Peripheral blood smear; bone marrow smear	Used for leukocyte differential count and observation of eosinophil granules, nuclear shape, and maturation status
W743386	Wright Staining Kit	BioReagent, Biological Stain, for microscopy	Romanowsky-type ready-to-use kit	Peripheral blood smear; bone marrow smear	Standardized Wright staining workflow, suitable for routine hematologic cytomorphology
M743374	Wright-Giemsa Staining Kit	BioReagent, Biological Stain, for microscopy	Romanowsky-type ready-to-use kit	Peripheral blood smear; bone marrow smear	Suitable for simultaneous observation of eosinophilic granules, chromatin, granulocytic maturation stages, and accompanying blood cell abnormalities
G743377	Giemsa Staining Solution	BioReagent, Biological Stain, for microscopy, 10X	Romanowsky-type ready-to-use stain	Blood smear; bone marrow smear; parasite-related samples	Used for eosinophil and other leukocyte morphology observation; also suitable for morphological review in parasite-associated backgrounds
G1508184	Giemsa Staining Solution (Ready-to-use)	BioReagent,ready-to-use,Biological Stain,Suitable for microbiology,for microscopy	Romanowsky-type ready-to-use stain	Blood smear; bone marrow smear; some microbiology-related samples	Suitable for rapid establishment of Giemsa staining workflow for leukocyte nuclear-cytoplasmic structures and eosinophilic granules
M1510448	May-Grunwald Stain Solution	BioReagent,Biological Stain,for microscopy,Suitable for microbiology	May-Grünwald staining solution	Bone marrow smear; cytology smear; MGG system	Used in the first stage of May-Grünwald-Giemsa staining to help display cytoplasmic background and nuclear-cytoplasmic layering
D774859	Diff-Quik Staining Solution	BioReagent, for microscopy, Biological Stain	Rapid Romanowsky-type stain	Rapid cytology evaluation; aspiration smear; rapid morphological observation	Used for rapid display of eosinophil granules and leukocyte morphology, suitable for screening or on-site evaluation
D1511557	Diff-Quik Stain (Fixative-Free)	BioReagent,Bioactive,for microscopy	Rapid Romanowsky-type stain	Already fixed smears; rapid cytology staining	Suitable for rapid morphological staining when fixation has already been performed or needs to be independently controlled
H1508526	Hematoxylin-Eosin (HE) High-Definition Consistent Staining Kit (High-Definition Stable Staining)	BioReagent,for microscopy,Biological Stain	HE tissue staining kit	Eosinophil infiltration observation in tissue sections	Suitable for observing eosinophilic infiltration, inflammatory background, and tissue structural changes in histopathology
H1508460	Hematoxylin-Eosin (HE) Staining Kit (with Differentiating Solution)	BioReagent,for microscopy,Biological Stain	HE tissue staining kit	Tissue sections	Used to identify eosinophils and inflammatory infiltration areas in routine HE-stained tissue sections
H1508459	Hematoxylin-Eosin (HE) Staining Kit (with Differentiating Solution and Bluing Solution)	BioReagent,for microscopy,Biological Stain	HE tissue staining kit	Tissue sections	Complete differentiation and bluing steps, suitable for simultaneous observation of tissue structure and inflammatory cell morphology
H1506002	Modified Hematoxylin-Eosin (HE) Staining Kit	BioReagent,for cell culture,for microscopy	Modified HE staining kit	Tissue sections; cultured cell samples	Can be used to observe eosinophilic staining background in tissue or cell samples; not preferred for peripheral blood smears
E489517	Ematoxylin-Eosin Stain		HE ready-to-use stain	Tissue sections	Used for tissue-section observation of eosinophil infiltration and histopathological background
E196384	Eosin Staining Solution	5%(w/v)	Acidic dye component	HE staining; Romanowsky system component	Eosin-type acidic dye can stain eosinophilic granules, red blood cells, and cytoplasmic proteins red to orange-red
E774787	Eosin Staining Solution (0.5% alcoholic solution )	BioReagent, Biological Stain, for microscopy, Water Soluble, 0.5%	Acidic dye component	Tissue/cell staining support	Can be used as an aqueous eosin component to explain the staining logic of eosinophilic structures
E774785	Eosin Staining Solution ( 1% aqueous solution)	BioReagent, Biological Stain, for microscopy, Water Soluble, 1%	Acidic dye component	Tissue/cell staining support	Used for staining cytoplasm, red blood cells, and eosinophilic structures; not a complete leukocyte differential staining system
E774784	Eosin Staining Solution (0.25% alcoholic solution)	BioReagent, Biological Stain, for microscopy, Alcohol Soluble, 0.25%	Acidic dye component	HE or compound staining support	Can serve as an alcohol-soluble eosin component for explaining eosinophilic granule and cytoplasmic protein staining
E1507828	Eosin Staining Solution (Alcohol-Soluble, 0.5%)	BioReagent,Biological Stain,for microscopy,0.5%	Acidic dye component	HE or compound staining support	Can be used as a component related to eosinophilic structure staining to explain eosin’s role in staining granules and cytoplasm
E774788	Eosin Staining Solution (1% alcoholic solution )	Alcohol Soluble, 1%	Acidic dye component	HE or compound staining support	Suitable as an alcohol-soluble eosin component; not an independent method for eosinophil morphological observation
E301878	Water Soluble Eosin Y Stainin Solution		Acidic dye component	Tissue/cell staining support	Supplementary eosin-type acidic dye item for explaining eosinophilic structure staining
E301879	Alcohol Soluble Eosin Y Stainin Solution		Acidic dye component	Tissue/cell staining support	Alcohol-soluble eosin-related product for explaining staining of eosinophilic granules, cytoplasm, and red blood cells
L774207	Loeffler's Methylene Blue Staining Solution	BioReagent, Biological Stain, for microscopy, 0.6%	Basic thiazine dye component	Romanowsky system component explanation	Used to explain nuclear acid, chromatin, and basophilic structure staining, forming nuclear-cytoplasmic contrast with eosinophilic granule observation
L1509206	Löffler's Methylene Blue Staining Solution (0.1%)	BioReagent,for microscopy,Biological Stain	Basic thiazine dye component	Romanowsky system component explanation	Methylene blue-type dye product for mechanism and component explanation
L1509207	Lv's alkaline methylene blue staining solution (0.23%)	BioReagent,for microscopy,Biological Stain,0.23%	Basic thiazine dye component	Romanowsky system component explanation	Used to explain the role of basic dyes in staining nucleic acids and basophilic structures
L1509208	Löffler's Methylene Blue Staining Solution (0.4%)	BioReagent,Biological Stain,for microscopy,0.4%	Basic thiazine dye component	Romanowsky system component explanation	Methylene blue-type component product used to supplement staining mechanisms for eosinophil nuclear-shape observation
U1511114	Unna Alkaline Methylene Blue Staining Solution	BioReagent,Biological Stain,for microscopy	Basic thiazine dye component	Romanowsky system component explanation	Used to explain the staining logic of alkaline methylene blue-type dyes binding to nucleic acids and acidic cellular components
N1511106	New Methylene Blue Stain Solution	BioReagent,for microscopy,Biological Stain	Thiazine dye-related product	Hematologic staining supplement	Related to thiazine dyes and hematologic staining; may serve as a mechanism supplement but is not a core classic stain for eosinophilic granule observation

