In the 19th century, a young scientist from Germany discovered the heterogeneity of pancreatic tissue. Cells that differed from the main mass were located in small clusters, islets. Groups of cells were later named after the pathologist - islets of Langerhans (OL).

Their share in the total volume of tissues is no more than 1-2%, however, this small part of the gland performs its function, different from the digestive one.

Purpose of the Islets of Langerhans

The main part of the cells of the pancreas (PZh) produces enzymes that promote digestion. The function of island clusters is different - they synthesize hormones, so they are referred to as the endocrine system.

Thus, the pancreas is part of two main body systems - digestive and endocrine. Islets are microorganism that produce 5 types of hormones.

Most of the pancreatic groups are located in the tail of the pancreas, although chaotic, mosaic inclusions capture the entire exocrine tissue.

OLs are responsible for regulation carbohydrate metabolism and support the work of other endocrine organs.

Histological structure

Each island is a self-functioning element. Together they make up a complex archipelago that is made up of individual cells and larger formations. Their sizes vary considerably, from one endocrine cell to a mature, large island (>100 µm).

In pancreatic groups, a hierarchy of cell arrangements is built, there are 5 types of them, all perform their role. Each islet is surrounded by connective tissue, has lobules where capillaries are located.

Groups of beta cells are located in the center, along the edges of the formations are alpha and delta cells. How larger size islet, the more peripheral cells it contains.

The islets do not have ducts, the hormones produced are excreted through the capillary system.

cell types

Different groups of cells produce their own type of hormone, regulating digestion, lipid and carbohydrate metabolism.

1. Alpha cells. This group of OLs is located along the edge of the islets; their volume is 15–20% of the total size. They synthesize glucagon, a hormone that regulates the amount of glucose in the blood.
2. beta cells. They are grouped in the center of the islets and make up the bulk of their volume, 60-80%. They synthesize insulin, about 2 mg per day.
3. delta cells. Responsible for the production of somatostatin, they are from 3 to 10%.
4. Epsilon cells. The amount of the total mass is not more than 1%. Their product is ghrelin.
5. PP cells. The hormone pancreatic polypeptide is produced by this part of the OB. They make up to 5% of the islets.

Over the course of life, the proportion of the endocrine component of the pancreas decreases - from 6% in the first months of life to 1-2% by the age of 50.

Hormonal activity

The hormonal role of the pancreas is great.

The active substances synthesized in small islets are delivered by the bloodstream to the organs and regulate the metabolism of carbohydrates:

1. The main task of insulin is to minimize blood sugar levels. It increases the absorption of glucose by cell walls, accelerates its oxidation and helps to store it as glycogen. Violation of the synthesis of the hormone leads to the development of type 1 diabetes. In this case, blood tests show the presence of antibodies to beta cells. Type 2 diabetes develops when tissues become less sensitive to insulin.
2. Glucagon performs opposite function- increases sugar levels, regulates the production of glucose in the liver, accelerates the breakdown of lipids. Two hormones, complementing the action of each other, harmonize the content of glucose - a substance that ensures the vital activity of the body at the cellular level.
3. Somatostatin slows down the action of many hormones. In this case, there is a decrease in the rate of absorption of sugar from food, a decrease in the synthesis digestive enzymes a decrease in the amount of glucagon.
4. Pancreatic polypeptide reduces the amount of enzymes, slows down the release of bile and bilirubin. It is believed that it stops the consumption of digestive enzymes, keeping them until the next meal.
5. Ghrelin is considered the hunger or satiety hormone. Its production gives a signal to the body about the feeling of hunger.

The amount of hormones produced depends on the glucose received from food and the rate of its oxidation. With an increase in its amount, insulin production increases. Synthesis is triggered at a concentration of 5.5 mmol/l in plasma.

Provoke the production of insulin can not only eating. At healthy person the maximum concentration is observed during the period of strong physical stress, stress.

The endocrine part of the pancreas produces hormones that have a decisive effect on the entire body. Pathological changes in the OB can disrupt the functioning of all organs.

Video about the tasks of insulin in the human body:

The defeat of the endocrine part of the pancreas and its treatment

The cause of the defeat of the OL can be genetic predisposition, infections and poisonings, inflammatory diseases, immune problems.

