https://www.cell.com/trends/neurosciences/pdf/0166-2236(93)90162-F.pdf

Neurotransmitters as growth regulatory signals: role of receptors and second messengers

Mechanisms, mechanics and function of epithelial-mesenchymal transitions in early development

V. Blastula formation . . . . . . . . . . . VI. Changes in shape of the blastula and the gastrula ectoderm . . . ( I ) Llorphopenetic models and their application. . . . . (2) Structural and biochemical basis for the differences in cell contact (3) Dynamic properties of the cell sheets . . . . , . VII. Arm formation . . . . . . . . . . . \-111. Morphogenesis of the mesenchyme, skeleton and archenteron . . ( I ) General features and morphogenetic models. . . . . (2) The primary mesenchyme and the basis of its pattern . . . (3) Development of the skeleton . . . . . . . (4) Gastrulation . . . . . . . . . . (j) The secondary mesenchyme. . . . . . . . (6) Pseudopodal activity, contact paralysis and contact inhibition . . , IX. Early morphogenesis of the archenteron after its invagination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . . X. Further morphogenesis of the archenteron and mouth formation . ( I ) Subdivision of the coelom and mouth formation . . . (2) Development of the peristaltic network around the oesophagus

Cellular movement and contact in sea urchin morphogenesis

Micromeres are isolated at the 16-cell stage from three species of Japanese sea urchins, Hemicentrotus pulcherrimus, Pseudocentrotus depressus , and Anthocidaris crassispina , and are cultured in sea water containing a small amount of horse serum. In all species used, isolated micromeres first divide unequally as they do in vivo. The pattern and number of the subsequent cleavages are also the same as in vivo, although they are not necessarily clear in all cases, since the border of the adjacent cells become invisible at each resting stage in some batches of embryos.

After cleavage, passing through the stage when the contours of the individual cell are obscure, decendants of the isolated micromeres form cell aggregates similar to the group of primary mesenchyme cells in a blastula. Within such aggregates, a spicular rudiment appears which develops either into a triradiate spicule as in normal gastrulae or into a rod. The triradiate spicule grows into a three-dimensional skeleton which is very similar to the normal pluteus skeleton, not only in its final shape and size including species-specific characters but in its developmental course and crystallographic nature. The rod, on the other hand, develops into either a one-dimensional or two-dimensional skeleton. These skeletons probably correspond to a part of the complete skeleton.

Spicule Formation by Isolated Micromeres of the Sea Urchin Embryo

Gastrulation is a fundamental phase of animal embryogenesis during which germ layers are specified, rearranged, and shaped into a body plan with organ rudiments. Gastrulation involves four evolutionarily conserved morphogenetic movements, each of which results in a specific morphologic transformation. During emboly, mesodermal and endodermal cells become internalized beneath the ectoderm. Epibolic movements spread and thin germ layers. Convergence movements narrow germ layers dorsoventrally, while concurrent extension movements elongate them anteroposteriorly. Each gastrulation movement can be achieved by single or multiple motile cell behaviors, including cell shape changes, directed migration, planar and radial intercalations, and cell divisions. Recent studies delineate cyclical and ratchet-like behaviors of the actomyosin cytoskeleton as a common mechanism underlying various gastrulation cell behaviors. Gastrulation movements are guided by differential cell adhesion, chemotaxis, chemokinesis, and plan...

https://www.mbl.edu/zebrafish/files/2013/03/Solnica-Krezel-and-Sepich.pdf

Gastrulation: Making and Shaping Germ Layers

On the role of serotonin and acetylcholine in sea urchin morphogenesis.

Microaquaria for time-lapse cinematographic studies of morphogenesis in swimming larvae and observations on sea urchin gastrulation.

Studies on enzymes in the developing sea urchin egg

Studies on mitochondria in the developing sea urchin egg

Publisher Summary This chapter discusses the enzymatic aspects of embryonic differentiation. The enzyme studies are supplemented by an investigation of the amino acid composition of the developing egg and the studies of its serologic and cytologic properties. The total changes in the amino acid composition of the developing egg were found to be rather insignificant. As a rule, no changes appeared before the hatching blastula stage or around the onset of visible differentiation in the advanced blastula. More pronounced changes were noted in the fractions of free amino acids, peptides, and certain peptidic growth-promoting compounds. Transient or permanent depletions in these fractions signal the onset of new and intense biochemical processes in the advanced blastula. Studies on antigenic and enzymatic development support the impression that the cleavage stages are a silent phase in many respects. New antigens thus could not be demonstrated in sea urchin development before the early gastrula stage. Between this stage and the pluteus stage, a new serologic component turned up. The activity of a series of enzymes was low and comparatively constant during the cleavage stages but increased in the advanced blastula or during gastrulation. This series of enzymes includes alkaline phosphatase, dehydrogenases, glutaminase I, cathepsin II, apyrase, and cholinesterase.

Tryggve Gustafson

Papers

On the role of serotonin and acetylcholine in sea urchin morphogenesis.

Microaquaria for time-lapse cinematographic studies of morphogenesis in swimming larvae and observations on sea urchin gastrulation.

Studies on enzymes in the developing sea urchin egg

Studies on mitochondria in the developing sea urchin egg

Enzymatic Aspects of Embryonic Differentiation