Hubbry Logo
AcrosomeAcrosomeMain
Open search
Acrosome
Community hub
Acrosome
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Acrosome
Acrosome
Acrosome
View on Wikipedia
from Wikipedia
Diagram of a human spermatozoa showing the acrosome

The acrosome is an organelle that develops over the anterior (front) half of the head in the spermatozoa (sperm cells) of humans and many other animals. It is a cap-like structure derived from the Golgi apparatus. In placental mammals, the acrosome contains degradative enzymes (including hyaluronidase and acrosin).[1] These enzymes break down the outer membrane of the ovum,[2] called the zona pellucida, allowing the haploid nucleus in the sperm cell to join with the haploid nucleus in the ovum. This shedding of the acrosome, known as the acrosome reaction, can be stimulated in vitro by substances that a sperm cell may encounter naturally, such as progesterone[3] or follicular fluid, as well as the more commonly used calcium ionophore A23187.[4] This can be done to serve as a positive control when assessing the acrosome reaction of a sperm sample by flow cytometry[5] or fluorescence microscopy. This is usually done after staining with a fluoresceinated lectin such as FITC-PNA, FITC-PSA, FITC-ConA, or fluoresceinated antibody such as FITC-CD46.[6]

In the case of globozoospermia (sperm with round heads), the Golgi apparatus is not transformed into the acrosome, causing male infertility.[7]

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Acrosome

View on Grokipedia
from Grokipedia
The acrosome is a specialized, cap-like membranous that covers the anterior portion of the head in many animal species, including mammals, and is essential for successful fertilization. It consists of an outer acrosomal , an inner acrosomal , and an acrosomal matrix containing hydrolytic enzymes such as acrosin, along with other proteins that facilitate sperm-egg interaction. Evolutionarily conserved as a lysosome-related , the acrosome forms during and plays a in penetrating the egg's protective layers. Biogenesis of the acrosome occurs in four distinct phases during mammalian : the Golgi phase (steps 1–3), where proacrosomal vesicles arise from the Golgi apparatus; the cap phase (steps 4–7), involving vesicle fusion and spreading over the nucleus; the acrosome phase (steps 8–12), with further maturation and anchoring; and the maturation phase (steps 13–16), completing structural refinement. This process relies on intracellular trafficking mechanisms, including SNARE-mediated vesicle fusion, endocytic pathways, and proteins like SPACA1 and DPY19L2 for anchoring, with disruptions often leading to syndromes such as globozoospermia. The acrosome's formation is tightly regulated by factors like acidification via proton pumps and autophagy-related proteins (e.g., Atg7), ensuring its functionality. In function, the acrosome undergoes the —an exocytotic event triggered by contact with the egg's —releasing that degrade the matrix of the zona, allowing the to reach and fuse with the egg's plasma membrane. This reaction is calcium-dependent and involves membrane fusion regulated by proteins such as Munc18-1. Successful fusion triggers the in the egg, preventing by blocking additional entries. Defects in acrosome integrity or reaction, as seen in acrosomeless models, render fertilization impossible, highlighting its indispensable role in across species.

Anatomy and Development

Structure

The acrosome is a cap-like that covers the anterior two-thirds of the nucleus in mature spermatozoa, originating from the Golgi apparatus during . This structure lies immediately beneath the plasma membrane of the head, forming a specialized secretory vesicle essential for reproductive function. In terms of morphology, the acrosome exhibits a regionally differentiated structure, consisting of a thin apical (or marginal) region at the anterior tip, a thicker principal segment in the mid-anterior portion, and a narrower posterior equatorial segment that borders the postacrosomal . These segments vary in thickness and density, with the principal segment being the most prominent and encompassing the bulk of the acrosomal . Across mammalian , acrosomal shows notable diversity; in humans, it is typically flattened and oval, whereas in some other mammals, such as certain or , it adopts a more conical form. Ultrastructural analysis via electron microscopy reveals the acrosome as a membrane-bound vesicle containing electron-dense material, delimited by an outer acrosomal closely apposed to the overlying plasma and an inner acrosomal that adheres to the underlying . A layer of periacrosomal material, composed of filamentous and granular elements, surrounds the vesicle and provides structural support between the acrosome and the nucleus. In human spermatozoa, the acrosome spans approximately 40-50% of the sperm head length, which measures 4.0-5.0 μm overall, and exhibits a thickness of about 0.1-0.2 μm in its principal region. These dimensions contribute to the streamlined profile of the sperm head, optimizing its hydrodynamic properties during transit.