As a result, there is a cessation or a significant decrease in the production of hormones by different cells of the islets.

As a result, it may develop:

1. SD type 1. It is characterized by the absence or deficiency of insulin.
2. SD type 2. It is determined by the inability of the body to use the hormone produced.
3. Gestational diabetes develops during pregnancy.
4. Other types of diabetes mellitus (MODY).
5. neuroendocrine tumors.

The main principles of the treatment of type 1 diabetes mellitus are the introduction of insulin into the body, the production of which is impaired or reduced. There are two types of insulin, fast and long-acting. The latter type mimics the production of pancreatic hormone.

Type 2 diabetes requires strict observance diet, moderate exercise and taking drugs that help burn sugar.

Diabetes is on the rise worldwide and is already being called the plague of the 21st century. Therefore, medical research centers are looking for ways to combat diseases of the islets of Langerhans.

Processes in the pancreas develop rapidly and lead to the death of the islets, which should synthesize hormones.

AT last years became known:

• stem cells transplanted to the pancreas tissue take root well and are able to produce the hormone in the future, as they begin to work as beta cells;
• OL produce more hormones if part is removed glandular tissue PZh.

This allows patients to abandon the constant use of drugs, a strict diet and return normal image life. The problem remains the immune system, which can reject transplanted cells.

Another possible way treatment considers transplantation from a donor part of the islet tissue. This method replaces the installation of an artificial pancreas or its complete transplantation from a donor. At the same time, it is possible to stop the progression of the disease and normalize blood glucose.

Successful operations have been performed, after which patients with type 1 diabetes no longer need to administer insulin. The body restored the population of beta cells, the synthesis of its own insulin resumed. Postoperatively, immunosuppressive therapy was administered to prevent rejection.

Video material about the functions of glucose and diabetes:

Medical institutes are working to study the possibility of transplanting a pancreas from a pig. The first drugs for the treatment of diabetes just used parts of the pancreas of pigs.

Scientists agree that it is necessary to study the features of the structure and work of the islets of Langerhans due to a large number important functions that carry out the hormones synthesized in them.

The constant intake of artificial hormones does not help to defeat the disease and worsens the patient's quality of life. The defeat of this small part of the pancreas causes profound disruption of the entire body, so research continues.

The pancreas - indeed unique organ on which the vital activity of all human body. And one of the main tasks of the pancreas is the regulation of the amount of sugar in the blood, due to the release of the hormone insulin. It is realized thanks to endocrine function especially the islets of Langerhans. What are these cells, what are their main features, and is it possible to transplant the endocrine cells of the islets of Langerhans to patients with type 1 diabetes?

Islets of Langerhans: structure and role for the pancreas

Each of the pancreatic islets of the pancreas, designed to perform an endocrine function, consists of groups of cells that are surrounded by capillaries. Interestingly, their mass and size is so minimal that there are about 1.5 - 2 million of them directly in the gland. The pancreatic islets of Langerhans are dispersed throughout the pancreas, however the largest number still located in the tail.

Despite the fact that the endocrine cells of the pancreas of this type perform one of the most important functions for the whole body, their total mass is no more than 1-2% of the total weight of the pancreas. Importantly, the pancreatic islets of Langerhans are represented by various types endocrine cells, which allows them to produce several hormones at the same time, thereby controlling metabolism.

Their basis is cells called insulocytes. So, A-cells are responsible for the production of glucagon, which make up about a quarter of all endocrine cell clusters present in this part of the organ. Most of the pancreatic cells are of the B-type, responsible for the production of insulin, which is why a violation in their work will lead to the onset of diabetes.

Secretion is provided by endocrine cells type D, as well as D1, the number of which is approximately equal to 10 percent of total. And, of course, the role of pancreatic PP cells is no less important, the number of which is small, but it is they who control the amount of pancreatic juice so that its excess or deficiency does not harm the work of the entire gastrointestinal tract.

