{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,21]],"date-time":"2026-02-21T11:36:20Z","timestamp":1771673780212,"version":"3.50.1"},"reference-count":53,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2021,9,6]],"date-time":"2021-09-06T00:00:00Z","timestamp":1630886400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>The presence of empty zona pellucida (EZP) in oocytes following oocyte retrieval (OR) during an in vitro fertilization (IVF) cycle presents a major clinical and laboratory challenge in assisted reproduction. It has been attributed to several factors such as the ovarian stimulation protocol employed, the damaging of the follicles during oocyte retrieval (OR) mainly through the high aspiration pressure, during the denudation technique, and the degeneration of oolemma within the zona pellucida (ZP) through apoptosis. The role of ZP is pivotal from the early stages of follicular development up to the preimplantation embryo development and embryo hatching. Polymorphisms or alterations on the genes that encode ZP proteins may contribute to EZP. We present a critical review of the published literature hitherto on EZP and available options when encountered with the phenomenon of EZP. Concerning the former, we found that there is rare data on this phenomenon that merits documentation. The latter includes technical, genetic, and pathophysiological perspectives, along with specific treatment options. In conclusion, we identify the lack of a definitive management proposal for couples presenting with this phenomenon, we underline the need for an algorithm, and indicate the questions raised that point towards our goal for a strategy when addressing a previous finding of EZP.<\/jats:p>","DOI":"10.3390\/ijerph18179409","type":"journal-article","created":{"date-parts":[[2021,9,6]],"date-time":"2021-09-06T21:47:38Z","timestamp":1630964858000},"page":"9409","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Empty Zona Pellucida Only Case: A Critical Review of the Literature"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0850-6623","authenticated-orcid":false,"given":"Charalampos","family":"Siristatidis","sequence":"first","affiliation":[{"name":"Assisted Reproduction Unit, Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"},{"name":"Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Despoina","family":"Tzanakaki","sequence":"additional","affiliation":[{"name":"Assisted Reproduction Unit, Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1000-9100","authenticated-orcid":false,"given":"Mara","family":"Simopoulou","sequence":"additional","affiliation":[{"name":"Assisted Reproduction Unit, Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christina","family":"Vaitsopoulou","sequence":"additional","affiliation":[{"name":"Assisted Reproduction Unit, Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Petroula","family":"Tsioulou","sequence":"additional","affiliation":[{"name":"Assisted Reproduction Unit, Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sofoklis","family":"Stavros","sequence":"additional","affiliation":[{"name":"Molecular Biology of Reproduction Unit and Recurrent Abortions Unit, Assisted Reproduction Unit, First Department of Obstetrics and Gynecology, Alexandra Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8331-2402","authenticated-orcid":false,"given":"Michail","family":"Papapanou","sequence":"additional","affiliation":[{"name":"Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peter","family":"Drakakis","sequence":"additional","affiliation":[{"name":"Molecular Biology of Reproduction Unit and Recurrent Abortions Unit, Assisted Reproduction Unit, First Department of Obstetrics and Gynecology, Alexandra Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Panagiotis","family":"Bakas","sequence":"additional","affiliation":[{"name":"Assisted Reproduction Unit, Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"},{"name":"Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nikolaos","family":"Vlahos","sequence":"additional","affiliation":[{"name":"Assisted Reproduction Unit, Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"},{"name":"Second Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1093\/humupd\/dmx040","article-title":"Acquisition of oocyte competence to develop as an embryo: Integrated nuclear and cytoplasmic events","volume":"24","author":"Conti","year":"2018","journal-title":"Hum. Reprod. Update"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1002\/rmb2.12071","article-title":"Characterization of oocyte retrieval cycles with empty zona pellucida","volume":"17","author":"Oride","year":"2018","journal-title":"Reprod. Med. Biol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1007\/s00439-019-01990-1","article-title":"Novel mutations in ZP1, ZP2, and ZP3 cause female infertility due to abnormal zona pellucida formation","volume":"138","author":"Zhou","year":"2019","journal-title":"Hum. Genet."