Understanding avian egg cuticle formation in the oviduct: a study of its origin and deposition

Understanding avian egg cuticle formation in the oviduct: a study of its origin and deposition

The cuticle is a unique invisible oviduct secretion that protects avian eggs from bacterial penetration through gas exchange pores. Despite its importance, experimental evidence is lacking for where, when, and what is responsible for its deposition. By using knowledge about the ovulatory cycle and o...

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Bibliographic Details
Published in:Biology of reproduction Vol. 97; no. 1; pp. 39 - 49
Main Authors: Wilson, Peter W, Suther, Ceara S, Bain, Maureen M, Icken, Wiebke, Jones, Anita, Quinlan-Pluck, Fiona, Olori, Victor, Gautron, Joël, Dunn, Ian C
Format: Journal Article
Language:English
Published: United States Society for the Study of Reproduction 01-07-2017
Oxford University Press
Society for the Study of Reproduction - Oxford Academic
Subjects:
Animals
Chickens - physiology
Egg Shell - physiology
Eggs
Female
Female Reproductive Tract
gonadotropin-releasing hormone
Life Sciences
oviduct
Oviducts - physiology
Oviposition
Ovulation
ovum
Ovum - physiology
uterus
vasopressin
gonadotropin-releasing hormone
oviduct
uterus
ovum
vasopressin
gonadotropin-releasing
hormone
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Summary:The cuticle is a unique invisible oviduct secretion that protects avian eggs from bacterial penetration through gas exchange pores. Despite its importance, experimental evidence is lacking for where, when, and what is responsible for its deposition. By using knowledge about the ovulatory cycle and oviposition, we have manipulated cuticle deposition to obtain evidence on these key points. Cuticle deposition was measured using staining and spectrophotometry. Experimental evidence supports the location of cuticle deposition to be the shell gland pouch (uterus), not the vagina, and the time of deposition to be within the final hour before oviposition. Oviposition induced by arginine vasotocin or prostaglandin, the penultimate and ultimate factors for the induction of oviposition, produces an egg with no cuticle; therefore, these factors are not responsible for cuticle secretion. Conversely, oviposition induced by GNRH, which mimics the normal events of ovulation and oviposition, results in a normal cuticle. There is no evidence that cuticle deposition differs at the end of a clutch and, therefore, there is no evidence that the ovulatory surge of progesterone affects cuticle deposition. Overall, the results demonstrate that the cuticle is a specific secretion and is not merely an extension of the organicmatrix of the shell. Cuticle deposition was found to be reduced by an environmental stressor, and there is no codependence of the deposition of pigment and cuticle. Defining the basic facts surrounding cuticle deposition will help reduce contamination of hen's eggs and increase understanding of the strategies birds use to protect their eggs. Summary Sentence The cuticle is an invisible but important defense against microbes entering avian eggs. Where and when in the oviduct it is deposited on the egg and what influences its deposition have been demonstrated in the paper.
Bibliography:Grant Support: This work was funded by Biotechnology and Biological Sciences Research Council (BBSRC), Lohmann Tierzucht, and Aviagen through the BBSRC LINK grant BB/K0070921/1 “Cute-Egg.” CSS was in receipt of a World's Poultry Science Association UK branch summer scholarship. The Roslin Institute is funded with a BBSRC institute strategic programme grant BB/J004316/1.
ISSN:0006-3363
1529-7268
DOI:10.1093/biolre/iox070