Islets of Langerhans: endocrine function and antibodies to pancreatic cells

As you know, the main task of the pancreatic islets of Langerhans is to implement the endocrine function of the pancreas. First of all, this is the release of the main hormones called insulin and glucagon, aimed at controlling blood sugar levels. So, insulin reduces its amount if the indicators exceed the norm, and glucagon, on the contrary, increases it.

It is worth noting that in the event that the endocrine cells of the pancreatic islets do not cope with their work in full, and, accordingly, the hormones that the body needs are not released in the right amount, then the likelihood of diabetes is high. This disease occurs due to an excess of sugar in the body, and its treatment requires constant administration of insulin. Type 1 of this disease is especially dangerous, since in this case the endocrine cells of the pancreas are destroyed en masse, and, accordingly, the patient's condition worsens not gradually, but rapidly, and needs urgent and permanent treatment. There can be many reasons for this, for example, the production of antibodies against the background of immune diseases.

Importantly, there is a way to treat and restore the endocrine functions of the pancreas, by transplanting cells of the islets of Langerhans. But in this case, it will be necessary to pre-test for antibodies to pancreatic endocrine cells, since the transplant technique will be effective only for a certain type of diabetes. But with cancer or other ailments of the pancreas, it does not give the desired result.

Cell transplantation of the islets of Langerhans in patients with type 1 diabetes

To date, the islets of Langerhans provide an opportunity to treat type 1 diabetes, thanks to their transplantation. This method was discovered not so long ago by Canadian specialists, and although it requires very significant financial costs, and the procedure itself is incredibly complex and risky, but it is quite real and gives a chance for a gradual restoration of the endocrine function of the pancreas, and, accordingly, a possible deliverance for patients from a dangerous disease.

The essence of the transplant is that healthy endocrine cells obtained from a donor are introduced into the body of a person with type 1 diabetes using a catheter, as a result of which, gradually, due to their influence, the amount of insulin that is necessary to maintain blood glucose begins to be produced. within normal limits. It is important to understand that the islets of Langerhans for transplantation in patients with diabetes are removed only from a corpse that fully meets all the required parameters, which reduces the risk of rejection, especially since the antibodies present in the body are aimed at destroying foreign bodies. It is also important that the transplantation of endocrine cells of the pancreatic islets gives an effect quite quickly, and therefore, after a couple of weeks, the condition of a patient with type 1 diabetes rapidly begins to improve.

It is important to understand that transplantation of the islets of Langerhans is a risk that antibodies present in the body of a diabetic patient will lead to rejection of the pancreatic gland. That is why the success of the procedure plays an important role drug treatment, aimed at temporarily blocking the action of certain immune and antibody reactions that can lead to tissue destruction. At the same time, drugs for the treatment of the patient are selected in such a way that not completely, but only partially block certain immune reactions, in particular, those that produce antibodies to the cells of the islets of Langerhans, which made it possible to minimize the risk for the endocrine function of the pancreas.

In practice, the technique showed quite good results for patients, especially since there were no cases of death as a result of transplantation of pancreatic gland cells and their subsequent rejection under the influence of antibodies. Also, a certain number of sick patients no longer required the introduction of insulin at all, while some still needed it, however, most of the indicators related to the work of the endocrine function of the pancreas improved significantly, which made it possible to hope for a very favorable prognosis in the future.

However, it is worth noting that in this case there are certain disadvantages that must be taken into account. So, under the influence of antibodies to the islets of Langerhans, there is a high risk of all kinds of side effects, namely disorders in the production of pancreatic juice, diarrhea, dehydration, and more serious complications. In addition, even after the procedure, it is required throughout life to constantly take those drugs that are necessary so that the rejection of transplanted cells does not begin in the body. And due to the fact that these medicines are aimed at blocking immune reactions, in particular certain antibodies, their use increases the risk of all kinds of infections.

Thus, the islets of the pancreas perform an important endocrine function for the whole organism, providing the production of hormones necessary for metabolism and control of blood glucose levels. That is why for patients with type 1 diabetes, in some cases, transplantation of endocrine cell clusters may be relevant, which gradually normalizes the functioning of the body, and, accordingly, much-needed insulin is produced in the proper amount.

