Somatic Cells: Different Types Of Somatic Cells And The Difference Between Somatic Cells, Germ Cells, And Gametes

Somatic cells, similarly to germ cells, are two basic types of cells that are commonly found in animals.  Somatic cells form through a process called mitosis, which is a type of asexual reproduction.

Germ cells, on the other hand, form by a process called meiosis, a type of sexual reproduction. 

Somatic cells are also called vegetal cells. The biggest difference between germ cells and somatic cells are germ cells produce haploid gametes, which reproduce sexually, whereas somatic cells build the body of multicellular animals. 

Somatic cells make up all cells of the human body apart from sperm cells or egg cells. They make up all parts of the body including skin cells, liver cells, bone cells, and more. Mature somatic cells are able to perform specialized functions.

What Are Germ Cells?

Germ cells give rise to an organism’s gametes. Germ cells originate from the embryo and then migrate through towards the gonads through the gut.

Germ cells of angiosperms are found within the floral meristem. The plant germ cells then develop further prior to the embryonic development. Sperm cells are the male gamete and egg cells or ovum are the female gamete. 

Multicellular organisms go through sexual reproduction by the fusion of male and female gametes. 

Gametes are haploid cells, which reproduce by meiosis of diploid germ cells. Germ cells can be found in the gonads of both males and females.

In the case of males, germ cells are found in the testes, whereas in females they can be found in the ovaries.  

The process of germ cells forming gametes is a process called gametogenesis. Germ cells can go through meiosis and mitosis when producing gametes. The cells that germ cells produce to form gametes are called germline.  

Oogenesis is the process of producing female gametes or egg cells from germ cells. On the other hand, spermatogenesis is the production of the male gamete or sperm cells.

The production of sperm cells involves meiotic division, which creates four equal spermatids.  In the process of producing egg cells, the meiotic genesis is asymmetrical, meaning that one egg cell forms alongside three polar bodies.  

In the production of sperm cells, involves fast and uninterrupted cell divisions, whereas the production of egg cells is interrupted until puberty.  

Mutations in germ cells can be passed down through generations because germ cells produce gametes, which reproduce sexually.  

What Are Somatic Cells?

Somatic cells are what make up the human body,  generally speaking.

The somatic cells found in the human body are mostly diploid cells, and they produce asexually through mitosis, meaning that two sets of homologous chromosomes are in the nucleus of each somatic cell.  

Some species may have polyploid or haploid somatic cells. Polyploid somatic cells can typically be seen in plants.

In humans, on the other hand, the fusion of a sperm cell and an egg cell forms a diploid zygote, which then develops into a multicellular organism by way of mitotic division.  

In an adult human, there are over three million somatic cells in total. These somatic cells can be categorized into four main types of tissue found in the human body. These four categories are connective tissue, muscle tissue, epithelial tissue, and nerve tissue. 

If a mutation occurs in a somatic cell, they will not have any contribution to the evolution of the cell as they do not reproduce sexually.  

Somatic cells get their name from the Greek word “Soma”, meaning the body. There are over 220 different types of somatic cells found in the human body.  Here is an overview of some of the main somatic cells found in the human body. 

Bone Cells

Bone cells consistently get replaced with newer bone cells. There are two main types of bone cells, which are osteoblasts and osteoclasts.  The former forms bone and maintains them, whereas the latter dissolves or resorbs old bone cells.  

Osteoblasts are square shaped cells that make up proteins to form bones. They are able to communicate with each other and produce other molecules including growth factors, which causes the growth of the bones.  

Osteoclasts are big cells with multiple nuclei. Once the osteoblast or osteoclast have done their job, they undergo a process called apoptosis, which is the programmed death of the cell. 

Muscle Cells

Muscle cells are also called myocytes, which are long, tubular cells. Myocytes come in three types, which make up the three types of muscle; skeletal muscle, cardiac muscle, and smooth muscle.

Skeletal muscles attach to bones, allowing the body to move. Cardiac muscle are found in the heart, and they are responsible for the heart pumping blood.  Smooth muscle is what lines the internal organs, including the digestive tract, uterus, and the bladder.  

Since myocates are very different from other types of cells found in the body, the different parts of myocytes have their own particular terminology.

The cell membrane of myocytes is called the sarcolemma, the mitochondria are known as sarcosomes, and finally the term for the cytoplasm is sarcoplasm.  

The part of the cell that is responsible for muscle movement is called the sarcomere, which forms long chains which are called myofibrils.  These myofibrils run throughout each of the muscle fibers.  