Table 8 Auxiliary Validation and Mechanism Research Products Related to Eosinophil Morphological Observation

Cat. No.	Product Name	Grade/Purity/Specification	Product Category	Related direction	Methodological application positioning
E1473580	EPX Human Pre-designed siRNA Set A		EPX gene silencing tool	Eosinophil granule protein mechanism research	Used for EPX gene silencing to study regulation of eosinophil peroxidase expression; not a morphology staining product
rp329572	Recombinant Human EPX Protein	≥90%(SDS-PAGE)	Recombinant EPX protein	Eosinophil granule protein validation	Can serve as positive material for EPX-related antibodies, ELISA, or functional experiments in eosinophil granule protein research
EJ1515207	Mouse Eosinophil Peroxidase (EPX) ELISA Kit	BioReagent	EPX ELISA kit	Eosinophil activation/degranulation detection	Used for quantitative detection of mouse EPX, supporting evaluation of eosinophil activation or granule protein release
Ab125316	Ribonuclease 3/ECP Antibody	Carrier Free, See COA	ECP antibody	Eosinophil cationic protein localization/validation	ECP is an eosinophil granule-associated protein and can be used for immunostaining, protein detection, or degranulation-related research
EJ1512730	Mouse Eosinophil Cationic Protein (ECP) ELISA Kit	BioReagent	ECP ELISA kit	Eosinophil activation/granule protein detection	Used for mouse ECP quantification, suitable for auxiliary explanation of eosinophil activation and granule protein release
rp151552	Recombinant Human Siglec-8 Protein	Animal Free,Carrier Free,Bioactive,ActiBioPure™,His Tag,≥95%(SDS-PAGE)	Recombinant Siglec-8 protein	Surface marker validation	Used for antibody-binding validation, standards, or mechanistic experiments related to Siglec-8-mediated eosinophil identification
C1460980	CCR3 Human Pre-designed siRNA Set A		CCR3 gene silencing tool	Eosinophil chemokine receptor research	CCR3 is an eosinophil chemotaxis-related receptor and can be used for human CCR3 knockdown experiments
C1468229	Ccr3 Mouse Pre-designed siRNA Set A		CCR3 gene silencing tool	Mouse eosinophil chemotaxis mechanism	Used for mouse Ccr3 knockdown, suitable for eosinophil migration, chemotaxis, and inflammation model research
C1485582	Ccr3 Rat Pre-designed siRNA Set A		CCR3 gene silencing tool	Rat eosinophil chemotaxis mechanism	Used for rat Ccr3 knockdown, suitable for chemokine receptor mechanism research and model validation
Ab093543	Recombinant CCR3 Antibody	ExactAb™, Validated, Recombinant, 1.5 mg/mL	CCR3 antibody	Eosinophil surface marker/chemokine receptor	Used for CCR3 protein detection or localization, supporting confirmation of eosinophil-related chemokine receptor expression
EJ1512468	Mouse Chemokine C-C-Motif Receptor 3 (CCR3) ELISA Kit	BioReagent	CCR3 ELISA kit	Mouse CCR3 quantitative detection	Used for mouse CCR3 level detection, suitable for eosinophil chemotaxis pathway research
C970562	CCR3 antagonist 1	≥98%	CCR3 antagonist	Pharmacological intervention in chemotaxis pathway	Used for CCR3 pathway inhibition experiments, supporting analysis of eosinophil recruitment and migration mechanisms
S275456	SB 297006	≥98%	CCR3 antagonist	Pharmacological intervention in chemotaxis pathway	CCR3 inhibitor for eosinophil chemotaxis-related models
S274805	SB 328437	Moligand™, ≥98%	CCR3 antagonist	Pharmacological intervention in chemotaxis pathway	Used for research on CCR3-mediated eosinophil migration and inflammatory responses