Formation during Spermatogenesis

The formation of the acrosome begins in early round spermatids during the initial phase of , shortly after completion. In this Golgi phase, proacrosomal vesicles derived from the Golgi apparatus cluster near the concave region of the spermatid nucleus and fuse to form a single acrosomal granule, which initially appears as a small, dense structure attached to the . This fusion process is mediated by vesicular transport mechanisms involving , which facilitate the directed movement of Golgi-derived vesicles to the implantation site on the nucleus. As spermiogenesis progresses into the cap phase, the acrosomal granule enlarges through additional fusions with lysosome-like vesicles, flattens, and spreads dorsally over the anterior portion of the nucleus, forming a cap-like structure that covers approximately one-third to half of the nuclear surface. This spreading is anchored by the acroplaxome, a cytoskeletal plate composed of F-actin and keratin-like proteins that connects the acrosomal to the , ensuring stable attachment during nuclear reshaping. of the manchette, a transient structure forming around the spermatid, play a crucial role in this phase by providing tracks for motor proteins that transport additional vesicular components and contribute to the elongation of the spermatid. In the subsequent acrosome and maturation phases, the acrosome elongates along the ventral nuclear surface, compacts, and differentiates into distinct anterior and posterior regions as the spermatid transitions to an elongated form. Nuclear reshaping is influenced by the attached acrosome, which guides condensation and perinuclear formation, while lysosomal fusions continue to expand the acrosomal until final compaction. Cytoplasmic excess is shed as residual bodies, completing the process. In humans, acrosome biogenesis initiates in stage I round spermatids and completes by stage VII late elongated spermatids, spanning approximately 13-14 days within the overall 74-day cycle. In like mice, the process follows a similar sequence but occurs over 16 discrete steps in a shorter timeline of about 8-10 days for , with more rapid progression in flattening and elongation due to differences in nuclear geometry. These variations highlight conserved mechanisms but underscore adaptations in timing and acrosomal morphology, such as the hook-shaped cap in versus the flatter cap in humans.

Biochemical Composition

Enzymes and Proteins

The acrosome contains a variety of hydrolytic enzymes and structural proteins essential for function during fertilization. These components are primarily stored in the acrosomal matrix and vesicle, where they remain compartmentalized to prevent premature . Among the primary enzymes, acrosin is a key synthesized as an inactive proenzyme, proacrosin, which plays a critical role in digesting the to facilitate penetration. Proacrosin is bound to the acrosomal matrix, ensuring controlled release during the . , present in the acrosome, contributes to the degradation of in the egg's protective layers, aiding progression through the and following the . This acrosomal (e.g., HYAL5) is distinct from the plasma membrane-associated PH-20 (SPAM1), which primarily mediates initial cumulus cell dispersion prior to the . Glycosidases, such as β-N-acetylhexosaminidase (also known as β-N-acetylglucosaminidase), contribute to carbohydrate breakdown in the egg's investments, aiding sperm progression through the zona pellucida. This enzyme is localized within sperm acrosomes and is discharged during the acrosome reaction to modify zona glycoproteins. Structural proteins in the acrosomal matrix include Izumo1, a fusion protein essential for mediating sperm-egg membrane fusion after acrosome reaction. Izumo1 is anchored on the acrosomal membrane and relocates to the equatorial segment upon activation. SP-10 (encoded by ACRV1) serves as an acrosome-specific marker protein, associated with the acrosomal vesicle matrix during spermatogenesis and used to identify acrosomal integrity. Zymogen activation of occurs through , converting it to active acrosin within the acrosomal matrix; this process is regulated by compartmentalization via bonds and non-covalent interactions to inhibit premature activity. Such sequestration in the insoluble matrix fraction delays release until the . Acrosin activity levels provide a quantitative measure of acrosomal function, with fertile typically exhibiting 35 ± 10 μIU per 10^6 as assessed by spectrofluorometric assays.

