How Do Cytoplasmic Determinants Affect Cell Differentiation

Cytoplasmic determinants are a type of substances found in the female gametes; they are responsible for the regulation of gene expression in the early development of the embryo. They lead to the differential specialization of blastomere during cleavage. Blastomere is the resultant cell from the mitotic divisions in the zygote. The specialization of the cells in the blastomere is a type of asymmetric cell division. Asymmetric cell division gives rise to daughter cells with distinct development fates. Along with the cytoplasmic determinants, signaling cascades are also involved in the cell differentiation during the embryonic development stage.

Key Areas Covered

1. What are Cytoplasmic Determinants
– Definition, Types, Function
2. How Do Cytoplasmic Determinants Affect Cell Differentiation
– Function of Cytoplasmic Determinants in Cell Division

Key Terms: Blastomere, Cell Differentiation, Cytoplasmic Determinants, Three Germ Layers, Uneven Distribution

What are Cytoplasmic Determinants

Cytoplasmic determinants are the substances present in the egg or blastomere, determining the fate of the cells during cleavage. They also play an important role in oocyte maturation. They can be proteins, mRNA, organelles or other substances that are unevenly-distributed inside the cytoplasm. Cytoplasmic determinants are found in the female gamete. Due to the uneven distribution of cytoplasmic determinants within the cell, an uneven cell division can be observed. Therefore, the daughter cells formed by the cell division may have different cytoplasmic environments.

How Do Cytoplasmic Determinants Affect Cell Differentiation

The zygote is the conceptus of fertilization, and the cell division of the zygote is known as cleavage. It creates a cell mass known as blastomere that cleaves further to form the three germ layers endoderm, ectoderm, and mesoderm in the process of embryonic cell specialization. The cells in the blastomere are specialized into cells in the three germ layers by the action of both cytoplasmic determinants and cell signaling. The differentiation of cells during embryonic development is shown in figure 1.

Figure 1: Cell Differentiation during Embryonic Development

The main role of cytoplasmic determinants is to regulate the gene expression. Since different daughter cells inherit differential amount of cytoplasmic determinants, the type of cells inherited in each type of daughter cells also differ. Therefore, the type of genes that are expressed in each type of daughter cells are different. The differential regulation of gene expression is achieved in both transcriptional and translational levels.

The differential cell division that occurs in oocyte maturation is also due to the uneven distribution of cytoplasmic determinants within the cytoplasm of different cell stages in oocyte development.

Conclusion

Cytoplasmic determinants are a type of substances found in the cytoplasm. They are unevenly-distributed within the cytoplasm. The main role of cytoplasmic determinants is the regulation of gene expression. Due to the uneven distribution of cytoplasmic determinants within the cytoplasm, the daughter cells inherit different amounts of them during cell division. Therefore, the gene expression in daughter cells may also differ from each other.