GO:0097225 sperm midpiece: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0097225 sperm midpiece is the highly organized segment of the sperm flagellum that begins at the connecting piece and ends at the annulus, characterized by nine outer dense fibers (ODFs) and a mitochondrial sheath.
• The midpiece is the primary site of ATP production for sperm motility, housing mitochondria that generate energy for flagellar beating.
• Midpiece defects, including abnormal morphology and DNA fragmentation, are associated with male infertility and reduced sperm quality.
• CCDC112 is a key protein required for sperm midpiece formation and epididymal maturation, influencing flagellar waveform and motility.
• Midpiece size does not correlate with mitochondrial DNA copy number in some species, indicating complex regulation of mitochondrial content and function.
• Research on the sperm midpiece employs morphometric analysis, knockout models, and imaging to understand its role in fertility and disease.
Description
The sperm midpiece (GO:0097225) is a specialized compartment of the sperm flagellum that is essential for energy production and motility. It is defined as the segment beginning at the connecting piece and terminating at the annulus, marked by nine outer dense fibers (ODFs) surrounding the axoneme and a mitochondrial sheath. This structure is critical for providing the ATP required for flagellar beating and sperm movement. Understanding the midpiece is fundamental for reproductive biology and andrology, as defects in its formation or function are linked to male infertility and abnormal sperm parameters. Recent studies have identified molecular players such as CCDC112 that drive midpiece maturation and establish optimal flagellar waveform. Moreover, midpiece morphometry and mitochondrial DNA content are active areas of research, with implications for assessing sperm quality across species.
sperm midpiece At A Glance
| GO ID | GO:0097225 |
|---|---|
| GO term | sperm midpiece |
| Ontology | cellular_component |
| Synonym | none |
| Major function | ATP production for sperm motility and structural support of the flagellum |
| Location | Sperm flagellum, between connecting piece and annulus |
| Key structures | Outer dense fibers (ODFs), mitochondrial sheath, axoneme |
| Associated genes | CCDC112, and other genes involved in midpiece formation and function |
What Is GO:0097225?
The sperm midpiece is the highly organized segment of the sperm flagellum that begins at the connecting piece and is characterized by the presence of nine outer dense fibers (ODFs) that lie outside each of the nine outer axonemal microtubule doublets, and by a sheath of mitochondria that encloses the ODFs and the axoneme; the midpiece terminates about one-fourth of the way down the sperm flagellum at the annulus, which marks the beginning of the principal piece.
Why Is sperm midpiece Important in Cell Biology?
The sperm midpiece is indispensable for male fertility because it houses the mitochondria that generate ATP for flagellar beating and sperm motility. Disruptions in midpiece structure or function can lead to asthenozoospermia and male infertility. Recent research has uncovered molecular mechanisms of midpiece formation, including the role of CCDC112, which is essential for epididymal maturation and optimal flagellar waveform. Additionally, midpiece morphometry and mitochondrial DNA copy number are being explored as biomarkers of sperm quality, although their relationship remains complex. Understanding the midpiece at the molecular level can inform diagnostic and therapeutic strategies for male reproductive health.
• Provides the primary energy source for sperm motility through mitochondrial ATP production.
• Structural integrity of the midpiece is essential for normal flagellar beating and sperm movement.
• Midpiece defects are associated with increased sperm DNA fragmentation and male infertility.
• CCDC112-dependent midpiece formation is critical for epididymal maturation and optimal flagellar waveform.
• Midpiece morphometry can serve as a biomarker for sperm quality in andrology.
• Mitochondrial DNA copy number in the midpiece may reflect mitochondrial function but is not always correlated with midpiece size.
• Abnormal midpiece morphology is observed in bulls with no reduction in sperm kinematics, indicating species-specific adaptations.
• Signaling pathways in the midpiece regulate quiescence and survival in the cauda epididymis.
• Regulatory systems in the midpiece differ from those in the principal piece, highlighting functional specialization.
• Research on midpiece genes like CCDC112 offers potential targets for male contraception and fertility treatments.
Core Biology of the Sperm Midpiece
What Happens During sperm midpiece formation?
In simple terms: The midpiece forms as sperm mature in the epididymis, assembling outer dense fibers and mitochondria around the axoneme.
During spermiogenesis and epididymal maturation, the sperm midpiece undergoes a highly regulated assembly process. The connecting piece gives rise to the nine outer dense fibers (ODFs) that surround the axonemal microtubule doublets, and mitochondria are recruited to form a sheath around the ODFs and axoneme. Recent studies have identified CCDC112 as a novel protein that drives midpiece formation and epididymal maturation, ensuring an optimal flagellar waveform. This process is essential for the midpiece to become a functional energy-producing compartment.
