Question

Ectoderms, mesoderm and endoderm are the three germ layers. Which layer among the three gives rise to the connective tissue?
A) Ectoderm
B) Endoderm
C) Mesoderm
D) Endomesoderm

Answer 1

Hint: Germ layers are developed at the early stages of embryonic development. It is the primary cell layer which consists of the outer ectoderm, middle mesoderm and inner endoderm. The layer which produces connective tissue is developed after the development of the other two layers.

Complete answer:
The germ layers are formed during the gastrulation process as three layers ectoderm, endoderm and mesoderm. All the tissues and organs arise from these three germ layers.

Let us discuss the three layers-
The ectoderm is the outer layer so it forms the outer layer of the body. It forms some epithelial cells lining the skin, nails, hairs, glands of the skin, salivary glands, nerve tissues, peripheral nervous system etc.

The endoderm is the innermost layer that forms the internal linings of the body including the stomach, liver, pancreas etc. It forms some organs like the lungs, liver, pancreas, colon, stomach etc.

Mesoderm- is the middle layer that is formed after the formation of ectoderm and endoderm. This layer gives rise to the dermis, muscle system, heart, bones, bone marrows and blood which is known as fluid connective tissue. Mesoderm is the layer that is absent in lower organisms that exhibit radial symmetry and is present in the bilaterally symmetrical higher organisms. The mesoderm protects the organs by bathing them in the connective tissue.

Endomesoderm- It is the embryonic blastomere that is yet to be differentiated into endoderm and mesoderm. This layer can give rise to both the germ layers.

Hence the correct answer is option ‘C’.

Note: Connective tissues are the tissues that provide support, binds several organs, protects the organs and tissues within the body. It is made up of cells, fibres and ground substance. An example is a Blood. It is made up of plasma and cells(RBC, WBC, platelets).