%0 Journal Article
%T The Hypothetic Nutrient Constraint to Continuously Maintain as Gradient from Gastrula to Postnatal Development: An Important Mechanism for Recapitulation
%A Zi-Jian Cai
%J European Journal of Theoretical and Applied Sciences
%P 668-675
%D 2024
%R 10.59324/ejtas.2024.2(5).61
%X It was suggested by Cai a theory that the nutrient gradient differentiate the cellular living states to form the three germ layers of animal embryonic gastrula differential developing to three different subsequent fates, with the endoderm manifesting cellular living states in nutritious condition and forming the epithelium of digestive and respiratory system; the ectoderm manifesting cellular living states of nutrient dependence and environmental effects, and giving rise to the nervous and epithelial tissues; the mesoderm lying between them and forming the muscle and adipose. In parallel, it was also complied with the regulation of nutrients on various cultured stem cells. In this article, to account for these phenomena, it is extended this theory and suggested that there be a constraint maintaining such nutrient gradient from gastrula to postnatal development continuously, due to the animals necessarily to deal with the nutritional transport and environmental effects being the same across all developmental stages after gastrula, for most animals before the appearance of rigid eggshell in evolution. It is the nutrient constraint forming gradient at gastrula that coordinates the development of all animals into fixed nutrient gradient as the most primitive animal of gastrula, recapitulating the developmental program at gastrula. In contrast, it is unnecessary for all animals universally to deal with nutritional transport before gastrula, generating evolutionary diversity in early embryonic stages before gastrula, as well as violations to Haeckel¡¯s recapitulation.
%K Gastrula
%K Trilaminar Germ Layers
%K Nutrient
%K Recapitulation
%U https://ejtas.com/index.php/journal/article/view/1202