Teratogens, Biology

TERATOGENS -

  • These are chemicals or drugs causing malformed foetus.
  • The production of monsters or malformed foetus is called tertogeny or teratogenesis.
  • The ability of a drug to cause foetal abnormalities when used by pragnant women is termed teratogenicity.
  • Study of malformed babies is known as teratology.
  • Teratogens may affect embryogenesis by disturbing one or more development processes.
  • They may cause over developed & under development of tissue or organs.
  • There are three main categories of teratogens -

1.       DRUGS AND CHEMICALS -

(i)       Alcohol may cause foetal alcohol syndrome (FAS). It includes deficient prenatal growth, facial abnormalities, mental retardation.

(ii)      Thalidomide may cause phocomelia i.e. hands & feet are attached close to body, resembling the flippers of a seal, ear anomalies, cardiac malformation, closed oesophagus, failure of kidney development.

(iii)     Diazepam (Valium) use increases the risk of oral cleft.

(iv)     Halucinogens - THC causes birth defects, LSD produces chromosomal & foetal abnormalities.

(v)      Quinine (Malaria), bubulphan (Leukemia), chlorambucil (Hodgkin's diseases) aminopterin (abortion) seriously harm the foetus.

(vi)      Tetracycline increases susceptibility to caries, streptomycin increase susceptibility to hearing loss.

(vii)     Epileptic woman should discontain anticonvalsant drugs (Dilantin) during pregnancy as it causes foetal hydantain syndrome (FHS) characterised by poor prenatal growth short limbs, mental retardation, facial anoma- lies, cardiovescular abnormalities.

(viii)     Many pragnent woman take progestin or estrogen to avoid abortion. Use of these hormones causes masculinization of the ext. genitilia in female foetuses.

If hormone cortisone and vit. A taken in excess during early pregnancy, cause foetal defects such as hydrocephalus (very large head).

(ix)     Tobacco smoking by pregnant women leads to poor foetal growth & increases risk of abortion, intrauterine foetal death, neonatal death and premature birth.

2.       INFECTIOUS AGENTS -

Viral, bacteria and parasitic infections may cause serious effect on foetus.

3.       RADIATION -

Exposure to ionizing radiation of 2 to 6 weeks old foetus is teratogenic. It may cause pregnancy loss, growth retardation, eye malformation and CNS defects.

May cause mutation and leukemia.

Posted Date: 10/4/2012 9:08:27 AM | Location : United States







Related Discussions:- Teratogens, Assignment Help, Ask Question on Teratogens, Get Answer, Expert's Help, Teratogens Discussions

Write discussion on Teratogens
Your posts are moderated
Related Questions

Q. What is the pollination? What are the major forms of pollination? The procedure in which pollen grains (the male gametophytes of phanerogamic plants) reach the female gameto

How different are gymnosperms from pteridophytes and bryophytes? Gymnosperms are not cryptogamic as pteridophytes and bryophytes are. They are phanerogamic and so they form see

How many distinct hexapeptides can be made from 20 amino acids?

Are nematodes exclusively parasites? There are parasitic roundworms, containing parasites of plants, but there are also free-living nematodes.

Explain about Hypothalamus Another important part of brain is hypothalamus. It is very small in sie. It controls many important functions which are as follows:  Blood pre

The important functional characteristics of soy protein The most important functional characteristics of soy protein concentrates are water-binding (water adsorption) capacity,

Q. Show types of hiatus hernia? Depending on the extent of herniation and placement of stomach, it could be of two types: 1, Para Oesophageal Hernia (oesophagus is in normal

Where do the two neuronal pathways diverge For both the neuronal pathways i.e. light reflex and near reflex the efferent fibres go to are 3rd cranial nerve and then to sphinct

You are interested in plant life history evolution, you come across a population of the California poppy that i spolymorphic (mixed) for both iteroparous ans semeparous individuals