U287732	UCB 35625	≥98%(HPLC)	CCR1/CCR3 antagonist	Pharmacological intervention in chemotaxis pathway	Used in CCR3-related chemotaxis experiments; because it also acts on CCR1, receptor specificity must be considered
P744618	pLenti-CCR3-sgRNA		CCR3 knockout validation lysate	CCR3 protein detection control	Can serve as a negative/knockout validation material for CCR3 antibody or protein detection
P744619	pLenti-CCR3-sgRNA		CCR3 knockout validation lysate	CCR3 transcript-level detection control	Can be used for CCR3 gene expression detection or qPCR validation
rp174313	IL-5	Moligand™	IL-5 protein	Eosinophil differentiation/activation stimulation	IL-5 pathway stimulant for eosinophil-related cell models or mechanistic research
rp181291	Recombinant Human IL-5 Protein	Animal Free,Carrier Free,Bioactive,ActiBioPure™,High Performance,His Tag,≥95%(SDS-PAGE),expressed in HEK293; See COA	Recombinant human IL-5 protein	Human IL-5 pathway research	Used for human eosinophil differentiation, activation, survival, or signaling research
rp154233	Recombinant Mouse IL-5 Protein	Animal Free,Carrier Free,Bioactive,ActiBioPure™,High Performance,His Tag,≥97%(SDS-PAGE)	Recombinant mouse IL-5 protein	Mouse model/cell experiments	Suitable for mouse eosinophil-related models and IL-5 stimulation experiments
rp155122	Recombinant Rat IL-5 Protein	Animal Free,Carrier Free,Bioactive,ActiBioPure™,High Performance,His Tag,≥97%(SDS-PAGE)	Recombinant rat IL-5 protein	Rat model/cell experiments	Suitable for rat eosinophil-related models and IL-5 stimulation experiments
Ab110351	IL-5 Rat mAb	Carrier Free,Azide Free,Validated,PBS Only,≥95%(SDS-PAGE),See COA	IL-5 antibody	IL-5 detection/blocking experiment	Used for IL-5 protein detection or functional blocking experiments
Ab110356	Recombinant IL-5 Antibody	Carrier Free,Recombinant,ExactAb™,Azide Free,Validated,PBS Only,See COA	Recombinant IL-5 antibody	IL-5 detection/mechanism research	Used for IL-5 detection, pathway validation, or blocking experiments
Ab110358	Recombinant IL-5 Antibody	Carrier Free,Recombinant,ExactAb™,Azide Free,Validated,PBS Only,See COA	Recombinant IL-5 antibody	IL-5 detection/mechanism research	Used for IL-5-related experimental validation
EJ1514387	Human Interleukin 5 (IL-5) ELISA Kit	BioReagent	IL-5 ELISA kit	Human IL-5 quantitative detection	Used to detect IL-5 levels in eosinophil-related inflammatory backgrounds
EJ1512161	Rat Interleukin 5 (IL-5) ELISA Kit	BioReagent	IL-5 ELISA kit	Rat IL-5 quantitative detection	Suitable for analyzing the relationship between IL-5 pathway and eosinophilia in rat models
EJ1512934	Mouse Interleukin 5 (IL-5) ELISA Kit	BioReagent	IL-5 ELISA kit	Mouse IL-5 quantitative detection	Suitable for detecting IL-5 in mouse allergy, asthma, or parasitic infection models
EJ1511832	Guinea Pig Interleukin 5 (IL-5) ELISA Kit	BioReagent	IL-5 ELISA kit	Guinea pig IL-5 quantitative detection	Used for IL-5-related eosinophilic inflammation research in guinea pig models

Eosinophil morphological observation should focus on nuclear shape, cytoplasmic granules, maturation stage, and accompanying cellular abnormalities. Mature eosinophils have a typical bilobed nucleus and coarse orange-red granules, but when abnormal increase, granule changes, or increased immature stages are present, results must be interpreted together with peripheral blood counts, bone marrow morphology, clinical background, and molecular genetic testing.

For more related articles, please see below:

[1] Direct eosinophil counting assay