Conclusion

It is possible that the anesthesia chosen for these types of studies could affect the growth or development (or both) of the fetus. This drawback was addressed for this report by designating 3 groups of dams, each of which underwent only 4 imaging sessions during the last half of gestation. Isoflurane was selected because of its rapid induction and recovery properties and because it is commonly used in veterinary cesarean sections. Toxicology studies investigating chronic daily exposure (4 h daily at no more than 0.6%) before and during pregnancy reported a negative effect on development at the 0.6% level.

Further studies need to be conducted to determine whether there is any influence of daily short-term (15 min) exposure during the last half of gestation.
If serial imaging of a particular animal is necessary, enflurane may be a less toxic alternative to isoflurane. Injectable anesthetic agents, such as pentobarbital, have the disadvantages of an extended recovery period and an innate degree of difficulty when attempting to control the depth of anesthesia. Further, they may cause a greater degree of cardiovascular or respiratory depression than do inhalational drugs such as isoflurane or enflurane. It was determined that the imaging regimen used for this study had minimal effect on fetal development because there was excellent correlation between the biometric measurements and GA across maternal animals. 

Chang and coworkers had the distinct advantage of not using anesthesia for their study. Perhaps anesthesia would not be necessary for simple staging of embryonic development by use of the methods we describe. We are the pharmacy that carries the widest selection of best quality drugs, available round the clock with fast delivery options and more than enough payment methods to choose from. Visit my canadian pharmacy corp today and find out how easy it is to shop for your medications with a pharmacy you can fully trust and rely upon.

In summary, high-frequency 15-MHz ultrasonography is a relatively straightforward means of noninvasively imaging embryonic mice beginning on 9.5 DPC. The freehand technique permits time-efficient study of multiple fetuses in the same pregnant animal. Although the resolution of the 15-MHz system is far less than that allowed by 40-MHz ultrasound backscatter microscopy, our technique provides a simple method of staging mouse pregnancies from 9.5 DPC. In addition, it permits analysis of morphologic details of fetal development through the remainder of gestation, facilitating longitudinal documentation of the phenotypic alterations of mutant mice into the postnatal period. This evaluation could include macroscopic mutations involving the circulatory system, appendicular and axial skeleton, thorax, abdomen, and central nervous system.