Muscle cells do not have the ability to divide and form new cells.  Because of this fact, babies have a higher number of myocytes than adults. 

Nerve Cells

Another name for nerve cells are neurons. They can be found all throughout the human body, but they are particularly dense within the spinal cord and the brain.

The function of neurons is to send and receive messages or signals to and from other neurons or organs by way of electrical or chemical signals.  

Neurons stay at a certain electrical voltage, and if this voltage changes, it makes an electrochemical signal known as an action potential.

Once an action potential happens in a neuron, it releases neurotransmitters, which are a type of chemical that can affect targeted cells.  A few examples of neurotransmitters include histamine, epinephrine, serotonin, and dopamine.  

The structure of neurons is unique to them.  The parts of a neuron include the dendrites, axon, and the soma.  The soma creates the body of the cell which includes the nucleus.

The axon is the part of the cell that transmits electrical impulses.  Dentrites are about to fan out around the soma to receive electrochemical impulses from other neurons.  Neurotransmitters are released from the ends of the axon, where the axon terminals exist. 

Blood Cells

The blood cells are also known as hemocytes or hematopoietic cells.

Blood cells are made in three main types, including thrombocytes or platelets (yellow blood cells), leukocytes (white blood cells), and erythrocytes (red blood cells). Blood is composed of these cells and plasma.  

The function of erythrocytes is to transport oxygen to cells through the molecule hemoglobin, and they also collect carbon dioxide from cells.  They comprise between 40 – 45% of the blood’s total volume.

Around a fourth of the cells found in the human body are erythrocytes. They have a lifespan of approximately 100 to 120 days.  When these cells mature, they no longer have nuclei.  

Leukocytes’ main function is to defend the body against outside substances such as viruses and bacteria.  Their lifespan is only around 5 days.  

Platelets are tiny fragments of cells that promote the clotting of the blood once an injury occurs.  They, too, have a short lifespan, only living between five and nine days.  

Epithelial Cells

Epithelial cells include a few different types of cells that comprise the epithelial tissues.  They line various organs such as the skin, blood vessels, and the digestive tract to name only a few.

Epithelial cells have the ability to perform many different functions, depending on the particular type of epithelial cell. These functions include secretion and excretion, among others. The following are some examples of epithelial cells.

Squamous Cells

Squamous cells have a thin, flattened shape, and they have a small nucleus in their center, in addition to lots of cytoplasm. Compared to the nuclei in other cells, the nuclei of squamous cells looks flattened and has an elliptical shape.  

Squamous cells can be discovered in various parts of the body including the epidermis, capillaries, the urethra and the air sacs inside the lungs.  Since these cells get exposed to the outside environment, these cells get replaced constantly. 

Cuboidal Cells

As the name would suggest, cuboidal cells have a cube-like shape.  Along with the cell organelles, cuboidal cells feature secretory vesicles in addition to microvilli. 

Cuboidal cells are typically found in body parts with high metabolic activity, where these cells secrete and exchange a range of different substances.  They can be discovered in ducts, tubules, and neural retina, among other places in the human body. 

Columnar Cells

As the name would suggest, columnar cells form in an elongated shape. Some columnar cells are ciliated, and they also secrete and absorb various substances.

These cells can be discovered within the fallopian tubes, in addition to various parts of the digestive tract and the respiratory system. 

Connective Tissue Cells

Connective tissue is very abundant and widespread throughout the body. Connective tissue cells have many essential functions including binding in addition to providing protection and support.

For this reason, there are multiple types of connective tissue cells that have specialized functions. The two main types of connective tissue cells are resident cells and transient cells.  These can be subdivided into further subcategories of cell. 

Resident Cells

Resident cells are connective tissue cells that are fixed in place and therefore cannot migrate from one place to another. These are some examples of resident connective tissue cells.

Fibroblasts 

The most common type of connective tissue cell are fibroblasts.  They have are shaped like a spindle, and they also have a flattened nucleus.

As they are among the most abundant connective tissue cells, they can be found within the interstital spaces in multiple organs in the human body. 

Since fibroblasts are indeed resident cells, they stay fixed in place in their particular regions of organs such as the lungs, kidneys, and the liver.

Fibroblasts produce substances such as laminins, collagen, fibronectin, and prostanglandins, just to name a few.  They play an essential role in healing wounds and reorganizing the extracellular matrix. 