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1596","DOI":"10.1093\/humrep\/deh811","article-title":"High magnitude of light retardation by the zona pellucida is associated with conception cycles","volume":"20","author":"Shen","year":"2005","journal-title":"Hum. Reprod."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1095\/biolreprod.114.117911","article-title":"Unresolved Questions Concerning Mammalian Sperm Acrosomal Exocytosis","volume":"90","author":"Buffone","year":"2014","journal-title":"Biol. Reprod."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4892","DOI":"10.1073\/pnas.1018202108","article-title":"Most fertilizing mouse spermatozoa begin their acrosome reaction before contact with the Zona Pellucida during in vitro fertilization","volume":"108","author":"Jin","year":"2011","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2669","DOI":"10.1016\/j.fertnstert.2011.01.168","article-title":"Sequence variations in human ZP genes as potential modifiers of zona pellucida architecture","volume":"95","author":"Lakkakorpi","year":"2011","journal-title":"Fertil. Steril."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"8557","DOI":"10.1111\/jcmm.15482","article-title":"Heterozygous mutations in ZP1 and ZP3 cause formation disorder of ZP and female infertility in human","volume":"24","author":"Cao","year":"2020","journal-title":"J. Cell. Mol. Med."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"341","DOI":"10.3109\/09513590.2011.631632","article-title":"Does empty zona pellucida indicate poor ovarian response on intra cytoplasmic sperm injection cycles?","volume":"28","author":"Cinar","year":"2012","journal-title":"Gynecol. Endocrinol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1001","DOI":"10.1016\/0093-691X(96)00028-3","article-title":"Effects of aspiration vacuum and needle diameter on cumulus oocyte complex morphology and developmental capacity of bovine oocytes","volume":"45","author":"Bols","year":"1996","journal-title":"Theriogenology"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/s13048-020-00708-6","article-title":"Degenerated oocyte in the cohort adversely affects IVF outcome","volume":"13","author":"Atzmon","year":"2020","journal-title":"J. Ovarian Res."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Lazzaroni-Tealdi, E., Barad, D.H., Albertini, D.F., Yu, Y., Kushnir, V.A., Russell, H., Wu, Y.-G., and Gleicher, N. (2015). Oocyte scoring enhances embryo-scoring in predicting pregnancy chances with IVF where it counts most. PLoS ONE, 10.","DOI":"10.1371\/journal.pone.0143632"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1267","DOI":"10.1093\/humrep\/12.6.1267","article-title":"Oocyte morphology predicts outcome of intracytoplasmic sperm injection","volume":"12","author":"Serhal","year":"1997","journal-title":"Hum. Reprod."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1750","DOI":"10.1093\/humrep\/12.8.1750","article-title":"Intracytoplasmic sperm injection: Correlation of oocyte grade based on polar body, perivitelline space and cytoplasmic inclusions with fertilization rate and embryo quality","volume":"12","author":"Xia","year":"1997","journal-title":"Hum. Reprod."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1016\/bs.ctdb.2018.01.001","article-title":"The human egg\u2019s zona pellucida","volume":"130","author":"Gupta","year":"2018","journal-title":"Curr. Top. Dev. Biol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1580","DOI":"10.1093\/humrep\/deh301","article-title":"Four zona pellucida glycoproteins are expressed in the human","volume":"19","author":"Conner","year":"2004","journal-title":"Hum. Reprod."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1007\/s10815-013-0141-8","article-title":"Are zona pellucida genes involved in recurrent oocyte lysis observed during in vitro fertilization?","volume":"31","author":"Lemerle","year":"2014","journal-title":"J. Assist. Reprod. Genet."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2151","DOI":"10.1007\/s10815-020-01855-x","article-title":"Novel biallelic loss-of-function variants in ZP1 identified in an infertile female with empty follicle syndrome","volume":"37","author":"Liu","year":"2020","journal-title":"J. Assist. Reprod. Genet."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1220","DOI":"10.1056\/NEJMoa1308851","article-title":"Mutant ZP1 in familial infertility","volume":"370","author":"Huang","year":"2014","journal-title":"N. Engl. J. Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1098\/rspb.1997.0046","article-title":"Mutant female mice carrying a single mZP3 allele produce eggs with a thin Zona Pellucida, but reproduce normally","volume":"264","author":"Wassarman","year":"1997","journal-title":"Proc. R. Soc. Lond. Ser. B Biol. