Changements biochimiques dans le magnum de caille au cours du cycle ovulatoire. Role des hormones stéroïdes endogènes

Abstract

As the developing egg passes along the magnum, more than 80% of the soluble proteins and ovalbumin are released in the lumen and the RNA per milligram of DNA decreases by 31%. This discharge of the secretory goblet cells occurs only in the part of the magnum directly in contact with the yolk. The formation of egg white proteins during the cycle is in two stages. First there is a short period following the release of albumen when the synthesis of ovalbumin is very rapid at the beginning and then decreases to a minimum 5 h after oviposition. Secondly, from 5 h after oviposition to the next discharge of the glandular cells, the concentration of ovalbumin per cell unit increases with a rate of synthesis (Sov) equal to 0.218(t – 7) + 1.119 (Sov, milligram per milligram of DNA; t, number of hours after oviposition). The qualitative analysis of the ovalbumin shows that it is the fraction of dephosphoovalbumin which is synthesized first. It is quickly transformed into diphospho- and triphosphoovalbumin. By surgical removal (4 h after oviposition) of the post ovulatory follicle (Fr) and the F1 follicle, which are responsible for the preovulatory peak of progesterone, or of F2, F3, and F4 follicles, which are responsible for the preovulatory peaks of estrogen and testosterone, a dramatic inhibition of the rate of egg-white protein synthesis is induced.