Macrophages

Macrophages are resident cells that come from erythomyeloid progenitors, and they exist in tissue in  which they comprise the mononuclear phagocyte cellular system. 

Within the human body, macrophages react to pathogenic invasions.  They are responsible for ingesting these invasive organisms in addition to damaged cells.

After tissue macrophages have been depleted, the levels of collagen and hyaloronan increase. This shows that macrophages are essential in extracellular matrix homeostasis. 

Adipocytes

Adipocytes are fat cells, and they are connective tissue cells from the mesenchymal stem cells.  They have a big droplet near the center of the cell, much like other cell organelles. In this section of the cell, triglycerides (fats) are stored.  

Once the fat content in the human body increases, the amount of these droplets also increases inside the cell.  However, they do not decrease once the fat content decreases.

Other than fat storage, adipocytes also generate energy and regulate the body temperature. 

Mast Cells

Mast cells can be found within the mucosal or epithelial tissues.  They are oval shaped, and they originate from bone marrow before they migrate to loose connective tissue.

They also feature basophilic granules which produce heparin and histamine.  Once histamine is released, the cell junctions weaken, allowing cells and proteins to go inside the connective tissues. 

Transient Cells

Transient cells, as opposed to resident cells, transient cells in connective tissue have the ability to migrate from the bloodstream to affected sites. For this reason, transient cells make up various parts of the immune system, including the following. 

Neutrophils

In the human body, neutrophils make up approximately 60% of all leukocytes, or white blood cells. These cells are the first to respond to inflammatory sites, and they are responsible for defending the body against fungus and bacteria, among other microorganisms.  

Eosinophils

Eosinophils have a bilobed nucleus with big cytoplasmic granules.  They are associated with allergic reactions, in addition to warding off multicellular organisms. 

Basophils

Basophils comprise 0.5 – 1% of the all the leukocyte cells, and they are typically bigger than other granulocytes.

As they are granulocytes, they have granules responsible for the production of enzymes that are associated with allergic reactions.  Additionally, they play an important role in the process of the clotting of blood.

Monocytes 

Monocytes are big cells that can produce both macrophages or dendritic cells.  They are responsible for the removal of damaged cells, though a process called phagocytosis.

Additionally, monocytes are associated with fighting infections, in addition to the regulation of the immune system. 

Plasma Cells

Plasma cells are also called B cells, and they produce antibodies when responding to antigens.  This process allows the B cells to identify antigens and then destroy them.

Location Somatic Cells

As discussed previously, somatic cells can perform specialized functions, depending on which type of cell and which part of the body they can be found.

Below are some of the specific locations where various types of somatic cells can be found.

Epithelial Tissue Cells

Squamous Epithelial Cells

Squamous epithelial cells are responsible for secreting lubricant in addition to allowing certain substances to pass through.  

These cells can be found in parts of the body that are associated with these particular functions, which includes the blood vessels, lymphatic vessels, alveoli, in addition to the serous membrane which lines the surface of internal organs and body cavities.

Stratified squamous epithelial cells are comprised of many layers of flat cells in addition to basal layers of cuboidal or columnar cells. 

They are essential for protection against abrasions, and because of this they can be found on parts of the body that get exposed to the external environment, such as the skin and mouth cavity, among others. 

Cuboidal Epithelial Cells

Cuboidal epithelial cells have cube-like shape, and they also excrete and absorb different substances.

Simple cuboidal epithelial cells feature only one layer of cells, and can be found in the secretory body parts including the small glands as well as the surface of the ovaries in addition to the renal tubules and sections of the thyroid. 

Stratified cuboidal epithelial cells are found on the surfaces of excretory ducts including the sweat glands and sections of the kidney tubules.

Columnar Epithelial Cells

Simple columnar epithelial cells are also used for the secretion and absorption of substances, but mainly they are essential for the movement of mucous.

Because of this, they can be found within sections of the digestive tract, in addition to many parts of the female reproductive tract such as the uterine cervix, minor ducts, and the fallopian tubes. 

Stratified columnar epithelial cells can be found within the conjunctiva in addition to parts of the anus, pharynx, uterus, among others. 

Processes Of Production

Simply put, all cells in the human body originate from three germ layers, which are ectoderm, mesoderm, and endoderm. Mesodermal cells create connective tissue, lymph vessels, and the gonads among others.

Ectodermal cells make up the cells of the central nervous system, in addition to the epidermis and the peripheral nervous system, and more.