Structure and Composition of sperm midpiece
In simple terms: The midpiece is made of a central axoneme, nine outer dense fibers, and a mitochondrial sheath that wraps around them.
The sperm midpiece is structurally defined by the presence of nine outer dense fibers (ODFs) that lie outside each of the nine outer axonemal microtubule doublets, and by a sheath of mitochondria that encloses the ODFs and the axoneme. This arrangement is highly organized and terminates at the annulus, which marks the beginning of the principal piece. The mitochondrial sheath is critical for ATP production, and its size and composition can vary among species. Morphometric analyses have revealed that midpiece dimensions change during capacitation, reflecting dynamic structural remodeling.
Molecular Mechanism of sperm midpiece
In simple terms: The midpiece uses mitochondrial oxidative phosphorylation to produce ATP, and its formation is controlled by specific proteins like CCDC112.
The molecular mechanism of the sperm midpiece centers on energy production and structural assembly. Mitochondria within the midpiece generate ATP through oxidative phosphorylation, which fuels dynein motors for flagellar beating. The assembly of the midpiece requires CCDC112, a protein that is essential for the formation of the mitochondrial sheath and ODFs, and for establishing an optimal flagellar waveform. Additionally, signaling pathways in the midpiece regulate quiescence and survival in the cauda epididymis, ensuring that sperm remain viable until ejaculation. Regulatory systems in the midpiece differ from those in the principal piece, allowing compartment-specific control of motility.
Regulation of sperm midpiece function
In simple terms: The midpiece is regulated by signaling molecules that control energy production and structural integrity.
Regulation of the sperm midpiece involves cell signaling pathways that ensure quiescence and survival in the cauda epididymis. Different regulatory systems operate in the midpiece and principal piece of the mammalian sperm flagellum, enabling region-specific control of motility and energy metabolism. The formation and maturation of the midpiece are dependent on CCDC112, which coordinates the assembly of outer dense fibers and the mitochondrial sheath. Morphometric changes during capacitation further indicate that the midpiece is dynamically regulated in response to physiological cues.
Key Genes Involved in GO:0097225 sperm midpiece
The following genes and proteins are critically involved in the formation, function, and regulation of the sperm midpiece.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CCDC112 | Required for sperm midpiece formation and epididymal maturation; influences flagellar waveform | Knockout studies show defective midpiece and impaired motility |
| ODF1 | Outer dense fiber component; provides structural support to the midpiece | Marker of midpiece integrity; potential target for male contraception |
| ODF2 | Outer dense fiber component; essential for flagellar stability | Mutations linked to sperm morphological defects |
| AKAP4 | Fibrous sheath protein; involved in signaling and energy regulation | Associated with sperm motility and fertility |
| SPAG16 | Axonemal component; required for flagellar assembly | Defects cause primary ciliary dyskinesia and male infertility |
| DNAH1 | Dynein heavy chain; generates flagellar beating force | Mutations cause asthenozoospermia |
| DNAH2 | Dynein heavy chain; involved in ciliary and flagellar motility | Potential biomarker for sperm quality |
| CFAP43 | Cilia- and flagella-associated protein; important for axoneme structure | Mutations linked to male infertility |
| CFAP44 | Cilia- and flagella-associated protein; required for normal flagellar function | Associated with multiple morphological abnormalities of the flagella |
| TEKT1 | Tektin; structural component of flagellar microtubules | Contributes to flagellar stability and motility |
| TEKT2 | Tektin; involved in flagellar assembly | Potential role in sperm midpiece organization |
| TEKT3 | Tektin; important for flagellar structure | Associated with sperm motility defects |
| TEKT4 | Tektin; component of the axoneme | May influence midpiece function |
| TEKT5 | Tektin; structural protein of the flagellum | Research on sperm morphology |
| SPATA6 | Spermatogenesis-associated protein; involved in midpiece formation | Knockout mice show defective midpiece and infertility |
| SPATA16 | Spermatogenesis-associated protein; required for acrosome and midpiece development | Mutations cause globozoospermia |
| GOPC | Golgi-associated PDZ and coiled-coil motif containing; involved in acrosome and midpiece formation | Knockout models show abnormal midpiece |
| MARCH10 | E3 ubiquitin-protein ligase; regulates midpiece assembly | Potential role in sperm maturation |
How Is sperm midpiece Regulated?
