[Oocyte maturation in Xenopus laevis. The entry of progesterone is necessary for maturation]

In vitro progesterone-induced maturation of Xenope ovocyte was studied as a function of progesterone uptake and extracellular progesterone concentration. Maturation depends on the initial total amount of progesterone in incubation medium and does not depend on the extracellular hormonal concentration. This result strongly argues for an intracellular receptor site for progesterone.

[Influence of a juvenile hormone analog on ovarian function in parasectomized Labidura riparia (Insecta, Dermaptera) females]

The juvenile hormone analogue (methyl 3.7.11-trimethyl 11-chloro 2-dodecanoate), after administration at various doses on parsectomised female earwigs prevented the degeneration of follicular cells of ovaries and also induced a rapid vitellogenesis followed usually by an oviposition. However, the normal reproductive cycle and the parental care could not be restored in such treated female Insects.

Induction of maturation (meiosis) in small Xenopus laevis oocytes by injection of maturation promoting factor

Treatment of small-(stage III) or medium-sized (stage IV) Xenopus laevis oocytes with progesterone, human chorionic gonadotropin, or para-hydroxymercuriphenylsulfonate does not induce maturation. Only the full-grown oocytes (stage VI) undergo maturation when treated with either one of these three substances. In contrast, injection of maturation promoting factor into oocytes of stages III-VI invariably leads to chromosome condensation and germinal vesicle breakdown. No maturation spindle is found in oocytes smaller than 0.9 nm in diameter, and the nuclear sap does not mix with the cytoplasm in the smallest (0.45-0.55 mm in diameter) oocytes. In oocytes of 0.9 mm, maturation is identical to that of full-grown oocytes, except that the maturation spindle does not reach the cortex of the oocyte. Progesterone increases protein synthesis in medium-sized (0.8 mm in diameter) oocytes without inducing meiosis. It has little or no effect on protein synthesis in smaller oocytes.

[Meiosis: role of a histone kinase in the condensation of ovarian oocyte chromosomes of Xenopus laevis and Ambystoma mexicanum]

By injecting heterologous histone-kinase preparations into ovarian Axolotl oocytes, it has been possible to speed up the progesterone-induced process of chromosome condensation. Moreover, in some instances, this condensation and even complete maturation have been obtained after injection of protein kinase alone, thus in the absence of hormone stimulation. Two different histone kinase preparations have been used: one was prepared from ascites cell chromatin and the other from in vitro ovulated Xenopus oocytes.

[The effect of a juvenile hormone mimetic on the ovarian function of allatectomized females of Labidura riparia (Insecta, Dermaptera]

The methyl-3, 7, 11-trimethyl-11-chlorine-2-dodecanoate, a Juvenile Hormone analogue, used at different doses on allatectomised females of Labidura riparia, starts a vitellogenesis, a rapid disappearance of follicular degenerations and in some cases an intensive eggs laying. However, neither the normal reproductive cycle nor the parental comportment have been reconstituted.

[Modulation of 17-alpha-hydroxy-20 beta-dihydroprogesterone or gonadotropic extract activity on the in vitro intrafollicular maturation of rainbow trout (Salmo gairdnerii) oocytes by various steroids lacking maturing activity]

The efficiency of 17 alpha-hydroxy-20 beta-dihydroprogesterone (17 alpha-20 beta Pg) or of a Trout pituitary gonadotropic extract to induce intrafollicular maturation of trout oocytes can be modulated by some steroids which do not present any direct maturing action: gonadotropic extract efficiency is lowered by estradiol and estrone, and enhanced by testosteron. As these steroids do not present a significant effect on 17 alpha-20 beta Pg induced maturation, their site of action may be located in the follicular tissues. The corticosteroids, particularly cortisol and cortisone enhance the maturing efficiency of gonadotropin and stimulate much more strongly the efficiency of 17 alpha-20 beta Pg. This suggests a direct effect on oocyte sensitivity to 17 alpha-20 beta Pg.

Oogenesis in Xenopus laevis (Daudin). IV. Effects of gonadotropin, estrogen and starvation on endocytosis in developing oocytes

This study was designed to explore the relationship of estrogen, human chorionic gonadotropin (HCG), and food availability to endocytosis in developing oocytes. When estrogen alone is administered to an animal, large amounts of vitellogenin are synthesized by the liver and secreted into the circulatory system, where it accumulates. Under these conditions there is no evidence of endocytosis at the surface of the oocytes. Other studies have shown that following HCG injection into estrogen-treated animals, vitellogenin is removed from the circulation and the oocyte surface is highly contoured and displays endocytotic activity. Food deprivation has much the same effect on oocyte endocytosis as does estrogen. When animals are given HCG and subsequently starved for 20 days, developing oocytes show little endocytotic activity. We conclude that HCG acts to promote or stimulate endocytosis in developing oocytes while estrogen and/or starvation inhibits this process.

[Molting and vitellogenesis in Orchestia gammarella Pallas (crustacea amphipoda): study of the female-specific protein synthesis after ecdysterone administration (author's transl)]

Ecdysterone, administered to Orchestia gammarella females (200 mug/g), has no positive effect on the female-specific protein synthesis and vitellogenesis.

[Influence of chronic injections of aminazin on the oogenesis and development of the progeny of animals (white mice)]

When introduced repeatedly prior to the onset of pregnancy chlorpromazine in a dose of 16 mg/kg limits the progeny of albino mice. An important factor responsible for the reduction in the number of young mice in the litter is inhibition of oogenesis. A single injection of the same dose of chlorpromazine made at the end of gestation (18th day) against the background of its preliminary administration before the onset of pregnancy results in an interruption of the latter, or in a gravely disturbed post-natal development of some of the offsprings. The disturbances find their expression in a delayed growth and motor activity, incoordination of motions and are accompanied by changes in the tegument, diarrhea (form the moment of changing over to a mixed alimentation), in underdevelopment of the organs and of histological structures that are part of them.

Influence of concanavalin a on autolysis of gametes from Chlamydomonas reinhardii

The phytohemagglutinin concanavalin A inhibited zygote formation of Chlamydomonas reinhardii. 15--50 mug lectin/ml not only interfered with the mating reaction, but also with cell wall lysis of gametes and zoospores in a crude autolysin preparation gained from copulating gametes. Further, the structure of cell walls shed into the medium after autolysis in the course of the mating reaction and after lysis "from without" in the crude autolysin preparation was stabilized by Con A. Therefore, it must be assumed that the lectin inhibited zygote formation of C. reinhardii by interfering with autolysis of the cell walls of the gametes. Though Con A inhibited the lytic processes of C. reinhardii, an activation of the autolytic system in theta gametes by the lectin was found to compete with its inhibitory reaction. Con A induced autolysis of theta gametes was dependent on adherence of the cells by their flagella to the surface of the culture vessel or the liquid medium and did not occur in cultures stirred by rotation. The interferences of Con A with the autolytic serum of C. rienhardii were inhibited by methyl-alpha-D-mannopyrano-side and to a lesser degree by glucose, indicating that the carbohydrate binding sites of the lectin were involved in its reactions with the cells.

[The effect of an injection of synthetic juvenile hormone on Locusta migratoria L]

Hyalophora cecropia synthetic juvenile hormone (Demoute and al., 1973) is injected at doses of 50, 100 or 200 mug in 10 mul of pure peanut oil in fourth stadium of Locusta migratoria migratorioides. This synthetic juvenile hormone shows high chromatotropic, gonadotropic, and juvenilizing actions which are very similar to those of one pair of corpora allata of the species.