Fetal pig anatomy and physiology, Detailed explanations would be very aprecciate

Question

Fetal pig anatomy and physiology, Detailed explanations would be very aprecciated!

1. The presence of the allantoic duct in the umbilicus provides a clue regarding how the functional roles of extraembryonic membranes in placental mammals have been modified evolutionarily from their roles in chick development. Explain!

2. What function does the umbilical cord play in a fetal mammal? To what does it connect? What are the functional roles of the umbilical artery and vein (and which carries more oxygen)?

3. From which embryonic germ layer does the coelomic lining (peritoneum) arise? By what process do the coelomic cavities develop?

4. How does a fetal pig obtain oxygen? What triggers the changeover to

Explanation / Answer

1.

The embryos of all vertebrates need an aqueous environment for the development. Fishes and amphibians lay their eggs in the surrounding sea or pond, so they do not need any special water filled sac in their embryo. But, this requirement limited the process of reproduction in dry environment. So, this difficulty was overcome during evolution by some structural adaptations such as extraembryonic membranes present in the chick. The extraembryonic membranes in birds are derived from the parts of germ layer located outside the embryo. The four extraembryonic membranes are,

1. Chorion: This layer completely surrounds the embryo and exchange of gases occurs between the embryo and surrounding air.

2. Amnion: This encloses the embryo in a fluid-filled cavity which offers protection against dehydration and mechanical shock.

3. Yolk sac: It surrounds the yolk and the blood vessels of this membrane transport nutrients from the yolk into the embryo.

4. Allantois: This membrane acts as a disposal sac for metabolic wastes produced by the embryo and also involved in gaseous exchange.

Q2). Umbilical cord is connected to placenta. In any mammalian foetus, umbilical cord contains blood vessels, through the blood vessels it trasport nutrition from the placenta to the foetus. Umbilical vein carries oxygenated blood from placenta to foetus. The two umbilical arteries carry deoxygenated blood from fetus to placenta.

Q3). The

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