The hardening process of the egg chorion of the cod, Gadus morhua L., and lumpsucker, Cyclopterus lumpus L.

• Published in: Journal of Fish Biology
• Main Authors: Lönning, S., Kjörsvik, E., Davenport, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1984
• Subjects: Gadus morhua
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1984.tb04821.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1984.tb04821.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1984.tb04821.x

When transferred to sea water the chorion of cod and lumpsucker eggs harden, reaching a resistance of about 150 and 2000 g respectively. In sea water this hardening process is independent of fertilization. Studies of eggs kept in artificial sea water with various ionic compositions indicated, in the lumpsucker eggs, that a cortical reaction seems to be a prerequisite for the hardening process. Calcium is necessary for the reaction both in unfertilized and inseminated eggs, whereas hardening takes place in the absence of potassium, magnesium or sulphate. Addition of barium or strontium as a substitute for calcium only caused hardening in the presence of activating spermatozoa. Activating spermatozoa were also necessary for hardening of lumpsucker eggs kept in ovarian fluid, but such hardening only occurred if calcium and/or magnesium were added. The hardening of lumpsucker eggs was associated with profound changes in the thickness and surface appearance of the chorion.