Vesicular Components

The acrosome features a dual- system critical to its architecture and function. The outer acrosomal (OAM) lies in close apposition or fusion with the overlying plasma , facilitating interactions with the extracellular environment, while the inner acrosomal (IAM) lines the acrosomal lumen and exhibits resistance to premature fusion, preserving compartmental integrity until activation. The lipid composition of these membranes is enriched with and phospholipids, which modulate membrane rigidity and enable dynamic remodeling during maturation. Positioned between the OAM and IAM is the periacrosomal material, an electron-dense substance that imparts to the acrosome. This material incorporates actin-like filaments, which contribute to the mechanical stability of the and potentially aid in maintaining its shape under physiological stresses. The acrosomal interior contains vesicular substructures, including small vesicles that facilitate the compartmentalized storage of hydrolytic components. These substructures help organize the contents within the acidic lumen, where a gradient is maintained at approximately 5.5 through the activity of proton pumps, such as , ensuring optimal conditions for content preservation. Biophysical analyses reveal that acrosomal membrane fluidity evolves during and epididymal maturation, with techniques like (FRAP) demonstrating enhanced lipid lateral diffusion in the OAM and plasma membrane overlay, reflecting adaptations for subsequent exocytotic competence.

Physiological Role

Acrosome Reaction

The acrosome reaction is a calcium-dependent exocytotic process in which the outer acrosomal membrane (OAM) fuses with the overlying sperm plasma membrane, resulting in vesiculation, dispersal of acrosomal contents, and exposure of the inner acrosomal membrane (IAM). This event reorganizes the sperm head's surface architecture, enabling subsequent interactions during fertilization. The reaction releases hydrolytic enzymes that facilitate penetration of the zona pellucida, as detailed in the biochemical composition section. Primary triggers for the acrosome reaction include binding of glycoproteins, such as ZP3 in mammals, to specific surface receptors, which activates G-protein-coupled signaling pathways. Progesterone serves as an alternative stimulus, often encountered in the female reproductive tract, inducing the reaction through receptor-mediated calcium influx. These triggers initiate a coordinated response that is species-specific but conserved in requiring extracellular interaction for physiological relevance. The molecular cascade begins with ligand binding stimulating , generating inositol 1,4,5-trisphosphate (IP3), which binds to IP3 receptors on the and acrosomal membranes to release stored Ca²⁺ into the . This Ca²⁺ elevation promotes OAM-plasma fusion and progressive IAM exposure through SNARE-mediated docking and vesiculation. Concurrently, Ca²⁺ activates , an actin-severing protein, leading to F-actin in the periacrosomal region, which clears the cytoskeletal barrier and facilitates proximity for fusion. The acrosome reaction is commonly visualized using fluorescence microscopy with dyes such as fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA), which binds specifically to intact acrosomes, allowing differentiation between reacted and unreacted sperm. In human sperm, successful induction rates typically range from 20% to 50% following exposure to physiological triggers like progesterone or zona pellucida components in capacitated samples.

