Oviparity, Viviparity, Masupialization and Mammalian Evolution

It is a fascinating story how placenta came into existence from an unprotected egg to marsupian duck bill platipus to the nursing mother.

I won't go into evolution but write a few lines about the placenta for posterity.

The placenta is a big parasite.

It evades maternal immune rejection and we have not yet worked out its mysterious ways.

It is discarded with only a cursory look,  at the time of birth, since the baby is the center of attraction.

After 1970s only a few have done any in depth studies.

I am not going to land with list of questions but take a little pause and write few lines.

I have done some basic investigations which are published for perusal but never bothered to write a few line of its mastery in evasion of hostility in evolution.

Placental HLA or human leukocyte antigens are different from maternal antigens.

It is intimately associated with maternal blood and maternal antibodies and lymphocytes.

Its HLA antigens arise early in embryonic development and it projects a potent barrier while invading the maternal uterus.

It has two layers one foetal and one maternal.

Amnion and Chorion (from which the placenta develops) are foetal.

It has only two layers of cells, the cellar cytotrophoblast layer and the multicellular syncytiotrophoblast layer.
Only the multicellular counterpart is seen when the placenta becomes mature.

It does not become old but gradually  disintegrates after 40 weeks.

It resembles the symbiotic cell at the beginning of evolution, all mucoprotein but no nuclear material and a few fragments of nuclear material arranged as syncytial knots.

How does a large syncytium works in a all pervasive cellular world?

That is the only question of mine in this piece.

Basalis is the maternal mesoderm that gets vascularized gradually and extensively.

Basalis is maternal where spiral arteries empty its contents and filter all foetal blood to maternal venous sinuses.

It grows up to 40 weeks of gestation and wither off by 42 weeks.

It provides all the foetal hormones and control the maternal pituitary gland.

That's all about it.

HCG or Human Choriogonadotrophic Hormone is foetal and no counterparts in adults except its oestrogenic and progesterone actions.

My only contribution here is the large and mysterious Fibrinonection, mucopolysaccharide and protein molecule that are seen in the placenta especially up to 36 weeks of gestation which provide a ground base of nutrition and virtual mop up molecule  or barrier for maternal antibodies present and in evolution, over the course of pregnancy..

This is almost same to the Fibrinonectin that exudes at the site of injury before granulation tissue of healing invades it.

Almost the same Fibrinonectin that provides a scaffolding for the cancer cells to form an angiogenic front.

So in my view, Fibrinonectin which I call the molecular glue does all the work by itself without a nucleus.

So it may be the grand old evolutionary molecule equal in potential to heat shock protein that started the life on this planet.

Nobody has done any worthwhile work on Heat Shock Protein (HSP) that are present in prokaryocytes and eukaryocytes.