Sexual differences in the development of plasma thyroxine levels in the embryo and young chick]

Plasma thyroxine (T4) levels were separately ascertained in male and female embryo and young chicken from the 12th day of incubation till the 4th day after hatching by the thyroxine binding globulin technique. In both sexes, plasma T4 reach a peak the 20th day of incubation, but values are significantly higher in females. A sharp decrease occurred thereafter, plasma T4 tending toward adult values the 4th day after hatching.     

Development of the hypothalamic-hypophysial-gonadotrophic activities in fetal rats

Pituitary responsiveness to LHRH and anti-LHRH serum was investigated in fetal rats aged 18.5-22.5 days. Synthetic LHRH injection in utero into fetuses brought about a remarkable depletion of pituitary-LH with a corresponding increase of serum-LH on day 18.5. On the contrary, anit-LHRH serum administration to day-20.5 fetuses caused a significant augmentation of pituitary-LH 1 day later. These data indicate that LH-gonadotrophs respond to LHRH even on day 18.5, and that endogenous LHRH begins to affect LH gonadotrophs on day 20.5.     

More on the need for circadian,circaseptan and circannual optimization of cyclosporine therapy

Summary Cyclosporine chronotherapy of pancreas-allotransplanted rats revealed, beyond a circadian stage-dependence of equal daily doses, further gain in graft function from doses varying from day to day with an about 7-day periodicity, the first highest dose being given on the 3rd or 5th day after surgery.     

More on the need for circadian, circaseptan and circannual optimization of cyclosporine therapy

Cyclosporine chronotherapy of pancreas-allotransplanted rats revealed, beyond a circadian stage-dependence of equal daily doses, further gain in graft function from doses varying from day to day with an about 7-day periodicity, the first highest dose being given on the 3rd or 5th day after surgery.     

High altitude influence on the level and turn-over time of cardiac norepinephrine in rats

Summary In rats exposed to an altitude, of 2,900 meters the level of endogenous cardiac norepinephrine decreases after the 5th day of exposure. The turner-over time of the amine proceeds in 3 steps which are probablyrelated to periods of stress and adaptation: initial increase, important decrease from the 5th day and return to a normal value from the 12 th day.     

Effect of glucagon administration on serum calcium and inorganic phosphorus in the freshwater mud eel,Amphipnous cuchia

Summary Glucagon injection inAmphipnous cuchia evokes a decreased level of serum calcium on day 1 which progresses till day 3. This response declines after day 5. The serum inorganic phosphorus level does not show any significant change.     

A daily rhythm in hCG binding to ovarian follicles of the cyclic hamster

On each day of the estrous cycle hCG binding to follicle increased from 09.00 to 21.00 h; then hCG binding was static until 09.00 h of the next day. FSH binding did not exhibit rhythmicity. This pattern of hCG binding may be related to the pulsing of LH on each cycle day.     

Changes in brush-border enzyme activities of intestinal epithelial cells isolated from the villus-crypt axis during the early phase of alloxan diabetes in rats

The sucrase activity in enterocytes isolated from the villus crypt axis was found to increase in all regions of the villus from day 2 after induction of diabetes, and the increase continued until day 4. In contrast, alkaline phosphatase activity increased mainly in the apical one-third of the villus-crypt column, and the increase occurred abruptly on day 4 with increase in food intake.     

Changes in brush-border enzyme activities of intestinal epithelial cells isolated from the villus-crypt axis during the early phase of alloxan diabetes in rats

Summary The sucrase activity in enterocytes isolated from the villus crypt axis was found to increase in all regions of the villus from day 2 after induction of diabetes, and the increase continued until day 4. In contrast, alkaline phosphatase activity increased mainly in the apical one-third of the villus-crypt column, and the increase occurred abruptly on day 4 with increase in food intake.     

Development of the hypothalamic-hypophysial-gonadotrophic activities in fetal rats

Summary Pituitary responsiveness to LHRH and anti-LHRH serum was investigated in fetal rats aged 18.5–22.5 days. Synthetic LHRH injection in utero into fetuses brought about a remarkable depletion of pituitary-LH with a corresponding increase of serum-LH on day 18.5. On the contrary, anti-LHRH serum administration to day-20.5 fetuses caused a significant augmentation of pituitary-LH 1 day later. These data indicate that LH-gonadotrophs respond to LHRH even on day 18.5, and that endogenous LHRH begins to affect LH-gonadotrophs on day 20.5.This work was supported by a grant from Ministry of Education, Science and Culture, Japan. The exert technical assistance of Mr Yoshihito Okamura is gratefully acknowledged.     

Effect of low dose of 70 kVp X-rays on the intrauterine development of mice

Pregnant Swiss albino mice were exposed to low doses of X-rays (approximately 9 mGy) in the range used for diagnostic exposure, on day 3.5 of gestation (preimplantation period), day 6.5 (early organogenesis period) or day 11.5 (late organogenesis period). The fetuses were examined on the 18th day of gestation. Exposure at 3.5 days post coitus (d.p.c.) resulted in a significant increase in prenatal mortality, and an increased incidence of retarded fetuses was observed after exposure at 3.5 and 6.5 d.p.c. The major effect of exposure at 11.5 d.p.c. was a significant decrease in the fetal head size and brain weight.     

