Invagination of the sea urchin blastulaA. is preceded by changes in the shape of individual blastomeres.B. involves the filopodia of secondary mesenchyme cells.C. is due to the uneven distribution of various transcriptional regulatory proteins in the egg cytoplasm.D. forms the archenteron.E. All of the above
Invagination of the sea urchin blastula
A. is preceded by changes in the shape of individual blastomeres.
B. involves the filopodia of secondary mesenchyme cells.
C. is due to the uneven distribution of various transcriptional regulatory proteins in the egg cytoplasm.
D. forms the archenteron.
E. All of the above
Invagination is a process occurring during gastrulation. It includes movement of cells at the vegetal pole towards interior side of the blastula. Sea urchins are deuterostomes; therefore blastopore later on develops into anus.
Explanation of all the options:
A. is preceded by changes in the shape of individual blastomeres: Blastomeres are the cells present in the blastula stage of developing embryo. Blastomeres change shape before the inward movement of these cells. Therefore, it is a correct option.
B. involves the filopodia of secondary mesenchyme cells: Secondary mesenchyme cells forms a separate subset of blastocoelar cells. These cells forms various filopodia that forms network of processes of cytoplasm within the arms of larva, along skeletal rods, and around gut. Therefore, it is a correct option.
C. is due to uneven distribution of various transcriptional regulatory proteins in the egg cytoplasm: Transcription factors are the proteins that stimulate the transcription of different genes. These are distributed unevenly in the cytoplasm of the egg. Therefore, it is a correct option.
D. Forms the archenteron: In invagination, blastomeres changes shape and moves inside. This led to the formation of archenteron. Therefore, it is a correct option.
E. All of the above: Since all the above options are correct for the given question therefore, it is the correct option.
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