Each islet of Langerhans performs very, very important role for the whole organism. Its main role is to control the content of carbohydrates in the blood.

Discovery history

The islet of Langerhans was first described in 1869. The discoverer of these important formations located in the pancreas (mainly in its caudal part) was a young student - Paul Langerhans. It was he who first examined in a microscope an accumulation of cells, which in their morphological structure differed from other tissues of the pancreas.

Later it was found that the islets of Langerhans perform an endocrine function. This discovery was made by K. P. Ulezko-Stroganova. In 1889, for the first time, a link was established between the defeat of the islets of Langerhans and the development of diabetes mellitus.

What is the islet of Langerhans?

Currently this structure already well studied. It is now well known that this education has varieties. On the this moment the following are known:

It is thanks to this diversity that the cells of the islets of Langerhans perform all the duties that are assigned to them.

Alpha cells

This variety makes up approximately 15-20% of all available islets of Langerhans. The main task of alpha cells is the production of glucagon. This hormone has a lipid nature and is a kind of insulin antagonist. Once released, glucagon travels to the liver, where it binds to special receptors and regulates glucose production through the breakdown of glycogen.

beta cells

Islets of Langerhans of this variety are the most common. They make up about 65-80% of the total. It has now been established that their main function is to produce one of the most important hormones- insulin. This substance is a glucagon antagonist. It helps to activate the formation of glycogen and its storage in the cells of the liver and muscles. As a result this process there is a decrease in the number

delta cells

Islets of Langerhans of the pancreas of this type are not so common. They are only 2-10% of the total. Now them functional features well known. It has been established that these cells synthesize somatostatin. The function of this biologically active substance consists in suppressing the production of somatotropic, thyrotropic and somatotropin-releasing hormone. That is, it acts directly on the hypothalamus, as well as the anterior pituitary gland.

PP cells

Each islet of Langerhans of this type is involved in the production of a pancreatic polypeptide. Until the end, its function has not been studied. Currently, he is credited with the properties of suppressing the production of pancreatic juice. In addition, its effect helps to relax the smooth muscles of the gallbladder. In recent years, the dependence of the level of production of this substance on the formation of malignant neoplasms. As a result, it was found that during their development, the level of pancreatic polypeptide increases. So this biologically active substance can be considered a good marker of malignant neoplasms of the pancreas.

Epsilon cells

These islets of Langerhans are the rarest. Their number is less than 1% of the total. The main task of these cells is to produce a hormone called ghrelin. This active ingredient has large quantity functions, but its regulatory effect on appetite is most studied.

About the pathology of the islets of Langerhans

The defeat of these important structures has a very serious effect on the body. negative impact. In the event that antibodies are produced to the islets of Langerhans, the number of the latter progressively decreases. Damage to more than 90% of cells reduces insulin production to a critical level. low level. The result is the development of dangerous disease, as diabetes. Antibodies to cells of the islets of Langerhans appear more often in relatively young patients.

Serious damage to the population of these hormone-producing cells can cause an inflammatory process in the pancreas - pancreatitis.

How to save islet cells?

To do this, you have to take care of the entire pancreas as a whole. First of all, it is necessary to abandon excesses in alcoholic beverages. The fact is that they are among all food products has the most negative effect on the pancreas. When prolonged use alcoholic beverages a person develops and progresses pancreatitis, which over time can lead to significant damage to islet cells.

In addition to alcoholic beverages, a large amount of food rich in animal fats has a rather negative effect on the pancreas. In this case, the situation will be aggravated if, before the feast, the patient long time didn't eat anything.

In the event that there is already a chronic inflammatory process in the pancreatic tissue, it is necessary to contact a specialist - a general practitioner or a gastroenterologist. Doctors of these specialties will prescribe a rational course of treatment that can significantly slow down the development pathological changes. In the future, you will have to pass annually ultrasound procedure pancreas, which is performed in combination with other organs. In addition, it is necessary to take the content of amylase in it.

