Alright, guys…I need to know the answer to this question by 6 PM tonight. I’ve got a final in Anatomy and Physiology II, and this is going to be an extra credit question. I’ve searched and found nothing…so if anyone can help, I’d really appreciate it.
so…
Why are the lobes of the thymus gland asymmetrical?
epraz,
found this quote:
"Right lobe is larger than left lobe in 48% of people and left lobe larger than right lobe in 12% of people. "
here:
http://www.medpharm.co.za/tmj/nov_dec2000/thyroid.html
So, that’s only 60% of the population that has one lobe larger than the other. I’ll look around a little more and post if I find something.
Shoot, I did all this research looking for why the thymus was symmetrical. For what it’s worth, here it is:
Functional asymmetry of thymus and the immune response in mice.
Abramov VV, Gontova IA, Kozlov VA.
Research Institute of Clinical Immunology, Siberian Branch of Russian Academy of Medical Science, Novosibirsk, Russia.
We have studied the capability of the mouse thymus for asymmetrical formation. Concanavalin A (Con A)-stimulated proliferation of thymocytes from the right and left lobes of the thymus appeared to be significantly different. The direction of the differences depends on the dominance of the brain hemispheres with regard to motor asymmetry. In mice with right-dominant hemispheres, thymocytes from the left lobe of the thymus demonstrate a higher level of Con A-stimulated proliferation than those from the right lobe. In mice with left-dominant hemispheres, we found the opposite dependence. The in vivo experiments showed that the properties of cells from the contralateral lobes of the thymus proved to be a deciding factor that defines the differences at the level of the immune response in recipient mice with left-dominant hemispheres. This effect was less pronounced in mice with right-dominant hemispheres. Further analysis showed that left and right-dominant hemisphere mice differ according to the immune response only if mice from both groups received cells from the left but not from the right lobe of the thymus. That is, in the formation of the immune response to sheep red blood cells, the functional asymmetry of both the brain and thymus is of great importance. The experiments show that brain hemispheres and cells from different lobes of the thymus are able to interact in the regulatory effect on the immune response. The injection of cells from the thymus lobe ipsilateral to the dominant hemisphere, results in a significant excess of the immune response in left-dominant hemisphere mice in comparison with the response of right-dominant hemisphere mice. It can be concluded that this work demonstrates, for the first time, the asymmetrical function of a bilateral immune organ – the thymus. The asymmetry is shown not only at the level of Con A-induced proliferative activity but also at the level of the influence on the humoral T-dependent immune response in mice. Besides, we have found the interaction of brain hemispheres and thymus lobes in the regulation of the immune response. Copyright 2002 S. Karger AG, Basel
Bull Exp Biol Med 2001 Jan;131(1):64-6
Asymmetry in cerebral hemispheres and thymus lobes during realization of humoral immune response in mice.
Gontova IA, Abramov VV, Kozolov VA.
Institute of Clinical Immunology, Siberian Division of the Russian Academy of Medical Sciences, Novosibirsk.
We studied the role of functional asymmetry in mouse brain and thymus in the realization of humoral immune response. We concluded that not only nervous system asymmetry, but also immune system asymmetry and the relationship between cerebral hemispheres and cells of the right and left thymus lobes play an important role in the regulation of immune response.
PMID: 11329086 [PubMed - indexed for MEDLINE]
http://www.thelancet.com/search/search.isa:
Articles above from link in footnote of article found at The Lancet site (hyperlink above):
Immune constitution of complete DiGeorge anomaly by transplantation of unmobilised blood mononuclear cells
Daniel C Bowers, Howard M Lederman, Scott H Sicherer, Jerry A Winkelstein, Allen R Chen
At a superficial reading, the articles seemed to indicate an asymmetrical thymus was not a good thing, which I figured was why the thymus was symmetrical. But it’s not, is it? Anway, maybe the articles and links will put you on the right track.