Fertilization Process

In mammalian fertilization, sperm first penetrate the cumulus oophorus using surface-anchored hyaluronidases, such as PH-20 (SPAM1), which digest the hyaluronic acid matrix to facilitate access to the zona pellucida. Upon binding the zona pellucida, the acrosome reaction is triggered, releasing acrosomal enzymes that enable penetration through the zona. Acrosin, a serine protease, digests the zona pellucida glycoproteins, creating a pathway for the sperm to traverse this extracellular matrix. This enzymatic action is essential, as acrosin knockout studies in mice demonstrate delayed but not abolished zona penetration, underscoring its supportive role alongside other proteases. The is induced by sperm-zona pellucida interactions, integrating it into the broader penetration sequence without detailing its exocytotic mechanism. As the sperm advances through the zona, the timing of acrosome loss varies: in mice, most fertilizing initiate the reaction prior to zona contact, losing the acrosomal cap during traversal, which exposes the equatorial segment for subsequent interactions. Species variations highlight the acrosome's adaptive role in fertilization outcomes. In polyspermy-tolerant such as birds and reptiles, multiple may penetrate the , with acrosomal enzymes aiding collective dispersion of egg coats, whereas mammals enforce monospermy through rapid zona hardening post-fusion, limiting penetration to a single acrosome-intact . In mammals, acrosome loss typically occurs before or during zona traversal to ensure precise navigation. Regulatory checkpoints maintain acrosomal integrity until the appropriate stage. Decapacitation factors in seminal plasma, including and ions, inhibit premature and by stabilizing the sperm membrane and suppressing hyperactivated motility. Hyperactivation, characterized by vigorous asymmetric flagellar beating, emerges during in the female tract and enhances binding, propelling the toward the . Upon successful zona penetration, the equatorial segment of the sperm head, now exposed post-acrosome reaction, contacts the oolemma to initiate membrane fusion. This fusion is mediated by the interaction between sperm surface protein Izumo1 and receptor Juno, forming the essential complex for merger. Acrosomal integrity directly influences success rates, as compromised acrosomes impair release and fusion competence, reducing penetration efficiency.

Pathophysiology

Acrosome Defects

Acrosome defects encompass a range of structural and functional abnormalities in the sperm acrosome, primarily arising from genetic mutations that disrupt its biogenesis during , though environmental factors such as may exacerbate them in susceptible individuals. These defects manifest as malformed or absent acrosomes, impairing the sperm's ability to undergo the necessary for fertilization. Key types include globozoospermia, characterized by round-headed spermatozoa lacking an acrosome; macrocephalic sperm syndrome, featuring enlarged sperm heads with oversized or dysmorphic acrosomes; and partial acrosomelessness, where a subset of sperm exhibit incomplete or fragmented acrosomal caps. Globozoospermia results from homozygous deletions in the DPY19L2 gene, which encodes a protein essential for anchoring the inner acrosomal membrane to the , thereby blocking acrosome formation and sperm head elongation. Similarly, macrocephalic sperm defects stem from mutations in the AURKC gene, which encodes aurora kinase C, a regulator of and condensation, leading to abnormally large acrosomes and multiflagellar tails in affected sperm. Partial acrosomelessness often involves incomplete fusion of acrosomal vesicles, resulting in sperm with partially detached or vestigial acrosomes. Recent studies have identified additional genes, such as TMC7, where mutations cause acrosome biogenesis defects and . The genetic basis of these defects frequently involves autosomal recessive inheritance, with increasing risk in affected populations due to the prevalence of such disorders. Mutations in SPATA16, which encodes a spermatogenesis-specific protein involved in acrosomal vesicle trafficking, lead to vacuolized or fragmented acrosomes in partial globozoospermia cases. Likewise, variants in PICK1, encoding a protein that interacts with Golgi-associated PDZ and coiled-coil motif-containing protein (GOPC) to facilitate acrosome assembly, cause and acrosomal disintegration during early . DPY19L2 deletions account for 50-70% of globozoospermia cases and follow autosomal recessive patterns, often via nonallelic between low-copy repeats flanking the gene. AURKC mutations, such as the recurrent c.144delC frameshift, are also recessively inherited and predominate in certain ethnic groups, like North Africans, resulting in near-100% abnormal morphology. Diagnosis relies on advanced imaging and biochemical assays to identify acrosomal anomalies. Transmission electron microscopy reveals characteristic features, such as detached acrosomes, fragmented membranes, or complete absence in globozoospermic sperm, alongside nuclear envelope disruptions. Acrosin activity assays, which measure the proteolytic enzyme's levels as a proxy for acrosomal integrity, typically show reduced activity below 10% of normal values in affected individuals, correlating with fertilization failure. These tools distinguish acrosome defects from other teratozoospermias by highlighting specific ultrastructural pathologies not evident in standard light microscopy. As of 2025, updated guidelines recommend enhanced acrosomal evaluation in sperm morphology assessments. Acrosome defects contribute to approximately 0.1-1% of cases, with globozoospermia incidence under 0.1% and macrozoospermia under 1% among infertile men. Animal models, particularly mice, recapitulate human phenotypes; for instance, Dpy19l2-null mice exhibit round-headed, acrosomeless with halted head elongation, while Pick1-deficient mice display vacuolized acrosomes and globozoospermia-like , validating the genetic mechanisms observed in humans. These defects profoundly impact fertility by preventing penetration.