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"394","DOI":"10.1093\/humrep\/dem373","article-title":"Detection of zona pellucida proteins during human folliculogenesis","volume":"23","author":"Gook","year":"2008","journal-title":"Hum. Reprod."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1016\/j.ajhg.2017.08.001","article-title":"A recurrent missense mutation in ZP3 causes empty follicle syndrome and female infertility","volume":"101","author":"Chen","year":"2017","journal-title":"Am. J. Hum. Genet."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"E59","DOI":"10.1038\/35055178","article-title":"A profile of fertilization in mammals","volume":"3","author":"Wassarman","year":"2001","journal-title":"Nat. Cell Biol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1148","DOI":"10.1093\/humrep\/deh835","article-title":"Cracking the egg: Increased complexity in the zona pellucida","volume":"20","author":"Conner","year":"2005","journal-title":"Hum. Reprod."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"90","DOI":"10.1016\/j.jri.2014.08.006","article-title":"Role of Zona Pellucida glycoproteins during fertilization in humans","volume":"108","author":"Gupta","year":"2015","journal-title":"J. Reprod. Immunol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"431","DOI":"10.1038\/s41436-018-0064-y","article-title":"ZP2 pathogenic variants cause in vitro fertilization failure and female infertility","volume":"21","author":"Dai","year":"2019","journal-title":"Genet. Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1007\/s10815-020-01995-0","article-title":"A novel mutation in ZP3 causes empty follicle syndrome and abnormal Zona Pellucida formation","volume":"38","author":"Zhang","year":"2021","journal-title":"J. Assist. Reprod. Genet."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2853","DOI":"10.1007\/s10815-020-01926-z","article-title":"Novel mutations in ZP1 and ZP2 cause primary infertility due to empty follicle syndrome and abnormal zona pellucida","volume":"37","author":"Luo","year":"2020","journal-title":"J. Assist. Reprod. Genet."},{"key":"ref_29","unstructured":"(2021, May 24). GeneCards: The Human Gene Database. Available online: https:\/\/www.genecards.org\/."},{"key":"ref_30","unstructured":"(2021, May 24). Female Infertility Due to Zona Pellucida Defect. Available online: https:\/\/www.malacards.org\/card\/female_infertility_due_to_zona_pellucida_defect."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1017\/S0967199413000403","article-title":"Embryological, clinical and ultrastructural study of human oocytes presenting indented zona pellucida","volume":"23","author":"Sousa","year":"2015","journal-title":"Zygote"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"653","DOI":"10.1038\/nature07599","article-title":"Crystal structure of the ZP-N domain of ZP3 reveals the core fold of animal egg coats","volume":"456","author":"Han","year":"2008","journal-title":"Nature"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1530\/rep.0.1230023","article-title":"Survival factors regulating ovarian apoptosis--dependence on follicle differentiation","volume":"123","author":"Markstrom","year":"2002","journal-title":"Reproduction"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"E40","DOI":"10.2527\/2004.8213_supplE40x","article-title":"Ovarian follicular growth and atresia: The relationship between cell proliferation and survival","volume":"82","author":"Quirk","year":"2004","journal-title":"J. Anim. Sci."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"511","DOI":"10.1016\/S0015-0282(01)03006-0","article-title":"Apoptosis in human cumulus cells in relation to zona pellucida thickness variation, maturation stage, and cleavage of the corresponding oocyte after intracytoplasmic sperm injection","volume":"77","author":"Gabrielsen","year":"2002","journal-title":"Fertil. Steril."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1016\/j.fertnstert.2007.07.1312","article-title":"Empty follicle syndrome: The reality of a controversial syndrome, a systematic review","volume":"90","author":"Stevenson","year":"2008","journal-title":"Fertil. Steril."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"367505","DOI":"10.1155\/2010\/367505","article-title":"Immature Oocytes in \u201cApparent Empty Follicle Syndrome\u201d: A Case Report","volume":"2010","author":"Vutyavanich","year":"2010","journal-title":"Case Rep. Med."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"640","DOI":"10.1016\/S1472-6483(10)60477-4","article-title":"Apoptosis, Reactive Oxygen Species and Follicular Anti-M\u00fcllerian Hormone in Natural versus Stimulated Cycles","volume":"16","author":"Jancar","year":"2008","journal-title":"Reprod. Biomed. Online"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Shi, W., Xu, B., Wu, L.