The sperm midpiece is regulated by cell signaling pathways that ensure quiescence and survival in the cauda epididymis. Different regulatory systems operate in the midpiece and principal piece of the mammalian sperm flagellum, allowing compartment-specific control of motility and energy metabolism. The formation and maturation of the midpiece are dependent on CCDC112, which coordinates the assembly of outer dense fibers and the mitochondrial sheath. Morphometric changes during capacitation further indicate that the midpiece is dynamically regulated in response to physiological cues.
sperm midpiece and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CCDC112 | Defective midpiece formation and epididymal maturation; male infertility | Knockout mouse model |
| ODF1 | Outer dense fiber defects; asthenozoospermia | Point mutation knock-in mouse |
| AKAP4 | Fibrous sheath dysplasia; sperm motility defects | Knockout mouse |
| DNAH1 | Primary ciliary dyskinesia; multiple morphological abnormalities of the flagella | Knock-in mouse |
| SPATA6 | Midpiece defects; male infertility | Knockout mouse |
Male Infertility and Midpiece Defects
Defects in sperm midpiece structure and function are associated with male infertility. A high percentage of midpiece defects in bull sperm has been observed without reduction in sperm kinematics, indicating species-specific adaptations. In humans, midpiece details correlate with DNA fragmentation, suggesting that midpiece abnormalities may contribute to sperm DNA damage and reduced fertility. Morphometric analysis of the sperm midpiece during capacitation reveals dynamic changes that may be disrupted in infertile men.
CCDC112 and Epididymal Maturation
CCDC112 is a novel protein that plays a critical role in sperm midpiece formation and epididymal maturation. Disruption of CCDC112 leads to defective midpiece formation and impaired flagellar waveform, resulting in reduced sperm motility and fertility. This highlights CCDC112 as a potential target for male contraception and a biomarker for sperm quality.
Mitochondrial DNA Copy Number and Midpiece Size
The relationship between sperm mitochondrial DNA copy number and midpiece size is complex. In songbirds, sperm mtDNA copy number is not associated with midpiece size, suggesting that mitochondrial content is regulated independently of midpiece dimensions. This finding has implications for understanding energy metabolism and fertility across species.
From sperm midpiece-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of CCDC112 in midpiece formation? | CCDC112 knockout mouse |
| How do outer dense fiber proteins affect sperm motility? | ODF1 point mutation knock-in mouse |
| Does mitochondrial sheath size correlate with mtDNA copy number? | Songbird model |
| What signaling pathways regulate midpiece quiescence? | Cauda epididymis sperm from knockout mice |
| How does capacitation alter midpiece morphometry? | Human sperm capacitation in vitro |
| Are midpiece defects associated with DNA fragmentation? | Human sperm samples with midpiece abnormalities |
How to Study the sperm midpiece Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Morphometric analysis | Midpiece dimensions and morphology | Assessing sperm quality and capacitation changes |
| Transmission electron microscopy | Ultrastructure of ODFs and mitochondria | Visualizing midpiece defects |
| Knockout mouse models | Gene function in midpiece formation | Studying CCDC112 and other genes |
| Immunofluorescence | Protein localization in the midpiece | Detecting CCDC112 and ODF proteins |
| RT-PCR | Gene expression levels | Quantifying midpiece-related transcripts |
| Western blotting | Protein expression and modifications | Validating knockout phenotypes |
| Sperm motility analysis | Flagellar waveform and kinematics | Assessing functional consequences of midpiece defects |
| Mitochondrial DNA copy number assay | mtDNA quantity | Correlating with midpiece size |
Morphometric Analysis
Morphometric analysis of the sperm midpiece involves measuring dimensions such as length, width, and mitochondrial sheath thickness using light or electron microscopy. This method has been used to assess changes during capacitation and to correlate midpiece details with DNA fragmentation.
Genetic Knockout Models
Knockout mouse models, such as CCDC112 knockout, are essential for studying the role of specific genes in midpiece formation and function. These models reveal defects in midpiece structure, flagellar waveform, and fertility.
Imaging Techniques
Advanced imaging techniques, including transmission electron microscopy and fluorescence microscopy, allow visualization of the midpiece ultrastructure, including outer dense fibers and mitochondrial sheath. These methods are critical for assessing midpiece integrity.
Molecular Biology Assays
Molecular biology assays such as RT-PCR, Western blotting, and immunofluorescence are used to detect expression and localization of midpiece proteins like CCDC112. These techniques help elucidate the molecular mechanisms of midpiece formation.
How CRISPR Can Be Used to Study GO:0097225 sperm midpiece
Knockout
CRISPR knockout of genes such as CCDC112 in mouse models has been used to demonstrate their essential role in sperm midpiece formation and epididymal maturation. These studies reveal that loss of CCDC112 leads to defective midpiece structure and impaired flagellar waveform.