Implications for Fertility

Failures in the significantly contribute to male factor , accounting for up to 29% of cases among patients with and normal parameters. In conditions like globozoospermia, characterized by round-headed lacking a functional acrosome, conventional fertilization (IVF) fertilization rates are markedly reduced, often below 20%, due to the inability of to penetrate the . Male factor overall represents 20-30% of infertility cases, with acrosomal dysfunction playing a key role in impaired -egg interaction and reduced IVF success. Diagnostic approaches for acrosomal issues include assays to evaluate the , such as Pisum sativum agglutinin (PSA) lectin binding, which assesses acrosomal integrity via or staining. Semen analysis incorporates evaluation of acrosomal status using stains like Spermac or Coomassie blue to quantify intact acrosomes, helping identify defects in sperm function. For genetic forms like globozoospermia, screening for DPY19L2 deletions is recommended, as these account for the majority (50-80%) of cases and confirm hereditary acrosome biogenesis failure. Intracytoplasmic sperm injection (ICSI) circumvents requirements by directly injecting into the , achieving fertilization rates of 70-80% in many male factor cases, though outcomes are poorer in severe acrosome defects without additional interventions. In globozoospermia, ICSI alone yields low fertilization (around 24%), and risks or activation failure, often necessitating assisted oocyte activation (AOA) with calcium ionophores to improve rates to 50-60%. Emerging therapies, such as gene editing targeting acrosome-related genes, remain in preclinical stages and show promise in animal models for restoring function. Epidemiological data indicate higher incidence of acrosomal defects in consanguineous populations, likely due to autosomal recessive . Environmental factors, including endocrine disruptors like and , are implicated in impairment and contribute to by altering signaling and .

Research and Evolution

Current Research

Recent advancements in imaging technologies have provided deeper insights into acrosomal dynamics during sperm capacitation and exocytosis. Super-resolution microscopy techniques, such as 3D structured illumination microscopy, have revealed nanoscale changes in acrosomal vesicle transport and actin cytoskeleton remodeling, surpassing traditional light microscopy limitations. Genome-wide CRISPR-Cas9 screens have identified novel regulators of spermatogenesis integrity. In vivo screening targeting testicular germ cells has uncovered genes influencing spermatogenesis, with disruptions leading to reduced fertility in mouse models. Similarly, CRISPR-based functional studies have pinpointed ion channel proteins like TMC7 as critical for acrosome formation, where knockout results in disorganized proacrosomal granules and infertility. Post-2020 research has elucidated the regulatory roles of microRNAs in acrosomal processes. For instance, miR-34c and miR-449 are upregulated in high-fertility during , promoting by targeting genes involved in vesicle trafficking and enzyme release; their absence in models impairs acrosomal integrity and fertilization success. Proteomic analyses from 2023 have further explored glycan interactions, identifying species-specific glycan-binding proteins on that facilitate acrosomal penetration, with implications for evolutionary adaptations in . Additionally, stem cell-derived spermatids serve as models for defects, allowing recapitulation of developmental pathways. Ongoing efforts are supported by major funding initiatives and collaborations. Proteomic analyses have mapped 885 proteins in acrosomes, revealing biomarkers for fertilization competence and guiding therapeutic targets for . International consortia, including the European Society of and (ESHRE), prioritize evaluation, diagnosis, function, , , and prognostic biomarkers of success in assisted reproductive technologies.

