Pellucid zone


Definition of Pellucid zone
(Scientific name: Zona pellucida)

From the elephant glossary Section: reproduction





Relevant Literature about Pellucid zone
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The zona pellucida (plural zonae pellucidae, also egg coat or pellucid zone) is a glycoprotein layer surrounding the plasma membrane of mammalian oocytes. It is a vital constitutive part of the oocyte. The zona pellucida first appears in unilaminar primary oocytes. It is secreted by both the oocyte and the ovarian follicles. The zona pellucida is surrounded by the corona radiata. The corona is composed of cells that care for the egg when it is emitted from the ovary.


Mammalian zona pellucida (ZP) is composed of 3 to 4 glycoproteins, which plays an important role during fertilization. Mutations in the genes encoding zona proteins are reported in women with empty follicle syndrome, degenerated oocytes and those with an abnormal or no ZP further emphasizing their relevance during fertility. Immunization with either native or recombinant ZP glycoproteins/proteins leads to curtailment of fertility in various animal Species. Observed infertility is frequently associated with ovarian pathology characterized by follicular atresia and degenerative changes in ZP, which may be due to oophoritogenic T cell epitope(s) within ZP glycoproteins. To avoid ovarian dystrophy, B cell epitopes of ZP glycoproteins have been mapped by using bio-effective monoclonal antibodies. Immunization with the immunogens encompassing the mapped B cell epitopes by and large led to amelioration of follicular atresia. However, their use for human application will require more rigorous Research to establish their safety and reversibility of the contraceptive effect. Nonetheless, to minimize human-animal conflicts, ZP-based contraceptive vaccines have been used successfully in the population management of free-ranging animal Species such as feral horses, white-tailed deer and elephants.
Satish K Gupta, Zona pellucida glycoproteins



Concerted efforts to nurture elephant populations have resulted in elephant overpopulation in several areas, which in turn has led to damaging levels of browsing. As an alternative to Culling entire family Groups in order to control this damage, we have developed an immunocontraceptive vaccine from pig zona pellucida which safely and successfully controls free-roaming African elephants.

Immunocontraceptive vaccines cause the immune system to produce antibodies that prevent fertilization, without the side effects of hormonal Contraceptives. The vaccine antigens are the proteins of the zona pellucida, the clear protein coat surrounding mammalian eggs. The surface structures of the elephant zona pellucida are very similar to those of the pig zona pellucida.
R. A. Fayrer-Hosken, D. Grobler, J. J. Van Altena, H. J. Bertschinger & J. F. Kirkpatrick, Immunocontraception of African elephants



The vaccinated female elephants developed significant (P<0.05) titers to pZP over prevaccination levels. These levels persisted for 12 to 14 mo after the third vaccination. This preliminary evidence shows that the female elephant can develop significant serum antibody levels to pZP. These levels of antibodies are comparable to those required in horses for successful immunocontraception. Thus, porcine zona pellucida immunocontraception might be used to control elephant populations.

Contraceptive potential of the porcine zona pellucida vaccine in the African elephant (loxodonta africana)
R.A.Fayrer-Hosken1H.J.Bertschinger,.F.Kirkpatrick.Grobler.Lamberski.Honneyman.Ulrich, Contraceptive potential of the porcine zona pellucida vaccine in the African elephant (loxodonta africana)


Reference list Koehl, Dan, (2025). Pellucid zone. Elephant Encyclopedia, available online retrieved 20 September 2021 at https://www.elephant.se/index.php?id=238. (archived at the Wayback machine)

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Selected publications
  • Satish K Gupta, Zona pellucida glycoproteins: Relevance in fertility and development of contraceptive vaccines

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Categories glossary | reproduction

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