Determine the beginning of development chronic pancreatitis, in addition to laboratory and instrumental research the clinic will help. main symptom this disease is the occurrence. At the same time, this soreness has a shingles character and occurs more often after taking a large amount of food rich in animal fats. In addition, the patient after eating may be disturbed by a constant feeling. All these symptoms quickly leave him or reduce their severity while taking drugs containing pancreatin. Among them, the most popular medicines"Creon", "Mezim" and "Pancreatin". When inflammatory process in the tissue of the pancreas, it is better to completely abandon the use of alcohol. The fact is that even a small amount of it can aggravate the pathological process, thereby significantly harming this organ.

Functions of the pancreas.

I. Exocrine. It is secretion pancreatic juice- a mixture of digestive enzymes that enter the duodenum and break down all the components of the chyme;

II. Endocrine. It is the production of hormones.

Pancreas - parenchymal lobular organ.

The stroma of the gland is represented by a capsule that merges with the visceral peritoneum and trabeculae extending from it. The stroma is thin, formed by loose fibrous tissue. Trabeculae divide the gland into lobules. In layers of loose fibrous tissue there are excretory ducts of the exocrine part of the gland, vessels, nerves, intramural ganglia, lamellar Vater-Pacini bodies.

The parenchyma is formed by a combination of secretory sections ( acini), excretory ducts and the islands of Langerhans. Each lobule consists of exocrine and endocrine parts. Their ratio is ≈ 97:3.

Exocrine part of the pancreas is a complex alveolar-tubular protein gland. The structural and functional unit of the exocrine part is pancreaticacinus. It is formed by 8-14 acinar cells ( acinocytes) and centroacinous cells ( centroacinocytes). Acinar cells lie on the basement membrane, have a conical shape and pronounced polarity: the basal and apical poles differ in structure. The expanded basal pole is evenly stained with basic dyes and is called homogeneous. The narrowed apical pole is stained with acid dyes and is called zymogenic, because it contains granules of zymogen - proenzymes. At the apical pole of acinocytes there are microvilli. The function of acinocytes is the production of digestive enzymes. Activation of enzymes secreted by acinocytes normally occurs only in duodenum under the influence of activators. This circumstance, as well as enzyme inhibitors and mucus produced by the cells of the epithelium of the ducts, protect the pancreatic parenchyma from autolysis (self-digestion).

pancreas, lobule , drawing, high magnification:

1 - terminal section (acinus):

a - apical (oxyphilic) part of the cell, contains a zymogen,

b - basal (basophilic) - homogeneous part of the cell;

2 - hemocapillary;

3 - islet of Langerhans (insula).

Endocrine part of the gland. The structural and functional unit of the endocrine part of the pancreas is islet of Langergansa (insula). It is separated from the acini by a loose fibrous unformed tissue. The islet is made up of cells. insulocytes, between which lies loose fibrous connective tissue with hemocapillaries of the fenestrated type. Insulocytes differ in their ability to stain with dyes. In accordance with this, type A, B, D, D1, PP insulocytes are distinguished.

B cells (basophilic insulocytes) are stained in blue color basic dyes. Their number is about 75% of all cells of the islet. They are located in the center of the insula. The cells have a developed protein-synthesizing apparatus and secretory granules with a wide light rim. Secretory granules contain hormone insulin in combination with zinc. The function of B-insulocytes is the production of insulin, which lowers the level of glucose in the blood and stimulates its uptake by the cells of the body. In the liver, insulin stimulates the formation of glycogen from glucose. [With a lack of insulin production, diabetes mellitus is formed].

A-cells (acidophilic) - make up 20-25% of all cells of the islet. They are located on the periphery of the insula. They contain granules stained with acidic dyes. In an electron microscope, the granules have a narrow rim. Cells also contain a developed protein-synthesizing apparatus and secrete a hormone glucagon . This hormone is an insulin antagonist (contrinsular hormone), as it stimulates the breakdown of glycogen in the liver and increases blood glucose levels.

D-cells make up about 5% of the endocrine cells of the islet. They are located on the periphery of the insula. Contains moderately dense granules without a light rim. The granules contain a hormone somatostatin, which inhibits the function of A, B-cells of islets and acinocytes. It also has a mitosinhibitory effect on various cells.

D1-cells contain granules with a narrow rim. Work out vasointestinal polypeptide, lowering blood pressure and stimulating the production of pancreatic juice. The number of these cells is small.

