Comparison of Lymphoid Organs and Lymphoid Cells

 Lymphoid Organs and Lymphoid Cells Comparison

Immune System | Biotechnology

The focus of today’s discussion would be the Comparison between lymphoid cells and the lymphoid organs.

The two major keywords of this topic are lymphoid cells and lymphoid organs are well explained before in the previous discussions and will guide us in better understanding of the current topic.

Please follow my posts, Cells of Immune System and Organsof Immune System, if not gone through before, this post will help you in understanding the terms and facts and includes both ‘Cells of Immune system’ as well as ‘Organs of Immune System’ in Biotechnology, which will be coming further in this topic.

So, let’s start discussion on Lymphoid Cells and Lymphoid Organs, later in this post we will try to correctly compare both of them.

Immune Cells or Lymphoid Cells and Immune organs or Lymphoid Organs :

The main cells or lymphocytes which are involved in an immune response are known as immune cells or lymphoid cells.

The organs which are involved in the production of immune cells and their respective reactions are called immune organs or lymphoid organs.

Mainly lymphoid cells and lymphoid organs are present only in vertebrates.

Only vertebrates possess adaptive immunity*, which is governed by antibodies and T cells.

All vertebrates have gut associated lymphoid tissue (GALT) and most of them have a simple type of spleen and thymus.

Most Importantly, bone marrow and lymph nodes are not present in all the vertebrates.

At cellular level, both lymphoid cells and lymphoid organs also exhibit some differences.

Lymphocytes having antigen specific receptors on their surface are required to mount an adaptive immune response.

Jawed vertebrates are the only example to have B and T lymphocytes and support adaptive immune response.

Evolutionary Line Of Development of Lymphoid Organs and Lymphoid Cells:

The process of evolutionary development of  lymphoid organs and lymphoid cells evolved in the following way.

·        In Invertebrates:

Hematopoietic stem cell give rise to phagocytes, which shows germ line encoded pattern recognition receptors.

·        In Jawless Vertebrates :

The hematopoietic system also produces lymphocyte like cells which express somatically diversified antigen (Ag) receptors.

·        In hypothetical intermediate I :

The hematopoietic stem cells also start producing a second lineage of lymphocyte like cells, which shows structural invariant proto TCR (T cell receptor).

·        In hypothetical intermediate II :

Occurrence of transformation of structurally variant proto TCR into somatically diversible VDJ type TCR through transposon mediated insertion.

·        In Jawed Vertebrates :

The hematopoietic stem cell finally gives rise to B lymphocytes or cells which express somatically diversified antigen receptors.

Step by Step tabular Data on Comparative evolution of Lymphoid Organs and Lymphoid Cells:

Steps	Lymphoid Cells	Lymphoid Organs
I	Myeloid cells including phagocytes	Myeloid tissue
II	Myeloid cells with B lymphocyte like cells	Lympho- myeloid tissue (spleen)
III	Addition of proto T cells	Lympho- myeloid tissue (spleen and thymus )
IV	T cell expressing modern TCR (T cell receptor)	Lympho- myeloid tissue ( bone marrow or equivalent and thymus)
V	T cell expressing modern TCR (T cell receptor) and B cells express modern BCR (B cell receptor)	Lympho- myeloid tissue ( bone marrow and thymus)

The above information gives you a better understanding on the evolution of lymphoid organs and lymphoid cells and a better and easy comparison between the lymphoid organs and lymphoid cells.

I believe after reading this post, you can explain about ‘Evolution of Lymphoid Organs and Lymphoid Cells’ and ‘Comparison between Lymphoid Organs and Lymphoid Cells’ by yourself now.

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Happy Lymphoid Organs and Lymphoid Cells Learning!!!