Question

Ontogenetically liver and pancreas are
(a) Ectodermal
(b) Mesodermal
(c) Endodermal
(d) None

Answer 1

Hint: There are three layers of germ cells in the human embryo- inner endoderm, middle mesoderm, and outer ectoderm. Some animals are there who produce only two germ layers whereas poriferans don’t have any germ layers.

Complete answer:
Ontogenetically liver and pancreas are endodermal, along with other organs such as thyroid, parathyroid, gastric and intestinal glands, branch, trachea, and lungs. Endoderm forms the epithelium that is the lining of the primitive gut. Along with the other two layers, ectoderm and Mesoderm, the endoderm was discovered by Christian Pander in 1817.
So, the correct answer is ‘Endodermal’.

Additional Information: All organisms except Porifera phylum form two or three germ layers through gastrulation. A mass of cells transforms into a two-layered embryo made of endoderm, the inner layer, and ectoderm, the outer one. In complex organisms, another layer is found in between these two known as mesoderm. Cells migrating inward from the gastrula develops into the endoderm.
It consists of flattened cells at first and then becomes columnar and forms the epithelial lining of various systems. In the gastrointestinal region, almost the whole alimentary canal except the mouth, pharynx, and rectum, all the digestive glands are made of endoderm. That means the liver and pancreas also originated from the endoderm.
In other regions such as the respiratory tract trachea, bronchi and alveoli are made from endoderm. The urinary bladder and part of the urethra are also derived from endoderm.

Note: The endoderm differentiates into distinguishable organs into 5 weeks of pregnancy. The cells of the liver and pancreas are derived from a common precursor. In the case of plants, the innermost part of the cortex in young shoots and roots corresponds to the endoderm, which lignifies with age.