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.

Protein, RNA, DNA, RN‐ase in different sections of the oviduct during the egg‐formation cycle

“…The protein concentration of the magnum was lower at 6 and 12 hrs than immediately after oviposition. This is the result of secreting thick albumen for the egg white as the yolk passes through the magnum, only in the part of the magnum directly in contact with the yolk (LAUGIER and BRARD 1977). These results support the data presented by ED-WARDS et al (1976) which show that from 4 hrs after oviposition there is an apparently linear rise in the levels of the egg-white proteins in the magnum.…”

Effects of Estradiol Benzoate and Progesterone on Egg White Proteins Secretion

“…According to Aitken and Johnston (1963) these cells represent a maximally stimulated form of dark grained cells. The observation of Laugier and Brard (1977) regarding the distribution of light and dark granules during the ovulatory cycle agree with the conclusions of these authors. The latter have shown, moreover, that the light granules are more rapidly excreted than the dark ones, 48.9 ± 1.1* (27.4 ± 1.5)a 2 52.7 ± 3.0* (38.7 ± 2.3)a 5.6 ± .9* (13.3 ± l.l)a 6.8 ± 1.4* (24.8 ± 1.4)a of which a few remain in the tubular gland cells after the passage of a yolk.…”

“…Secretion was more abundant when the introduction took place at the time of ovulation. It is at that moment, in effect, that the cellular concentration of egg white proteins in the magnum is at its maximum (Laugier and Brard, 1977) and albumen secretion should be the greatest.…”

“…Recently we have shown by biochemical and ultrastructural analyses that the secretion of albumen occurred only in the tubular gland cells of the magnum directly in contract with the developing egg and that the gland cell protein concentration was extremely variable during the ovulatory cycle in the quail (Laugier and Brard, 1977).…”