Embryo, mouse induction

Trichloroethane did not induce unscheduled DNA synthesis in rat primary hepatocytes. It showed inconclusive evidence of gene mutation at the tk locus in mouse lymphoma L5178Y cells in the presence of an exogenous metabolic activation system. Results for induction of sister chromatid exchanges were also inconclusive. 1,1,1-Trichloroethane increased the frequency of chromosomal aberrations in Chinese hamster ovary cell cultures and induced morphological transformation in BALB/c 3T3 and in Fischer rat and virally-enhanced Syrian hamster embryo cells in vitro. 

Interferon induction in normal and leukemic lymphocyte cultures with tilorone has been observed50. The interferon response observed in normal lymphocyte cultures appeared to be correlated with the toxic effect of tilorone. The effect observed in leukemic cultures required higher concentrations of tilorone, but, similarly, appeared to be related to cell viability. Tilorone has been reported to stimulate production of interferon by itself in mouse embryo fibroblasts and, in combination with poly rl poly rC/DEAE-dextran in mouse L929 cells51. Human foreskin fibroblasts were not stimulated. The degree of synergism between tilorone and the nucleotide-dextran complex was proportional to the concentrations of tilorone and poly rl/poly rC and was influenced by the times of addition of the compounds relative to each other. 

Davidson GE, Dawson GWP. 1977. Induction of somatic mutations in mouse embryos by benzo[a7 pyrene. Arch Toxicol 38 99-103. 

Fahrig, R. (1975). A mammaUan spot test induction of genetic alterations in pigment cells of mouse embryos with x-rays and chemical mutagens. Mol Gen Genet 138, 309-314. 

Lane M, Gardner DK. 1994. Increase in postimplantation development of cultured mouse embryos by amino acids and induction of fetal retardation and exencephaly by ammonium ions. J Reprod Fertil 102(2) 305-312. 

Sonic hedgehog is not only sufficient, but also is required for the correct differentiation of ventral cell types in the neural tube. Targeted disruption or deletion of the Sonic hedgehog gene in mice [73] and humans [74] leads to defects in the maintenance of the notochord and establishment of the floor plate, with subsequent development of severe malformations of forebrain and cranium characteristic of human holoprosencephaly. Thus, failure of the induction of the optic stalk and other cells in the forebrain of Sonic hedgehog null mouse embryos produces holoprosencephaly and cyclopia [73]. 

In vitro studies have indicated that devil s claw caused contractions of the uterus. The authors of the study noted that this activity was consistent with traditional use for induction or acceleration of labor, or for expulsion of retained placentas (Mahomed and Ojewole 2006). Another in vitro study indicated that some mouse embryos incubated in a solution containing devil s claw had misshapen tails but were otherwise normal (Yokoyama et al. 2005). 

When heterokaryons are formed between animal cells the nuclei in the same cytoplasm undergo synchronous initiation of DNA synthesis (Harris and Watkins, 1965) similar synchrony is observed in binucleate cells occurring in mouse embryo cultures (Church, 1967). DNA synthesis has been examined in multinucleate HeLa cells formed by fusion between cells in different phases of the life cycle (Rao and Johnson, 1970). There was a rapid induction of DNA synthesis in G1 phase nuclei following the fusion of G1 and S phase cells. When S phase cells were fused with G2 phase cells, no induction of DNA synthesis was observed in G2 phase nuclei and, no matter what the ratio of G2 S nuclei in the fused cell, the S phase nuclei continued DNA synthesis. 

Moditication of nuclear proteins by poly(ADP-ribose) has been implicated as an essential step in the differentiation of a number of different systems. However, in some systems a transient rise of poly(ADP-ribose) as a prerequisite of differentiation was deduced from experiments with inhibitors [e.g. mesodermal chick limb cells (1), myoblasts (2) HL 60 cells to macrophages (3) and lymphocytes (4)]. In others, a transient decrease of poly(ADP-ribose) polymerase activity was thought to be required for the induction of differentiation, as inhibitors of poly(ADP-ribosyl)ation were able to replace the inducers [e.g. erythroid differentiation of Friend leukemia cells (5), HL 60 cells to granulocytes (6), murine embryo carcinoma cells (7) and mouse manunary gland differentiation (8)]. 

Activation of Hematopoiesis and Vasculogenesis in the Mouse Embryo Induction and Reprogramming of Ectodermal Cell Fate by Signals from Primitive Endoderm... 

In nearly all vertebrate animals, embryonic blood development begins during gastrulation and results from the induction of extraembryonic mesoderm to form hematopoietic tissue. In the mouse, these events are initiated at around 6.5 days post coitum (p.c.) and lead to the formation of the yolk sac, a bilaminar membrane composed of adjacent mesodermal and primitive endodermal cell layers (reviewed in ref. 3). The yolk sac is an extraembryonic tissue which surrounds the entire embryo. Though it will not contribute cells directly to the fully formed animal, its fimction is essential to normal development (reviewed in refs. 3,6). 

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