An alternative germ layer origin of thyroid neuroendocrine cells cannot be excluded.
This may reflect the male germ cell origin of these tumours, which is proposed to differ only in differentiation status between the SSE and TGCT (Oosterhuis and Looijenga, 2005).
With the aim of assessing whether the oncogenic cooperation between lgl mutation and dMyc protein could be conserved in other Drosophila tissues, we investigated lgl-/ clonal behaviour in the ovarian follicular epithelium, a monolayered adult tissue of somatic origin that surrounds the germ line of the egg chamber.
The results support the notion that both base substitutions within genes and gene duplication are associated with gene expression breadth and that the nature of duplication (WGD or SSD) differs substantially depending on the germ-layer origin of the tissue.
These authors suggested that the persistence of instability into the germ line of unexposed offspring of irradiated mice could be responsible of mosaicism in germ cells, a well-known mechanism in the origin of human genetic disorders [ 150].
Nonetheless, the expression of GATA in the sponge inner cell layer suggests a shared ancestry with the eumetazoan endomesoderm, and that the ancestral role of GATA in specifying internalised cells may antedate the origin of germ layers.
They also now found the idea on the origin of germ cells from bone marrow untenable, suggesting that bone marrow cells function primarily by reactivating host oogenesis impaired by chemotherapy [ 95].
Here, then, is the origin, the germ, the source of the sectarian wars that are tearing the region apart.
For those cancers of germ cell origin, the expression of ES-cell-specific pluripotency factors, such as Oct4 and Nanog, is likely to be functionally relevant [ 59].
Mutations in both alleles of the RB1 gene are required for the development of this neoplasm [ 4], and, depending on the germ-line or somatic origin of the defect, a heritable or sporadic form can be distinguished.