Evolutionary Aspects

The acrosome, a specialized essential for sperm-egg interaction, exhibits origins traceable to ancient metazoan lineages, with acrosome-like structures evident in such as sea urchins, where the perforatorium forms as an extension following the to facilitate egg penetration. This structure likely evolved around 500 million years ago, coinciding with the emergence of in early bilaterians during the period, as adaptations for penetrating protective egg coats became necessary in more complex reproductive strategies. Across phylogeny, the acrosome demonstrates remarkable conservation as a Golgi-derived, lysosome-related in most bilaterians, serving a core function in hydrolytic release for fusion. It is ubiquitous in vertebrates and many with but absent or highly reduced in certain non-bilaterian groups and some , such as nematodes, where alternative penetration mechanisms suffice. Mammals exhibit innovations in acrosome architecture, including a compartmentalized housing a diverse array of hydrolytic enzymes—such as acrosin and —optimized for breaching the , a multilayered envelope absent in many non-mammalian species. Adaptations in acrosome morphology reflect species-specific reproductive demands, with notable size variations observed among ; for instance, larger acrosomes in species like and correlate with thicker zonae pellucidae (up to 15–20 μm), enhancing enzymatic dispersion for penetration in these taxa compared to the relatively smaller acrosomes in like mice. In some species, such as , the acrosome is vestigial and minimal, reflecting reduced reliance on enzymatic due to direct entry without a zona-like barrier. Evolutionary pressures, particularly sexual selection via sperm competition, have favored robust acrosomes by accelerating the evolution of associated genes, promoting structural integrity and enzymatic efficiency to outcompete rival sperm in multi-male mating scenarios. Fossil evidence supports this antiquity, with sperm impressions in 100-million-year-old Cretaceous amber from Myanmar revealing preserved acrosomal structures, including pointed lateral acrosomes in ostracod spermatodesmids, indicating that complex acrosome morphology predates mammalian diversification.