PP cells(2-5%) are located on the periphery of the islets, sometimes they can also be found in the exocrine part of the gland. They contain granules of various shapes, densities and sizes. Cells produce pancreatic polypeptide which inhibits the exocrine activity of the pancreas.

one of enough common causes The development of diabetes is an autoimmune process, while the body produces antibodies to the cells of the islets of Langerhans, namely those that produce insulin. This causes their destruction and, as a result, a violation of the endocrine function of the pancreas with the development insulin dependent diabetes 1 type.

What are the islets of Langerhans?

The entire gland is divided into structural units, the so-called islands. An adult and physically healthy person has about 1 million of them. Most of these formations are located in the tail part of the organ. Each of these pancreatic islets is complex system, a separate functioning organ with microscopic dimensions. All of them are surrounded by connective tissue, which includes capillaries, and are divided into lobules. Antibodies produced in diabetes mellitus most often injure its center, since there is an accumulation of beta cells.

Varieties of formations

The islets of Langerhans contain a set of cells that perform vital functions for the body, namely maintaining normal level carbohydrates in the blood. This is due to the production of hormones, including insulin and its antagonists. Each of them includes the following structural units:

• alpha;
• beta cells;
• delta;
• pp cells;
• epsilon.

The task of alpha and beta cells is the production of glucagon and insulin.

The main function of the active substance is the secretion of glucagon. It is an antagonist of insulin, and thus regulates its amount in the blood. The hormone performs its main function in the liver, where it controls the production the right amount glucose, by interacting with a specific type of receptor. This is due to the breakdown of glycogen.

The main goal of beta cells is the production of insulin, which is directly involved in the process of storing glycogen in the liver and skeletal muscles. Thus, the human body creates energy reserves for itself in case prolonged absence receipts nutrients. The mechanisms for the production of this hormone are launched after eating, in response to an increase in the amount of glucose in the blood. The considered cells of the islets of Langerhans make up the bulk of them.

Delta and PP cells

This variety is quite rare. Delta cell structures make up only 5-10% of the total. Their function is to synthesize somatostatin. This hormone directly suppresses the production of somatotropic, thyrotropic and somatotropin-releasing hormone, thus affecting the anterior pituitary and hypothalamus.

In each of the islets of Langerhans, a pancreatic polypeptide is secreted, this process occurs in pp cells. The function of this substance is not fully understood. There is an opinion that it suppresses the production of pancreatic juice and relaxes the smooth muscles of the gallbladder. In addition, with the development of malignant neoplasms, the level of pancreatic polypeptide increases sharply, which is a marker of the development oncological processes in the pancreas.

Epsilon cells

Human appetite is controlled by the hormone ghreelin, which is produced by Epsilon cells.

The indicators are less than 1% of all the structural units that are in the islets, but because of this, the cells are even more important. The main function of these units is the production of a substance called grilin. The action of this biologically active ingredient manifested in the regulation of human appetite. An increase in its amount in the blood causes a feeling of hunger in a person.

Why do antibodies appear?

Human immunity defends itself against foreign proteins by developing weapons that are activated only against a specific substance. This method of countering the invasion is the production of antibodies. But sometimes this mechanism fails and then own cells, and in diabetes they are beta, act as a target for antibodies. As a result, the body destroys itself.

The danger of developing antibodies to the islets of Langerhans?

An antibody is a specific weapon only against a specific protein, in this case the islets of Langerhans. This leads to the complete death of beta cells and to the fact that the body will spend its immune forces on their destruction, ignoring the fight against dangerous infections. After that, insulin completely stops being produced in the body and without its introduction from the outside, a person will not be able to absorb glucose. Eating normally, he can even die of hunger.

Who is eligible for testing?

Obese people must be tested for antibodies.

Studies on the presence of a disease such as type 1 diabetes in humans are carried out for people with obesity, as well as for those who have at least one of the parents already have this disease. These factors increase the likelihood of developing pathological process. It is worth taking tests for the presence of people suffering from other diseases of the pancreas, as well as those who have suffered injuries to this organ. Some viral infections start the autoimmune process.