Ectodermal cells, on the other hand, make up the cells in the respiratory system, the bladder, pancreas, and the thyroid among others.  

Once developed inside an embryo, stem cell descendants known as progenitor cells produce various types of cells, and they are found in multiple parts of the human body. 

Below are some of the different processes involved in producing various types of somatic cells. 

Hematopoietic Progenitor Cells

Inside bone marrow and peripheral blood, hematopoietic progenitor cells can be found.  These cells can then differentiate to produce specialized blood cells such as red blood cells, white blood cells, and platelets.  

For the production of functional, mature cells, hematopoietic progenitor cells first must divide in order to produce multipotent progenitor cells, such as common myeloid stem cells and lymphoid stem cells. 

The needs of the body will determine what type of cells are produced. If the body is experiencing hypoxia, a growth factor called erythropoietin will produce inside the kidneys to stimulate the production of red blood cells. 

When hormones are present in the body, myeloid stem cells go through many stages of division in order to produce more red blood cells.

Interleukin 3 and 5, in addition to granulocytic and agranulocytic colony-stimulating factors are signal molecules that have an influence on the production of granulocytes and monocytes derived from myeloid stem cells.

Some leukocytes are able to divide through mitosis, whereas red blood cells which don’t have a nucleus cannot. 

Neural Progenitor Cells

One of the other main types of progenitor cells found in the human body are neuronal progenitor cells.  These types of cells can be found in the brain and the lateral ventricle in addition to the striatum.

In humans, these cells create glial cells.  For example, inside the subventricular zone, neural progenitor cells are able to divide through mitotic division and create quiescent or proliferative B1 cells. 

These types of cells can divide asymmetrically and create B1 cells that have the ability to self-renew in addition to transient progenitor cells that can create C cells. 

Endothelial Progenitor Cells

Endothelial progenitor cells are another type of stem cells that can be found inside bone marrow.  These cells become activated by the production of particular cytokines, just like red blood cells. 

These cells can be produced during injuries, and they can have an influence on the mobilization of progenitor cells towards the affected area. These cells then get stimulated to divide and produce endothelial cells to replace damaged or lost cells. 

Some somatic stem cells include the following:

• Mesenchymal stem cells
• Mammary stem cells
• Intestinal stem cells
• Olfactory adult stem cells 

What Are The Differences Between Gametes And Somatic Cells?

Somatic cells divide through the process of mitosis. They feature two copies of each chromosome, one from each parent. These types of cells with two copies of each chromosome are known as diploid cells.  

Sperm cells and egg cells are called gametes. These types of cells are formed by a process called meiosis, which is a process in which cells divide with only a single copy of each chromosome.

The name for these sorts of cells is haploid. Gametes are haploid cells since a sperm and an egg fuse together during fertilization in order to make a new organism that has diploid cells. 

When mutations occur in somatic cells, it only affects a single organism, and it is not passed onto the offspring.  When a mutation occurs in a gamete, on the other hand, it can affect the offspring.

Once gametes fuse, they become the first somatic cell of the offspring, which then divides, thus developing and forming all of the offspring’s somatic cells. 

To reiterate, mutations in somatic cells will not have an effect on the next generation, whereas mutations in gametes will be passed on to the next generation.

For example, when a big mutation happens in a gamete such as an extra chromosome inside a fertilized egg, the somatic cells that divide from the fertilized egg will also have that extra chromosome.  This can result in Down Syndrome in humans. 

What Are The Differences Between Somatic Cells And Germ Cells

Somatic cells and germ cells alike can be found in most animals, including humans.  They share a lot of characteristics, but there are multiple differences in respect to their functions. 

As previously discussed, somatic cells make up all the cells in the body apart from gametes (sperm or egg cells). Sperm and egg cells are not somatic cells, but germ cells are considered precursors of gametes.  

In the early stages of development for many organisms, these types of cells have been shown to separate from somatic cell lineages, and they migrate to the developing gut.

Once there, the main difference between somatic and germ cells is that somatic cells are fully functional, whereas germ cells are progenitor cells that create functional cells. 

Another main difference between somatic cells and germ cells are the location of the cells.  Since germ cells give rise to gametes, they can be found solely in the gonads (testes in males and ovaries in females). 

Somatic cells are found throughout the body.   Not only in tendons and ligaments, but the cells that create connective tissue can be found inside the fibrous coverins of membranes.

Thus, they can also be found in various sections of the reproductive system; for example, the cells of the connective tissue surrounding the oogonia. 