References

  1. https://pmc.ncbi.nlm.nih.gov/articles/PMC6759486/
  2. https://pmc.ncbi.nlm.nih.gov/articles/PMC3271650/
  3. https://oertx.highered.texas.gov/courseware/lesson/1838/student/?section=8
  4. https://www.ncbi.nlm.nih.gov/books/NBK10033/
  5. https://pmc.ncbi.nlm.nih.gov/articles/PMC6109296/
  6. https://academic.oup.com/molehr/article/24/12/567/5095621
  7. https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/pdf/10.1002/jemt.10315
  8. https://www.sciencedirect.com/topics/medicine-and-dentistry/spermatozoon-head
  9. https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1439-0272.1975.tb01247.x
  10. https://pmc.ncbi.nlm.nih.gov/articles/PMC11186999/
  11. https://www.sciencedirect.com/topics/medicine-and-dentistry/acrosome
  12. https://pmc.ncbi.nlm.nih.gov/articles/PMC5112175/
  13. https://academic.oup.com/icb/article-pdf/15/3/523/6005709/15-3-523.pdf
  14. https://link.springer.com/article/10.1007/BF00220142
  15. https://www.fertstert.org/article/S0015-0282%2801%2901755-1/fulltext
  16. https://doi.org/10.1093/biolre/ioab117
  17. https://pubmed.ncbi.nlm.nih.gov/1903927/
  18. https://pubmed.ncbi.nlm.nih.gov/9508094/
  19. https://pubmed.ncbi.nlm.nih.gov/8838007/
  20. https://www.jbc.org/article/S0021-9258(19)44411-6/fulltext
  21. https://www.pnas.org/doi/10.1073/pnas.0506825102
  22. https://pmc.ncbi.nlm.nih.gov/articles/PMC2120058/
  23. https://pubmed.ncbi.nlm.nih.gov/8269854/
  24. https://pmc.ncbi.nlm.nih.gov/articles/PMC8790511/
  25. https://pubmed.ncbi.nlm.nih.gov/22946049/
  26. https://pmc.ncbi.nlm.nih.gov/articles/PMC4198580/
  27. https://pmc.ncbi.nlm.nih.gov/articles/PMC10947329/
  28. https://pubmed.ncbi.nlm.nih.gov/11225983/
  29. https://onlinelibrary.wiley.com/doi/10.1002/mrd.23431
  30. https://anatomypubs.onlinelibrary.wiley.com/doi/pdf/10.1002/aja.1001740307
  31. https://www.imrpress.com/journal/FBL/1/4/10.2741/A119/pdf
  32. https://pmc.ncbi.nlm.nih.gov/articles/PMC2112130/
  33. https://www.sciencedirect.com/science/article/abs/pii/0014482773902735
  34. https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.682790/full
  35. https://www.jbc.org/article/S0021-9258%2819%2969307-5/pdf
  36. https://www.mdpi.com/2218-273X/14/6/685
  37. https://onlinelibrary.wiley.com/doi/10.1111/andr.12320
  38. https://www.sciencedirect.com/science/article/abs/pii/S0303720703004593
  39. https://doi.org/10.3389/fcell.2019.00195
  40. https://doi.org/10.1242/jcs.218958
  41. https://pmc.ncbi.nlm.nih.gov/articles/PMC9295470/
  42. https://pmc.ncbi.nlm.nih.gov/articles/PMC5029953/
  43. https://pmc.ncbi.nlm.nih.gov/articles/PMC4076372/
  44. https://pmc.ncbi.nlm.nih.gov/articles/PMC3064341/
  45. https://pmc.ncbi.nlm.nih.gov/articles/PMC3228701/
  46. https://pmc.ncbi.nlm.nih.gov/articles/PMC10138380/
  47. https://pmc.ncbi.nlm.nih.gov/articles/PMC6078053/
  48. https://pmc.ncbi.nlm.nih.gov/articles/PMC3998876/
  49. https://elifesciences.org/articles/95888
  50. https://onlinelibrary.wiley.com/doi/10.1111/andr.70134
  51. https://pubmed.ncbi.nlm.nih.gov/12524067/
  52. https://wjmh.org/DOIx.php?id=10.5534/wjmh.220020
  53. https://www.mdpi.com/2077-0383/9/12/3899
  54. https://pubmed.ncbi.nlm.nih.gov/2393693/
  55. https://pubmed.ncbi.nlm.nih.gov/34253371/
  56. https://pmc.ncbi.nlm.nih.gov/articles/PMC9826911/
  57. https://www.sciencedirect.com/science/article/pii/S0143416013001449
  58. https://www.fertstert.org/article/S0015-0282%2819%2931446-3/fulltext
  59. https://www.mdpi.com/2073-4425/13/6/1000
  60. https://academic.oup.com/humrep/article/16/7/1365/693383
  61. https://www.embopress.org/doi/10.15252/embr.201438869
  62. https://pmc.ncbi.nlm.nih.gov/articles/PMC6240301/
  63. https://www.sciencedirect.com/science/article/pii/S2666979X24000375
  64. https://pmc.ncbi.nlm.nih.gov/articles/PMC10967381/
  65. https://pubmed.ncbi.nlm.nih.gov/37271105/
  66. https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2020.00432/full
  67. https://pubmed.ncbi.nlm.nih.gov/36805822/
  68. https://www.eshre.eu/specialty-groups/special-interest-groups/andrology
  69. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/acrosome
  70. https://www.nature.com/articles/s41467-022-34609-7
  71. https://pmc.ncbi.nlm.nih.gov/articles/PMC8812575/
  72. https://journals.biologists.com/dev/article/133/24/4871/52931/Sperm-plasma-membrane-breakdown-during-Drosophila
  73. https://pmc.ncbi.nlm.nih.gov/articles/PMC7007544/
  74. https://royalsocietypublishing.org/doi/10.1098/rsob.150076
  75. https://pubmed.ncbi.nlm.nih.gov/20080865/
  76. https://pubs.geoscienceworld.org/sgf/bsgf/article/191/1/31/592447/Synopsis-of-rare-fossil-animal-spermatozoa-in
Add your contribution
Related Hubs
User Avatar
No comments yet.