Embryonic Development

Pluripotency refers to a stem cell that has the potential to differentiate into any of the three germ layers: endoderm, mesoderm or ectoderm.

This is the correct option. Platyhelminthes and chordates are the animals in which the developing embryo has a third germinal layer, called the mesoderm, in between the ectoderm and endoderm.

Parthenogenesis is defined as the process in which the new individual is produced directly from the egg without undergoing fertilization. Honey bee, rotifers and some species of fishes and lizards in vertebrates exhibit the phenomenon of parthenogenesis.

Embryonic stem cells (ESCs) are derived from the inner cell mass of a fertilized embryo at the blastocyst stage (approximately 5-7 days post-fertilization in humans). Option A is correct. Unfertilized embryo (B) is a contradiction in terms - an embryo by definition results from fertilization. ESCs cannot be derived from sperm (C) alone or adult tissues like kidney (D) - those would be adult stem cells if any. The key feature of ESCs is their pluripotency, derived from the earliest stages of embryonic development after fertilization has occurred.

The liver develops from the endodermal germ layer during embryogenesis, arising as an outpouching of the foregut. This endodermal origin is consistent with the digestive tract and its accessory organs. Ectoderm forms skin and nervous tissue, while mesoderm forms muscle, bone, and connective tissue.

The epidermis is the outermost layer of skin and develops from the ectoderm, one of the three primary germ layers in embryonic development. The ectoderm gives rise to superficial structures like skin epidermis, hair, nails, and the nervous system. Endoderm forms internal organs like the gut lining, while mesoderm forms muscles, bones, and connective tissue.

Uterus is the part where development of the baby takes place.

The embryo of hens develops inside the egg, which remain outside the female body.

Zygote is formed when a female egg is fertilised. It is the first stage of a new living individual. It is also considered as the beginning of a new individual.

Uterus is the organ where the zygote matures and grows till it is ready to be born. 

Fertilization is caused by fusion of gametes, which leads to formation of zygote. 

Placenta is linked with embryo by the umbilical cord. 

Within the uterus, the developing baby is surrounded by protective covering called amniotic sac. 

In oviparous reproduction (egg-laying), the embryo develops inside an egg outside the mother's body, nourished by yolk - not directly from the mother. In viviparous reproduction (live birth), the embryo receives nourishment directly from the mother via placenta. In ovoviviparous reproduction, eggs hatch inside the mother's body, and embryos get nourishment from yolk, not directly from mother.

Graffian follicles start out as immature structures called primordial follicles. These are present in females from birth and each contains a single egg cell or oocyte surrounded by a layer of follicular cells. At the beginning of every menstrual cycle, a number of primordial follicles grow larger and each one creates a fluid filled space around its ovum.