The total protein content and the protein fractions were determined in the blood serum and the cerebrospinal fluid (CSF) of chick embryos and foetuses between the 4th and 20th day of incubation and of 2-day-old chickens (by Lowry's method and by polyacrylamide gel electrophoresis respectively). The main results were the following: The total protein content of the CSF increased from 1.8 mg/ml on day 4 to 3.1 mg/ml on day 10. After a slight decrease to 2.6 mg/ml on day 12 no further changes were detected. In the blood serum the total protein content was 4.3 mg/ml on day 4 and 4.7 mg/ml on day 9. Beginning with day 10 it increased constantly to 23.2 mg/ml on day 2 after hatching (daily rate 1-1.2 mg/ml). It results that the "protein barrier" between blood and CSF begins to function after 10-12 days of incubation. Of the protein fractions determined, the light fraction I in the CSF represents 50 per cent of the similar blood serum fraction (on day 10). As to the heavy fractions XI-XIV, their concentration in the CSF represents, beginning with day 10, 51 per cent of the similar blood serum fraction (until the end of the period investigated). It results that the "protein barrier" has an active, selective character. Some comparative aspects with literature data are discussed.

Animals↗

PubMedDate not supplied

The effect of early hypoxy upon the development of rats and mice. II. Foetal effects.

The late, foetal effect of temporary hypoxy--performed by uterine vascular clamping--during the preimplantation period (day 2, 3 and 4 of pregnancy) was controlled in rats. The main detected effects were: lowering of the number of implantation sites and of the mean number of living foetuses; lowering of the mean foetal weight: increased percentage of resorptions and partial retardation of skeletal development. No structural anomalies were registered.

Animals↗

PubMedDate not supplied

There are no in vivo pulsations of mouse blastocysts.

An important event at the onset of the implantation process in mammals is the hatching of the blastocyst from the zona pellucida. Microcinematographic studies of in vitro preimplantation development in mice revealed the pulsatile activity of blastocysts before and during the hatching period. It is generally accepted--up to now--that the in vitro hatching is at least partially the result of repeated contractions and reexpansions of the blastocyst. The presence of pulsatile activity in vivo may confirm this hypothesis. Mouse blastocysts were obtained by a rapid flushing (5-10') from uterine horns on day 4 of pregnancy and the presence or absence of contracted blastocysts was noted. From 410 examined blastocysts only 3% were contracted as compared with the very frequent in vitro pulsations. This result suggests that in mice the in vivo pulsatile activity of blastocysts, practically, does not exist. The in vivo contractions are probably determined by the suboptimal culture conditions.

Animals↗