Pregnancy And Embryonic Development

The correct answer is Option B) ectoderm and mesoderm

The developing fetus resides in the amniotic cavity, surrounded by the amnion membrane. The amnion membrane is derived from the extra somatic ectoderm on the inner side and mesoderm on the outer side. The extraembryonic or fetal membranes consist of the amnion, chorion, allantois, and yolk sac.

• The amnion is formed from the mesoderm on the outer side and ectoderm on the inner side.
• The chorion is formed from the trophoectoderm and mesoderm.
• The allantois and yolk sac membranes have mesoderm on the outer side and endoderm on the inner side.

Therefore, Option B is the correct answer.

Discover More From the Concept: Embryology

In angiosperms, the fertilized embryo sac contains structures that are haploid, diploid, and triploid. To determine these structures sequentially, we need to understand their formation:

1. Haploid Structure: Synergids are part of the egg apparatus and are haploid. They play a crucial role in directing the growth of the pollen tube to the egg cell.
2. Diploid Structure: The fertilization of an egg cell by a sperm cell results in a zygote, which is diploid (2n). This marks the beginning of the embryonic development.
3. Triploid Structure: The secondary fertilization in angiosperms involves the fusion of another sperm cell with the two polar nuclei to form the primary endosperm nucleus, which is triploid (3n). The endosperm provides nutrition to the developing embryo.

Thus, the sequence of haploid, diploid, and triploid structures in a fertilized embryo sac is Synergids, Zygote, and Primary endosperm nucleus.