Biomedical subjects

E M Deuchar

Publications and source records attributed to E M Deuchar.

At least 19 recordsLinked to original sources

PubMed1978

Effects of streptozotocin on early rat embryos grown in culture.

Addition of 1 mg/ml streptozotocin to serum in which 10-day rat embryos are cultured reduces their growth and viability. There is therefore a risk that administration of this drug to pregnant animals to induce diabetes could also have direct, deleterious effects on the embryos.

Animals↗

PubMed1977

Embryonic malformations in rats, resulting from maternal diabetes: preliminary observations.

Diabetes mellitus was induced in female Wistar rats by injections of either alloxan or streptozotocin, and their embryos were found to have significantly higher incidences (7.5%) of brain and heart abnormalities (non-closure of neural folds, and deformities of heart chambers) at mid-gestation than controls (2.2%). There were also increased numbers of resorptions (25% in diabetic animals: 7.2% in controls). Both drugs produced similar abnormalities. External and X-ray examination of 488 foetuses from streptozotocin-treated animals at 20 days showed eight cases of exomphalos, two cases of micrognathia with tongue protrusion, and 34 cases of incomplete sacral ossification. This last deformity occurred also in foetuses of mildly diabetic animals, and has been seen occasionally in infants of human diabetic mothers. Other evidence suggests that skeletal deformities may be due to hyperinsulinism in the foetuses of diabetic mothers. Even a mild or pre-diabetic condition may set the foetus at risk.

Abnormalities, Multiple↗

PubMed1975

Regeneration of the tail bud in Xenopus embryos.

In an attempt to solve some aspect of the long-standing controversy about the regenerative ability of appendages in vertebrate embryos, the tail bud of Xenopus laevis embryos has beenamputated at stage sranging from St. 26 to St. 32 and its ability to regenerate duringa culture period of 2-3 days has been studied. At amputation stages 26-28,the tail bud consisted only undifferentialted mesoderm and ectoderm, but at stage 32 it had afully differentiated neural tube, a vaculotaed notochord and segmented somites. A total of 137amputations at differnt stages gace consistent results: a tail formed in all the operated larvacand it had normal, well-developed axial tissues in most cases. The relatively few cases with abnormal tail struture were stunted, oedematour larvae with defects in the trunk region as well. It is concluded from these experiments that cells near the original tail budare able to differentiate into tialbud tissues and to replace the amputated regoin, even at these late embryoic stages. The implications of these findings for comparative studies on regeneration in vertebrates are discussed.

Amputation, Surgical↗

PubMed1975

Reconstitutive ability of axial tissue in early rat embryos after operations and culture in vitro.

Longitudinal incisions have been made in the axis of 10-day-old rat embryos (post-neurula stage with 5-10 pairs of somites) at mid-trunk levels, dividing the axis into right and left halves. The embryos have then been cultured in vitro by New's method and their ability to reconstitute tissues in each half has been studied. After 20 h culture at 37 degrees C, there was no longer any external sign of the division of the axis. Histological studies showed that in nearly all cases, however, the neural tube was duplicated in the operated region. The two neural tubes lay in close contact in the midline, and ventral to them the gut was single. Apart from four cases in which the gut roof was slightly broadened and forked, all other tissues were normal. The reconstitutive ability of the neural and gut tissue has been compared with that of amphibian and avian embryos, as observed in 'twinning' experiments by other workers. The apparent delay in axial rotation in the operated rat embryos, as compared with controls, is attributed to the inability of the two separated halves of the somite series to co-ordinate their contractions. Further details of the rotation process in operated embryos will be the subject of a future study.

Animals↗

PubMed1975