This document is a student assignment on MALT, GALT and BALT submitted by Hina Zamir. It discusses the three topics in three paragraphs. MALT is mucosa-associated lymphoid tissue found throughout the body. GALT refers to gut-associated lymphoid tissue, including the tonsils, adenoid, appendix and Peyer's patches, which protect the gastrointestinal tract. BALT is bronchus-associated lymphoid tissue located in the conducting airways.

1. ASSIGMENT ON
“MALT ,GALT AND BALT “
SUBMITTED TO: SIR JAWAD
SUBMITTED BY:
HINA ZAMIR (ROLL NO 04)
6th_
SEMESTER
DATE: 22ND -FEB-2016
CENTRE OF BIOTECHNOLOGY AND
MICROBIOLOGY
UNIVERSITY OF PESHAWAR

2. TOPIC: GALT, MALT and BALT
1. MALT (mucosa-associatedlymphoid tissue):
The mucosa-associated lymphoid/ lymphatic tissue (MALT) is a diffuse system of small
concentrations of uncapsulated lymphoid tissue found throughout the lamina propria. It is found
in association with mucosal tissues of the body, such as the gastrointestinal tract, thyroid, breast,
lung, salivary glands, eye, and skin [1]. It may consist of a collection of lymphoid cells, or it
may include small solitary lymph nodes [2]
Histology:
MALT is populated by lymphocytes such as T cells and B cells, as well as plasma :cells and
macrophages, each of which is well situated to encounter antigens passing through the mucosal
epithelium. In the case of intestinal MALT,M cells are also present [1] having a role of
absorption, transport, processing, and presentation of antigens to subepithelial lymphoid cells[2].
MALT can appear as aggregations of immune cells roughly similar in architecture to a section of
a lymph node and may contain lymphoid follicles with germinal centers. Unlike lymph nodes,
MALT aggregations are not penetrated by lymphatic vessels and are exposed to antigens directly
from the mucosa they surround.

3. Role:MALT provides the immune system easy histological access to the organisms. Thus, it
allows the immune system to sample microbial antigens for development of adaptive immune
responses and provides a site for Plasma Cells to synthesize antibodies .
Anatomy : MALT is found in several prominent locations and the lymphoid collections at
each anatomical location are given some unique identifiers as discussed below.
 Bronchial Associated Lymphoid Tissue (BALT): Found in Conducting Airways,
specifically in the Respiratory Lamina Propria
 Gastric Associated Lymphoid Tissue (GALT): Found in the Stomach, specifically the
Gastric Lamina Propria
 Peyer's Patches: Found in the Small Intestine, specifically the Small Intestine Lamina
Propria
 Appendix: Contains abundant MALT in its lamina propria
 Tonsils: Tonsils are essentially MALT found mucosa of the pharynx [3]
2. GALT( Gut associatedlymphoid tissues):
The gastrointestinal tract's immune system is often referred to as gut-associated lymphoid
tissue (or GALT) and works to protect the body from invasion. The GALT is an example
of mucosa-associated lymphoid tissue.It includes tonsils, appendix, adenoids and peyer’s patches

4. 2.1 Tonsils:
The tonsils are a pair of soft tissue masses located at the rear of the throat (pharynx). Each tonsil
is composed of tissue similar to lymph nodes, covered by pink mucosa (like on the adjacent
mouth lining) [4] . Lymphocytes and macrophages in the tonsils provide protection against
harmful substances and pathogens that may enter the body through the nose or mouth.[5]
 Crypts: Running through the mucosa of each tonsil are pits, called crypts.
There are three groups of tonsils: Palatine tonsils ( near opening of oral cavity ) , lingual tonsils (
located on posterior surface of tongue ) and adenoids [5]

5. 2.2 Adenoid:
The adenoid, also known as a pharyngeal tonsil or nasopharyngeal tonsil, is the superior-most of
the tonsils. It is a mass of lymphatic tissue situated posterior to the nasal cavity.[6]
Waldeyerring: Both tonsils and adenoid are part of the Waldeyer ring, which is a ring of
lymphoid tissue found in the pharynx. The lymphoid tissue in this ring provides defense against
pathogens. The Waldeyer ring is involved in the production of immunoglobulins and the
development of both B cells and T cells. [7]
2.3 Appendix:
The appendix also called vermiform (worm shaped ) is a small tubular extension of the right side
of the colon.
Lymphoid tissue begins to accumulate in the appendix shortly after birth and reaches a peak
between the second and third decades of life, decreasing rapidly thereafter and practically
disappearing after the age of 60
Role: Appendix has a role in the maturation of B lymphocytes (one variety of white blood cell)
and in the production of the class of antibodies known as immunoglobulin A (IgA) antibodies. It
is also involved in the production of molecules that help to direct the movement of lymphocytes
to various other locations in the bod

6. The function of the appendix appears to be to expose white blood cells to the wide variety of
antigens, or foreign substances, present in the gastrointestinal tract. Thus, the appendix probably
helps to suppress potentially destructive humoral (blood- and lymph-borne) antibody responses
while promoting local immunity. The appendix--like the tiny structures called Peyer's patches in
other areas of the gastrointestinal tract--takes up antigens from the contents of the intestines and
reacts to these contents. This local immune system plays a vital role in the physiological immune
response and in the control of food, drug, microbial or viral antigens [8].
3. BALT (Bronchus-associatedlymphoid tissue):
BALT is part of the integrated mucosal-associated lymphoid tissue system. It is not present in all
species and age groups and can be classified as a tertiary lymphoid organ
Structure:
It is an accumulation of lymphoid cells with a typical localization of B lymphocytes
preferentially in a follicle and T lymphocytes, more peripherally around high endothelial venules
in the wall of bronchi.
Dome area: Another structural component is a cap-like accumulation of lymphoid cells partly
bulging into the lumen of the bronchus, called the dome area. The epithelium covering the dome
lacks goblet cells, is infiltrated by lymphocytes, and contains cells specialized for antigen
uptake-M cells [9]

7. 4. References:
1. Mucosa-associated lymphoid tissue. (2016, January 5). In Wikipedia, The Free
Encyclopedia. Retrieved 17:52,February 20, 2016,from
https://en.wikipedia.org/w/index.php?title=Mucosa
associated_lymphoid_tissue&oldid=698264357
2. Santacroce L. Academic lesson; 1997. Anatomy, physiology and surgical
pathophysiology of the MALT.
3. http://pathwaymedicine.org/malt-physiology
4. www.webmd.com/oral-health/picture-of-the-tonsils
5. http://www.web-books.com/eLibrary/Medicine/Physiology/Lymphatic/Lymphatic.htm
6. Adenoid. (2016, January 9). In Wikipedia, The Free Encyclopedia. Retrieved 11:38,
February 21, 2016,
from https://en.wikipedia.org/w/index.php?title=Adenoid&oldid=698967406
7. http://emedicine.medscape.com/article/1899367-overview
8. http://www.slideshare.net/pharmakingakash1/appendix-in-immunology
9. Pabst, R. and T. Tschernig, Bronchus-associated lymphoid tissue: an entry site for
antigens for successful mucosal vaccinations? Am J Respir Cell Mol Biol, 2010. 43(2): p.
137-41