Developmental changes in epithelial transport characteristics of preimplantation rabbit blastocysts.

Abstract

1. Transepithelial sucrose and urea permeability coefficients were measured in different‐aged preimplantation rabbit blastocysts. Sucrose permeability remained constant from 4 to 6 days after fertilization (approximately 1 X 10(‐8) cm s‐1), but thereafter increased. Urea permeability was very low throughout this period (5 X 10(‐7) cm s‐1) but a phloretin‐sensitive component to urea influx appeared between day 6 and day 7 post coitum (p.c.). 2. Glucose uptake was small (0.2‐0.5 nmol cm‐2 s‐1 and independent of external sodium throughout the preimplantation period. 3. Methionine uptake was 10 times greater than glucose uptake, and was strongly dependent upon the presence of external sodium in 5 and 6 day p.c. blastocysts. The sodium dependence of methionine uptake was lost by the seventh day after fertilization. 4. The transepithelial electrical resistance was always less than 35 omega cm2 in 4 day p.c. blastocysts, and averaged 1758 omega cm2 in 6 day p.c. blastocysts. 5. The transepithelial influx of 140 La averaged 0.46 +/‐ 0.11 nmol cm‐2 h‐1 (n = 6) in 4 day p.c. blastocysts. The 5 day p.c. embryos, on the other hand were impermeable to lanthanum (n = 10). 6. These results indicate that the epithelium of the preimplantation rabbit blastocyst undergoes dramatic changes in transport characteristics with development. The blastocyst can be characterized as a ‘leaky’ transporting epithelium during the early blastocyst period, and as a ‘tight’ epithelium during the mid to late stages of the preimplantation period.

Synthesis of Na+/K+ ATPase by the preimplantation rabbit blastocyst

“…This is in agreement with previous reports that free methionine concentration is very low and comparable in rabbit blastocyst tissue (Petzoldt era/., 1973;Miller & Schultz, 1987), blastocoelic fluid (Lesinski et al, 1967;Jaszczak et al, 1972) and uterine fluid (Jaszczak et al, 1972;Miller & Schultz, 1987). During radiolabelling, methionine is readily transported into blastomeres by Na +-dependent and Na +-independent mechanisms (Benos, 1981b;Bell et al, 1986) and swamps out the comparatively small endogenous methionine pool. We demonstrate that free methionine rapidly equilibrates between the uterine and blastocoelic compartments which support the work of Miller & Schultz (1987 (Brinster et al, 1976(Brinster et al, , 1979 (Lo & Edelman, 1976;Cook et al, 1985).…”

“…Benos (1981b) (Boardman et al, 1974;Pollack et al, 1981;Edelman et al, 1985) is modulated by hormonal factors (Jorgenssen, 1972;Geheb et al, 1983;Paccolat et al, 1987;McDonough et al, 1988 (Daniel, 1964), and a decrease in overall oxidative metabolism (Benos &Balaban, 1980,1983. Other physiological studies (Benos, 1981a, b;Benos & Biggers, 1981;Benos etal, 1985) …”

“…For example, net transtrophectodermalNa+ influx increases 10-fold during this period (Borland etal,\ 976). Ouabain, a specific inhibitor of Na+/K + ATPase, has been shown to inhibit both the accumulation of blastocyst fluid (Biggers et al, 1978) and > 50% of net trans-trophectodermal Na+ transport in preimplantation rabbit blastocysts (Benos, 1981b).…”

Hexose transport in preimplantation rabbit blastocysts

“…The flux rate of organic molecules via paracellular pathways has been found to be low (Robinson et ai, 1989), and this is undoubtedly a conse¬ quence of the tight junctions formed between trophectodermal cells (Hasting & Enders, 1975;Beños, 1981). Therefore, regulation of transcellular solute transport systems (i.e.…”

Preimplantation Mouse Embryo Selection Guided by Light-Induced Dielectrophoresis

“…Changes in morphology have been correlated to significant changes in the electrical properties of 1-cell to blastocyst stage embryos of various species[14], [34], [35]. This scaling of electrical properties can result in large fluctuations in the DEP response of pre-implantation stage embryos and, therefore, provide a quantitative means by which to assess embryo morphology and/or health ( Fig.…”