Question

Embryonic induction is best illustrated by the following:
A. Developing of the chorion in a developing chick embryo
B. Replacement of cartilage with bone in a developing embryo
C. Development of ectoderm into skin
D. Development of neural tube after contact with the dorsal mesoderm

Answer 1

Hint: All the multicellular organisms develop into an adult organism through several stages. An embryo is the earliest stage of development in a multicellular organism forming after fertilization of the gametes.

Complete answer:
In multicellular organisms, the action of one group of cells or tissue influences a developmental pathway in the further stages of development. In other words, a group of cells or tissue helps in the development of another group of cells having a different function. This process is known as embryonic induction and the cells or tissue responsible for the process is known as an Inducer. An illustration of embryonic induction can be seen during the development of the chorion in a developing chick embryo.
Considering the other given options:
B. This process of replacement of cartilage with bone in a developing embryo is known as endochondral ossification. It cannot be considered as embryonic induction since it involves the process of differentiation from chondrocytes to osteocytes.
C. In the process of development of ectoderm into skin, the ectoderm itself gets differentiated to form the epidermal layer and hence cannot be regarded as embryonic induction.
D. The development of the neural tube is caused due to the elongation of the ectoderm.

So, the correct answer is “Option A”.

Note:
In a chick embryo, the chorion is formed from the mesoderm that lies extra embryonic as well as
From the trophoblast. It functions as a double layered outer membrane. The fetal placenta gets
Developed from the chorion.