-M., Jin, R.-T., Luan, H.-B., Luo, L.-H., Zhu, Q., Johansson, L., Liu, Y.-S., and Tong, X.-H. (2014). Oocytes with a dark zona pellucida demonstrate lower fertilization, implantation and clinical pregnancy rates in IVF\/ICSI cycles. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0089409"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1007\/s10815-008-9217-2","article-title":"Timing and duration of use of GnRH antagonist down-regulation for IVF\/ICSI cycles have no impact on oocyte quality or pregnancy outcomes","volume":"25","author":"Detti","year":"2008","journal-title":"J. Assist. Reprod. Genet."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1016\/j.theriogenology.2009.08.007","article-title":"Oocyte quality and estradiol supplementation affect in vitro maturation success in the white-tailed deer (Odocoileus virginianus)","volume":"73","author":"Siriaroonrat","year":"2010","journal-title":"Theriogenology"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2301","DOI":"10.1210\/en.2006-1265","article-title":"Increased oocyte degeneration and follicular atresia during the estrous cycle in anti-Mullerian hormone null mice","volume":"148","author":"Visser","year":"2007","journal-title":"Endocrinology"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1093\/humupd\/2.1.77","article-title":"Aspiration of oocytes for in-vitro fertilization","volume":"2","author":"Horne","year":"1996","journal-title":"Hum. Reprod. Update"},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Veeck, L.L. (1999). An Atlas of Human Gametes and Conceptuses: An Illustrated Reference for Assisted Reproductive Technology, CC Press. [1st ed.].","DOI":"10.1201\/b14639"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1016\/j.fertnstert.2017.12.010","article-title":"Exome and genome sequencing in reproductive medicine","volume":"109","author":"Normand","year":"2018","journal-title":"Fertil. Steril."},{"key":"ref_46","first-page":"308","article-title":"MicroRNAs miR-30b, miR-30d, and miR-494 regulate human endometrial receptivity","volume":"20","author":"Esteban","year":"2014","journal-title":"Reprod. Sci."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Siristatidis, C., Stavros, S., Drakeley, A., Bettocchi, S., Pouliakis, A., Drakakis, P., Papapanou, M., and Vlahos, N. (2021). Omics and Artificial Intelligence to Improve In Vitro Fertilization (IVF) Success: A Proposed Protocol. Diagnostics, 11.","DOI":"10.3390\/diagnostics11050743"},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Ouni, E., Vertommen, D., and Amorim, C.A. (2019). The Human Ovary and Future of Fertility Assessment in the Post-Genome Era. Int. J. Mol. Sci., 20.","DOI":"10.3390\/ijms20174209"},{"key":"ref_49","first-page":"1117","article-title":"Reactive oxygen species in the follicular fluid of subfertile women undergoing in vitro fertilization: A short narrative review","volume":"36","author":"Askoxylaki","year":"2013","journal-title":"J. Endocrinol. Investig."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"959","DOI":"10.1007\/s10815-015-0489-z","article-title":"E-selectin, resistin and reactive oxygen species levels in GnRH-agonist and-antagonist protocols in IVF\/ICSI: A prospective cohort study","volume":"32","author":"Siristatidis","year":"2015","journal-title":"J. Assist. Reprod. Genet."},{"key":"ref_51","first-page":"149","article-title":"The effect of reactive oxygen species on embryo quality in IVF","volume":"30","author":"Siristatidis","year":"2016","journal-title":"In Vivo"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1016\/S1472-6483(10)61174-1","article-title":"Oxidative Stress and Its Implications in Female Infertility\u2014A Clinician\u2019s Perspective","volume":"11","author":"Agarwal","year":"2005","journal-title":"Reprod. Biomed. Online"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/s12958-018-0391-5","article-title":"A Novel and Compact Review on the Role of Oxidative Stress in Female Reproduction","volume":"16","author":"Lu","year":"2018","journal-title":"Reprod. Biol. Endocrinol."}],"container-title":["International Journal of Environmental Research and Public Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1660-4601\/18\/17\/9409\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:57:29Z","timestamp":1760165849000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1660-4601\/18\/17\/9409"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,9,6]]},"references-count":53,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2021,9]]}},"alternative-id":["ijerph18179409"],"URL":"https:\/\/doi.org\/10.3390\/ijerph18179409","relation":{},"ISSN":["1660-4601"],"issn-type":[{"value":"1660-4601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,9,6]]}}}