TITLE:
Termination of Organogenesis as Intrinsic Constraint on Animal Development and Evolution: A Theory
AUTHORS:
Zi-Jian Cai
KEYWORDS:
Organogenesis, Induction, Termination, Cancer, Intrinsic Constraint, Organ Regeneration, Evolution, Recapitulation
JOURNAL NAME:
Open Access Library Journal,
Vol.2 No.6,
June
25,
2015
ABSTRACT: In this article, it is pointed out with integrative analysis that organogenesis
manifests limitation in time and possession of termination, while infinite cell
proliferation called as cancer and tumor is lethal. Besides, it is reversely demonstrated
from a few notable constant outgrowing skin derivatives that termination is
required for organogenesis inside the animal. Accordingly, it is suggested that
the requirement for organogenetic termination would be the new intrinsic
constraint for animal development and heredity. In further, it is suggested
from comparative analysis that this new intrinsic constraint would not
influence the temporal and spatial reorganization of morphogenesis, but place restrictions
on alteration of organogenetic mechanisms themselves. Especially, it is pointed
out that addition of new induction mechanism or elimination of termination mechanism
would usually cause endless organogenesis and lethality, subjecting to
restriction by the intrinsic constraint, while addition of new termination
mechanism or elimination of induction mechanism not be affected by the
intrinsic constraint, occurring more frequently in evolution. In accordance, it
is identified this intrinsic constraint as the pertaining cause for frequent
occurrence of developmental parallelism and terminal addition in animal
evolution as recapitulation. In this article, it is also provided with some
animal models to demonstrate the evolution of organogenetic termination as key
developmental control, such as the hair and nail in humans, the sexual dimorphism
in mammary glands, the epidermal scale in reptiles, the tail metamorphosis in
amphibians, and the variation in limb digits in vertebrates.