Zona pellucida
Introduction
(Latin, zona pellucida = transparent zone) A specialized extracellular matrix surrounding the developing oocyte (egg, ovum) within each follicle within the ovary. This thick matrix is thought to be formed by secretions from the oocyte and the follicle granulosa cells and consists of three types of zona pellucida glycoproteins ZP1, ZP2 and ZP3 which have different roles in fertilization.
Following fertilization, the zona pellucida also surrounds the blastocyst during the first week of development, from which it "hatches".
The zona pellucida has a role in fertilization, sperm binding, preventing polyspermy, blastocyst development and preventing premature implantation (ectopic pregnancy).
Links: Carnegie stage 1 | Carnegie stage 3 | Science Lecture - Cell Division and Fertilization
Original page links: Week 1 - Fertilization | Week 1 - Oogenesis |
Some Recent Findings
- Zona pellucida glycoprotein-1 binds to spermatozoa and induces acrosomal exocytosis[1] "These studies revealed for the first time that in humans ZP1, in addition to ZP3 and ZP4, binds to capacitated spermatozoa and induces acrosomal exocytosis."
Zona Pellucida Glycoproteins
These glycoproteins share several common structural features
- N-terminal hydrophobic signal peptide sequence
- potential N- and O-linked glycosylation sites
- a C-terminal hydrophobic transmembrane-like domain (TMD)
- a potential consensus proprotein convertase (furin) cleavage site (CFCS) upstream of TMD,
- "ZP domain"
Terms
acrosome reaction
The chemical change within the spermatozoa following binding to the zona pellucida, that leads to the release of acrosomal enzymatic contents. These enzymes degrade the zona pellucida and allow a spermatozoa to penetrate an oocyte.
granulosa cell
A specific cell type that proliferates in association with the oocyte within the developing follicles of the ovary. These cells form the follicle stratum granulosa and are also given specific names based upon their position within the follicle. In the antral follicle, membrana granulosa sits on the follicular basal lamina and lines the antrum as a stratified epithelium. The cumulus oophorus is a column of granulosa cells that attaches the oocyte to the follicle wall. The corona radiata are the granulosa cells that directly surround the oocyte, and are released along with it at ovulation. Following ovulation the corona radiata provide physical protection to the oocyte and granulosa cells within the ovulating follicle contribute to corpus luteum.
References
- ↑ <pubmed>20504872</pubmed>
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Cite this page: Hill, M.A. (2024, June 2) Embryology Zona pellucida. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Zona_pellucida
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
