The cells of inner cell mass of a blastocyst stage mammalian embryo are
pluripotent
The question asks about the potency of the cells found in the inner cell mass of a blastocyst stage mammalian embryo. Understanding the different types of cell potency is key to answering this.
Blastocyst Structure and Inner Cell Mass
A blastocyst is an early stage of mammalian embryo development, typically formed about 5-7 days after fertilization. It consists of two main parts:
- Trophoblast: The outer layer of cells. These cells will primarily form the placenta and other extraembryonic tissues.
- Inner Cell Mass (ICM): A cluster of cells located inside the trophoblast. These cells will develop into the embryo proper, forming all the tissues and organs of the baby.
Understanding Cell Potency
Cell potency refers to a cell's ability to differentiate into other cell types. Different levels of potency exist:
- Totipotent: These cells can differentiate into any cell type, including the placenta. The zygote and the cells in the early morula stage are totipotent. They can form a complete organism.
- Pluripotent: These cells can differentiate into any of the three primary germ layers (ectoderm, mesoderm, and endoderm), which collectively give rise to all the cell types of the body. However, they cannot form the placenta or other extraembryonic tissues.
- Multipotent: These cells are more restricted. They can differentiate into a limited range of cell types within a specific lineage or tissue type. For example, hematopoietic stem cells in bone marrow can differentiate into various types of blood cells.
- Unipotent: These cells can only differentiate into a single cell type.
Inner Cell Mass Cell Potency
The cells of the inner cell mass are crucial because they will give rise to the entire embryo. These cells have the remarkable ability to differentiate into cells of the ectoderm, mesoderm, and endoderm, which are the precursors to all the body's tissues and organs. However, the inner cell mass cells alone cannot form the placenta; that is the role of the trophoblast.
Based on the definitions of cell potency, the cells of the inner cell mass fit the description of being able to differentiate into all cell types of the body but not the extraembryonic tissues like the placenta.
Conclusion on Inner Cell Mass Cells
Therefore, the cells of the inner cell mass of a blastocyst stage mammalian embryo are considered pluripotent.
Important Questions from Basic concepts of development
Following statements are made regarding animal development:
A. The cell is first specified towards a given fate, suggesting that it would develop into this cell type, even in a neutral environment.
B. Holoblastic rotational cleavage is observed in tunicates.
C. Infolding of sheet of cells is called ingression.
D. Conditional specification can be observed in sea urchin embryos.
Which one of the following options represents the combination of all correct statements?
C. elegans embryo uses both autonomous and conditional modes of specification. The following statements are about specification of cell lineages:
A. The signals from the P1 blastomere instructs the EMS cell for its further development.
B. In the absence of the instructive signal, the EMS cell will divide into two MS cells.
C. In the absence of the POP‐1 signal, the prospective MS cell can take up the E fate.
D. The MOM‐2 protein from the blastomere neighbouring the EMS cell instructs the dividing EMS blastomere to take up MS fate.
Which one of the following options represent both correct statements?
When 8-cell embryo of tunicates is separated into 4 blastomere pairs and allowed to grow independently in culture medium, then each blastomere pair can form most of the cell types; however, cells for nervous system are not developed. The following statements are formed from the above observations:
A. Nervous system development demonstrated autonomous specification.
B. The other tissue types are formed due to conditional specification.
C. All the tissue types, except nervous tissues that developed, demonstrated autonomous specification.
D. Nervous system development demon-strated conditional specification.
The correct combination of statements that explains the above result is:
Which one of the following statements about stem cells is correct?
Following statements are being made regarding specification/determination during animal development:
A. During the course of commitment, the cell may not appear different from its nearest or most distant neighbours in the embryo and show no visible signs of differentiation; but its developmental fate is restricted.
B. At the stage of specification, cell commitment is not labile.
C. A cell or tissue is determined when it is capable of differentiating autonomously even when placed into another region of the embryo, or a cluster of differently specified cells in a petri- dish.
D. Cytoskeletal arrangements maintain positioning of nuclei in the syncytium, which enables specification of these nuclei by opposing morphogen gradients namely Bicoid and Caudal in Drosophila.
E. Capacity for “mosaic" development allows cells to acquire different functions as a result of interactions with neighbouring cells.
Which of the above statements are correct?
