Liver foetal development

Tetrahydrocannabinol is metabolized in the liver to form active metabolites which are further metabolized to inactive polar compounds these are excreted in the urine. Some metabolites are excreted into the bile and then recycled via the enterohepatic circulation. Because of their high lipophilicity, most active metabolites are widely distributed in fat deposits and the brain, from which sources they are only slowly eliminated. The half-life of elimination for many of the active metabolites has been calculated to be approximately 30 hours. Accordingly, accumulation occurs with regular, chronic dosing. Traces of the cannabinoids can be detected in the blood and urine of users for many days after the last administration. There is some evidence of metabolic tolerance occurring after chronic use of the drug. THC and related cannabinoids readily penetrate the placental barrier and may possibly detrimentally affect foetal development. 

It is only the ability of modern chemistry to detect very small quantities of materials that made the following discovery possible. In some recent research it was reported that one subtle way in which cancer tumours cells differ from normal cells is how they metabolize carbohydrates present on their surfaces. Cancer cells have far more of the carbohydrate sialic acid, which can be detected with MRI (magnetic resonance imaging) analytical techniques. It was found that the sialic acid normally appears on the surface of the cells only in foetal development, but it appears abnormally in patients with gastric, colon, pancreatic, liver, lung, prostate and breast cancers, as well as in leukaemia. Research is continuing.1... 

All forms of mercury are acutely toxic to humans and animals, accumulating in the liver, kidney and brain, and some forms may cause abnormalities in foetal development (teratogenic). The main forms of mercury in the environment are the native nietal, inorganic salts of the (-1-1) and (-1-2) oxidation states and... 

AFP is a 70 kDa glycoprotein found in the circulatory system of the developing foetus. It is synthesized primarily by the yolk sac and (foetal) liver. AFP is present only in vanishing low quantities in the serum of adults (where it is replaced by serum albumin). Elevated adult serum levels of this marker are often associated with various cancers of the liver, as well as germ cell tumours. It is also sometimes expressed by gastric and pancreatic cancer cells. Although a useful tumour marker, increased serum AFP levels also often accompany cirrhosis and some other non-cancerous liver diseases. 

Stem cells are progenitor cells which are not yet specifically formed. They can multiply almost infinitely and form nearly all 210 tissue types in the human being. Depending on their derivation, they are defined as follows .) embryonal (= taken from the inner cell mass of the blastocysts), (2.) foetal (= isolated from 5-9 week-old abortive foetuses, and (5.) adult (= taken from the tissue of adults or children by means of biopsy or from the umbilical cord of newborns. Adult stem cells are limited in number and life span they do, however, have a broader development potential than so far assumed. They have also been found in the liver. The transformation of stem cells from the bone marrow into hepatocytes has been carried out successfully. Liver stem cells (7-15 gm) can develop both primary cell types of the liver, (7.) mature hepatocytes and (2.) biliary epithelial cells. These stem cells are deemed to be genuine liver stem cells, and not merely derived from the activation of immature oval cells in the liver. (54,59, 60, 81) (s. fig. 2.20)... 

There is clear evidence from many different sources that the metabolism of compounds may be involved in their teratogenic effects, as will be seen in the final chapter in the discussion of thalidomide and diphenylhydantoin teratogenicity. The embryo and foetus of some species clearly have metabolic activity towards foreign compounds which may be inducible by other foreign compounds. Thus, foetal liver from primates has a more well-developed metabolic system for xenobiotics than does that from rodents and rabbits for example. This may be due to the late development of the smooth endoplasmic... 

---