Correspondence on: A Hyaluronic Acid-Rich Node and Duct System in Which Pluripotent Adult Stem Cells Circulate.

The origin of the wide spread node and duct system described by Rai et al. remains a mystery. The explanation came when another study on yolk sack hemopoiesis was compared with the "primo vascular system".

Morphogens Reveal the Appearance and Functions of lncRNAs.

During the first meiotic division, the entire genetic information from DNA is transcribed into mRNPs and stored in the ovoplasm in the form of mRNP particles. The 39 human nuclear HOX proteins bind to thousands of mRNAs transcribed repeatedly by lampbrush chromosomes. HOX proteins suppress processing and translation.

Stem cells in light of a new concept for cell differentiation.

My concept of cell differentiation involves genetic information from DNA being transcribed into mRNA proteins-morphogenes (mRNAs+ homeodomain proteins)-and stored in the ovoplasm as maternal inheritance, or cytoplasmic genetic memory. Feedback mechanism(s) allow these morphogenes to selectively unlock new genes, regulating the development of the embryo. The blastomeres and the embryonic pluripotent cells of the inner cell mass of early (5 day) blastocysts are loaded with morphogenes which hamper the production of cell lines and are responsible for the formation of embryoid bodies in vitro and teratomas in vivo.

Stem cells: shibboleths of development, part II: Toward a functional definition.

Our previous discourse on stem cell characteristics led to the conclusion that the qualities deemed essential for a cell to be considered a "stem cell" are neither firmly established nor universally accepted, and this we accept as editorial policy. In that study, self-renewal, asymmetric division, phenotypic markers, and other attributes touted as being indicative of cells being stem cells were critically questioned as fundamental to the definition of a stem cell, leading us to seek a functional definition instead. Here, we offer further considerations, and elaborate on the characteristics that diverse investigators feel are essential for a cell to function as a stem cell, either in development or body maintenance.

The origin and development of the immune system with a view to stem cell therapy.

Careful study of the phylogeny and ontogeny of the three components of the immune system reveals that the macrophage, lymphatic, and hematopoietic systems originate independently of each other. Chronologically, the most ancient is the macrophage system, which arises in the coelomic cavity as mesenchymal ameboid cells having the properties to recognize self from non-self and to ingest foreign particles. The lymphatic system later develops from the endoderm of pharyngeal pouches, where the thymic anlage differentiates.