Germ cells, much like somatic cells, can divide through the process of mitosis.  Because of this, they are the sole cells in the body that undergo both mitosis and meiosis. Mitosis is especially significant in germ cells, as it allows germ cells to multiply. 

It’s important to note that somatic cells and germ cells alike are diploid, meaning they have 46 chromosomes in total in humans.  Because of this, mitosis allows them to increase the amount of diploid cells in the gonads.

To create gametes, the cells must go through meiosis which creates haploid cells, for example, sperm cells with 23 chromosomes. 

Diploid somatic cells only divide through mitosis. The cell division of somatic cells is essential for growth and replacing lost and damaged cells, which is not the case in germ cells. 

Germ cells multiply through the process of mitosis in order to increase the amount of diploid cells inside the gonads.  Meiosis makes sex cells that can form new organisms.  

The Division Of Somatic Cells

Somatic cells divide by mitosis, which is a form of cell division that makes two identical daughter cells that have identical characteristics.  

This type of division has four crucial stages which include the following.

Prophase

In the prophase stage of cell division, the chromosomal pairs condense and compact.  Here, sister chromatids join together in the centromere. 

Metaphase 

The metaphase stage of division is where the nuclear membrane breaks down as the spindle fibers move to opposite sides of the cell.  At the end of the metaphase, the fibers begin to align with the chromatids at the equatorial plane of the somatic cell.

Anaphase 

During this stage of the cell’s division, the contracted fibers of the spindle separate the sister chromatids and then pulls them to the opposite sides of the cell, ensuring that each daughter cell will have the exact same number of chromosomes. 

Telophase 

The final stage of division involves the nuclear membrane forming around the separated chromosomes.  Finally, the cytoplasm divides by a process called cytokinesis, ultimately separating both daughter cells entirely. 

The Advantages Of Somatic Cells

Somatic cells comprise all the different organs and tissues of the body.  For this reason, they are essentially important for the various functions of all the vital organs, in addition to the connective tissue and bones just to name a few. 

The specialization of these types of cells ensures that they can work synergistically to perform their essential functions.

The division of these cells occurs through the process of mitosis, which makes sure that they are consistently replaced when an injury occurs or the old cells die.  This cell division also allows the organism as a whole can grow over time.  

The Similarities Between Somatic Cells And Germ Cells 

Germ cells and somatic cells, along with stem cells collectively comprise the bodies of multicellular organisms, including human beings.  Both germ cells and somatic cells in humans are diploid.

Therefore, there are two sets of homologous chromosomes found in every somatic cell and germ cell.   Both types of cell have the ability of differentiating into specific types of cells. 

The Differences Between Somatic Cells And Germ Cells 

Somatic cells comprise a myriad of different cells in a multicellular organism, besides cells that produce gametes, or gametes themselves (sperm cells and egg cells). Germ cells, on the other hand, are a type of cell that produces gametes or reproductive cells.  

There are various types of somatic cells that are found in different types of tissues within the body of a multicellular organism, including human beings.

The specific type of somatic cell and the location of the cell within the body determines what functions the cell is capable of performing. Germ cells only produce either male or female gametes. 

The vast majority of cells found in multicellular organisms, including human beings, are somatic cells.  Germ cells are much less abundant in multicellular organisms in comparison. 

Somatic cells are capable of performing a myriad of different functions within a multicellular organism, whereas germ cells are only capable of producing gametes for sexual reproduction. 

Somatic cells divide by the process of mitosis, whereas germ cells go through the process of meiosis.  Similarly, somatic cells reproduce asexually, whereas germ cells participate in sexual reproduction. 

When mutations occur in somatic cells, the mutations are not passed onto the next generation, whereas mutations in germ cells do get passed on through the next generation.

Similarly, somatic cell mutations do not have any effect on evolution, whereas the mutations in germ cells do have an effect on evolution. 

Conclusion

Somatic cells and germ cells are both found in multicellular organisms, but somatic cells are much more abundant, and they form the building blocks of multicellular organisms like human beings.

Diploid germ cells create haploid gametes by the means of meiotic cell division.  The vast majority of cells in multicellular organisms are, in fact, somatic cells.

Somatic cells reproduce asexually, and they turn into a myriad of different types of cells depending on their, such as tissues, organs, and organ systems.

Depending on the type of somatic cell, they are able to perform specialized functions.  Both types of cells are essential for the lives of multicellular organisms, including human beings. 

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