Effect of progesterone on male and female sex behavior induced by steroid hormones in adult ovariectomized ewes]

Ovariectomized adult Ewes daily treated with I/M injections of testosterone propionate (10 mg/day) or oestradiol benzoate (200 microgram/day) show male-like sexual behaviour and simultaneously a permanent female receptivity. Additional daily treatment with 100 mg of progresterone results in a rapid decrease in male sexual responses both when Ewes are treated with testosterone and with oestradiol. No effect is observed on the female receptivity. Cyproterone acetate (100 mg/day) given to Ewes in addition to daily injection of testosterone propionate (10 mg/day) has effects similar to those of progesterone. These results show that progesterone has antiandrogen and antioestrogen properties and that this hormone administered at high doses is able to inhibit male activity.     

Expression of multidrug resistance (mdr) gene(s) in primary lymphoid organs of chicken immune system during embryonic development

The presence of a multidrug resistance (MDR) related protein, P-170, in normal and pathological lymphoid cells has been described. The present report evaluates the expression of themdr 1 gene by using the reverse Polymerase Chain Reaction (PCR) on cells obtained from the thymus and bursa of chicken embryos starting from day 12 until hatching. Results show that the thymic cells are positive from day 12 to the end of the observation period. In contrast,mdr mRNA was detected in the bursa from day 14 to day 17 of embryonic life. Possible relationships between the expression ofmdr and the development of T and B lymphocytes are discussed.     

Befunde aus der Frühentwicklung des Rattenkeimes als Beitrag zur Rhythmik der Entwicklung

Summary On the fourth day of development of the rat embryo all of the stages are found from the two-cell stage to the blastocele stage even among embryos from the same litter. On the seventh day, they all show egg-cylinder stages without exception. The time interval between cleavages from the second to the sixth day of development is not constant and, in fact, varies over a wide range, even among embryos from the same litter.     

Comparison of estradiol benzoate and dihydrotestosterone propionate with testosterone propionate on the induction of male-like sexual behavior in female sheep ovariectomized as adults]

Daily I/M injections of 200 microgram of oestradiol benzoate induce in female Sheep, ovariectomized as adults, male-like sexual reactions similar to what is obtained with 10 mg testosterone propionate per day. Simultaneously, a permanent female sexual receptivity is observed. Oestradiol benzoate at the dose of 20 microgram/day, and dihydrotestosterone propionate (10 mg/day) are both totally ineffective. The result support the hypothesis of the necessity of the aromatization of testosterone for the action on sexual behaviour.     

The effects of actinomycin D and chloramphenicol on the rat preimplantation embryos

Summary Actinomycin D and chloramphenicol, injected in the rat on day 3 or 4 of gestation, induce embryolethality and embryotoxicity. These effects are revealed on day 5 of pregnancy by reduced number of blastocysts and by decrease of mean blastomeres number.     

The effects of actinomycin D and chloramphenicol on the rat preimplantation embryos

Actinomycin D and chloramphenicol, injected in the rat on day 3 or 4 of gestation, induce embryolethality and embryotoxicity. These effects are revealed on day 5 of pregnancy by reduced number of blastocysts and by decrease of mean blastomeres number.     

Effect of low dose of 70 kVp X-rays on the intrauterine development of mice

Summary Pregnant Swiss albino mice were exposed to low doses of X-rays (9 mGy) in the range used for diagnostic exposure, on day 3.5 of gestation (preimplantation period), day 6.5 (early organogenesis period) or day 11.5 (late organogenesis period). The fetuses were examined on the 18th day of gestation. Exposure at 3.5 days post coitus (d.p.c.) resulted in a significant increase in prenatal mortality, and an increased incidence of retarded fetuses was observed after exposure at 3.5 and 6.5 d.p.c. The major effect of exposure at 11.5 d.p.c. was a significant decrease in the fetal head size and brain weight.     

In vivo effect of sodium valproate on mouse liver

The in vivo effect of sodium valproate (SV) on the activity of uridine diphosphate glucuronosyltransferase (UDP-GT) and hepatotoxicity in the mouse liver was studied. Mice were injected intraperitoneally (IP) with SV at doses varying from 50 to 800 mg/kg per day, for six consecutive days (dose-response group) or at a standard dose of 300 mg/g per day for 2-10 days (time-response group), whereas the controls were injected with normal saline. Valproic acid levels had a positive correlation to the dose (P < 0.001) and duration of drug administration (P = 0.006). A gradual increase in UDP-GT activity was observed in doses of up to approximately 400 mg/kg per day, whereas in higher doses the enzyme activity gradually decreased. The time course of UDP-GT activity at the standard dose of 300 mg/kg per day increased progressively, with a maximum up to the sixth day and then had a gradual reduction. Hepatic necrosis (which was unrelated to the dose or the duration of drug administration) was found in 13% of the SV-treated animals and in none of the controls. We conclude that at an optimal dose (300-400 mg/kg per day) and at a time course of 6 days, SV causes liver UDP-GT induction, whereas in higher doses and longer duration of administration, UDP-GT activity is gradually reduced. SV also causes hepatotoxicity unrelated to dose and time course.     

Variation in the specific activity of intestinal DNA in Alytes obstetricians larvae (Amphibia, Anura) treated with thyroxine]

Treatment by thyroxine modified the specific activity of intestianl DNA in premetamorphic Alytes tadpoles. The activity decreased up to the 3rd day, and showed afterwards a peak which culminates on the 9th day. These results have been discussed in comparison with previous radioautographic observations.