Kinetics of telencephalic neural cell proliferation during the fetal regeneration period following a single X-irradiation at the late organogenesis stage

Abstract

Summary.A sequential study of the acute effects of prenatal X-irradiation on telencephalic cell population dynamics was performed by combining a pathological evaluation with autoradiographic methods. This study confirmed that a dose of 0,95 Gy affects nearly all neuroblasts in the GI-, G2-, and M-stage lethally. Within ventricular cells staying in the S-phase at the time of X-irradiation, lethal effects are in the range between 50% and 75%. The surviving remainder of these neuroblasts is responsible for subsequent attempts for regeneration of the telencephalic roof. Two subpopulations of the surviving S-phase cells were observed: The first subpopulation which seems to be restricted to the rudiments of the ventricular zone shows a S/G2-blockade for 8-12 h after X-irradiation. Thereafter these cells start again with mitotic activity. The second subpopulation is morphologically manifested by the formation of heterotopic cell nests, i.e., so-called rosettes. These cells continue with an intense DNA-replication after the 12th h post irradiation and proceed to the mitosis stage only after about another 4 -8 h, i.e., the 16th to 20th hour following X-irradiation. These findings indicate the existence of two different pools of regenerative cells within the telencephalic roof, giving rise to either orthotopic or heterotopic growth processes after irradiation injury.

Kinetics of telencephalic neural cell proliferation during the fetal regeneration period following a single X-irradiation at the late organogenesis stage

“…The growth fraction is fairly constant on days 13 and 14 p.c. This was already described in detail in the previous report (Schmahl 1982a). 10), but sharply decreases to 0.6 at the lateral hemispheric wall district on day 17 p.c.…”

“…The keeping, mating, and X-irradiation of the pregnant mice on day 12 of gestation with a single close of 0.95 Gy has recently been described in detail (Schmahl 1982a). (Quastler and Sherman 1957) Pregnant mice, irradiated on day 12 of gestation received a single i.p.…”

“…In the foregoing study we characterized the morphological reactions at the telencephalic roof wall following immediately after single X-irradiation (0.95 Gy) on day 12 of gestation (Schmahl 1982a). Within 24 h two different reaction patterns of those ventricular zone cells which stay in the S-phase of the generation cycle and are not killed immediately by the irradiation, could be distinguished.…”

Sequence-dependent toxicity and small bowel mucosal injury in neonatal mice treated with low doses of 5-azacytidine and X-irradiation at the late organogenesis stage

“…Some years ago, we already referred to the validity of a teratological assay system for evaluating drug-radiation interactions (Schmahl 1979). Besides its practical importance in public health politics (UNSCEAR 1982), prenatal pathology also provides a good possibility of studying cell kinetic responses in an in vivo-model system (Schmahl 1982), since in rodents the early fetal cell populations of the different organs are almost homogeneous with approximately constant cycle times until day 14-15 of gestation (Kauffman 1968(Kauffman , 1975Schultze et al 1974). We therefore described a marked increase in neuropathological effects after combining a single azacytidine treatment with X-irradiation at an interval of two hours during intrauterine development (Schmahl 1979).…”

Radiation‐Induced Apoptosis and Developmental Disturbance of the Brain*

“…The initial histological damage produced by ionizing radiation and resulting in microcephaly is cell death of germinal cells in the primordial brain mantle ( Hicks et al, 1959;D'Agostino and Brizzee, 1966;Murakami 1968;Takeuchi et al, 1976;Takeuchi and Murakami, 1979;Schmahl, 1982). This was confirmed in human fetuses exposed to radium irradiation (Driscoll et al, 1963).…”