Modular Morphogenesis: Determinate Rhythmic Budding In Hydra

Abstract

The last half century of research on hydra’s morphology and morphogenesis has opened up a cornucopia of possibilities for future investigations. A preeminent question is, do the dynamics of hydra’s development and maintenance apply to other metazoan’s growth, physiology and pathology? Under favorable laboratory conditions, hydras achieve an optimal configuration and maintain a steady-state. In this state, continuous cell division in the body column is matched by the rhythmic removal of excess parental cells as buds in the budding region. Since, hydra’s buds form with the same number of tentacles present on animals in their optimal configuration, hydra’s form and its stability would seem built into buds. Depending on feeding schedule and temperature, parental cells are produced at different rates and move toward the budding region accordingly. These parental cells seem to accumulate in modules that upon filling up (with approximately 15,000 parental cells) sprout as incipient buds. Modules would form where gastric region cells moving down the body column collide with peduncle cells moving up. The circular muscle fibers of gastrodermal cells would seem to be reconfigured at this junction, and their contraction around modules project incipient bud sprouts outward, breaking with parental polarity and lineal parental constraints. The sprout adds new substratum (mesoglea); epithelial cells form the bud’s head, body column, and foot; individual interstitial cells become the stem-cells of nerve, gland, cnidoblast and sex cells. The concept that symbiogenic lies at the starting point of Cnidaria as well as the evolution of other metazoans suggests that what is true for hydra is true elsewhere. In addition to looking for remnants of cnidarian genomes in bilaterians, researchers might look at the morphogenesis and maintenance of epithelial appendages and carStanley Shostak* Department of Biological Sciences, University of Pittsburgh, USA Modular Morphogenesis: Determinate Rhythmic Budding in Hydra cinoma’s metastatic units for evidence reminiscent of hydra’s habit of discarding excess parental cells with pulsatory regularity. Researchers might also look at the accumulation and rejection of individual cells in vascular and connective tissue, lymphomas and sarcomas, reminiscent of hydra’s rejection of interstitial cells in buds. Citation: Shostak S (2019) Modular Morphogenesis: Determinate Rhythmic Budding in Hydra. J Cell Biol Cell Metab 6: 017.