Dorsal blastopore lip organizer3/10/2024 Reduction of expression of β-catenin in the nucleus correlated with loss of vegetal cell fates. Treatments of lithium chloride sufficient to vegetalize the embryo resulted in increases in nuclearly localized b-catenin. Through a series of experiments, one study confirmed the role of β-catenin in the cell-autonomous specification of vegetal cell fates and the micromeres inducing ability. It was observed that β-catenin was present in the nuclei at the vegetal pole of the blastula. The animal cells are not determined because the micromeres can induce the animal cells to also take on mesodermal and endodermal fates. The micromeres induce the nearby tissue to become endoderm while the animal cells are specified to become ectoderm. The anterior/posterior axis lies along the animal/vegetal axis set up during cleavage. Specification in sea urchins uses both autonomous and conditional mechanisms to determine the anterior/posterior axis. Another type of specification is syncytial specification, characteristic of most insect classes. A cell specified conditionally will develop into a specific fate based upon other surrounding cells or morphogen gradients. A cell specified autonomously will develop into a specific fate based upon cytoplasmic determinants with no regard to the environment the cell is in. There are two main types of specification: autonomous and conditional. A cell that is specified can have its commitment reversed while the determined state is irreversible. Specification is the first stage in differentiation. In terms of developmental commitment, a cell can either be specified or it can be determined.
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