Point Mutation
Point mutation knock-in models can be used to study specific amino acid changes in midpiece proteins, such as ODF1 or AKAP4, to understand their impact on sperm motility and fertility. These models mimic human mutations associated with asthenozoospermia.
Knock-in
Knock-in of tagged versions of midpiece proteins, such as CCDC112-GFP, allows real-time visualization of protein localization and dynamics during midpiece formation. This approach is valuable for understanding the assembly process.
Overexpression
Overexpression of midpiece proteins like CCDC112 or ODF1 in cell lines or transgenic mice can reveal gain-of-function phenotypes and help identify downstream signaling pathways. Overexpression studies complement knockout models to provide a comprehensive understanding of gene function.
How EDITGENE Supports sperm midpiece Research
Researchers studying sperm midpiece-related genes often need to determine whether a candidate gene is causally involved in midpiece formation, function, or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this research, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for sperm midpiece research.
Frequently Asked Questions About sperm midpiece
What is the sperm midpiece (GO:0097225)?
The sperm midpiece is the highly organized segment of the sperm flagellum that begins at the connecting piece and ends at the annulus, characterized by nine outer dense fibers and a mitochondrial sheath.
What genes are involved in sperm midpiece formation?
Key genes include CCDC112, ODF1, ODF2, AKAP4, and SPATA6, among others.
How does the sperm midpiece produce energy?
The midpiece houses mitochondria that generate ATP through oxidative phosphorylation to fuel flagellar beating.
What diseases are associated with sperm midpiece defects?
Midpiece defects are linked to male infertility, asthenozoospermia, and increased sperm DNA fragmentation.
What is the role of CCDC112 in the sperm midpiece?
CCDC112 is required for sperm midpiece formation and epididymal maturation, influencing flagellar waveform and motility.
How is the sperm midpiece studied in research?
Researchers use morphometric analysis, knockout mouse models, imaging techniques, and molecular biology assays.
Does midpiece size correlate with mitochondrial DNA copy number?
In songbirds, sperm mtDNA copy number is not associated with midpiece size, indicating independent regulation.
What are outer dense fibers (ODFs)?
ODFs are nine structural fibers that lie outside the axonemal microtubule doublets in the sperm midpiece, providing support and elasticity.
How does capacitation affect the sperm midpiece?
Capacitation induces morphometric changes in the midpiece, reflecting dynamic remodeling for fertilization.
Can CRISPR be used to study sperm midpiece genes?
Yes, CRISPR knockout and knock-in models are powerful tools to study gene function in midpiece formation and fertility.
Conclusion
The sperm midpiece (GO:0097225) is a structurally and functionally distinct compartment of the sperm flagellum that is essential for energy production and motility. Its formation requires coordinated assembly of outer dense fibers and a mitochondrial sheath, processes that are regulated by specific genes such as CCDC112. Defects in midpiece structure or function are associated with male infertility and abnormal sperm parameters. Continued research using CRISPR models, morphometric analysis, and molecular assays will further elucidate the mechanisms of midpiece biology and may lead to new diagnostic and therapeutic strategies for male reproductive health.
References
- 1. Ibis MA et al.. 2025. The Relationship Between Sperm Midpiece Details and DNA Fragmentation in Human Sperm.. Reprod Sci 32(7):2319-2330 PMID: 40457018
- 2. Bagdonaitė L et al.. 2025. Sperm mtDNA Copy Number Is Not Associated With Midpiece Size Among Songbirds.. Ecol Evol 15(3):e71055 PMID: 40027421
- 3. Skowronek MF et al.. 2025. Morphometric analysis of the sperm midpiece during capacitation.. Tissue Cell 95:102866 PMID: 40157222
- 4. Graffeo ML et al.. 2025. A novel mechanism of sperm midpiece epididymal maturation and the role of CCDC112 in sperm midpiece formation and establishing an optimal flagella waveform.. Cell Commun Signal 23(1):319 PMID: 40598224
- 5. Devi A et al.. 2021. Cell signaling in sperm midpiece ensures quiescence and survival in cauda epididymis.. Reproduction 162(5):339-351 PMID: 34486982
- 6. Suarez SS et al.. 2007. Different regulatory systems operate in the midpiece and principal piece of the mammalian sperm flagellum.. Soc Reprod Fertil Suppl 65:331-4 PMID: 17644973
- 7. Maggi G et al.. 2024. High percentage of midpiece defects in Brangus bull sperm with no reduction in sperm kinematics.. Reprod Domest Anim 59(5):e14585 PMID: 38745503
- 8. Graffeo ML et al.. 2024. A novel CCDC112-dependent process of sperm midpiece formation and epididymal maturation.. bioRxiv PMID: 39574653
