histology is the science that studies tissues: a set of cells similar in structure and function, it is a level of cellular organization assigned to
play a certain role within an organism. is closely linked to other branches such as:
- cytology: studies cellular structure
- pathological anatomy: studies histology for diagnostic purposes
- physiology: mechanisms of regulation and response of organisms
- embryology: tissue formation and embryonic processes
to distinguish and analyze the various tissues, the microscope is used which allows observation in detail and distinguishing the various
structures.
The tool varies according to the size of what I want to observe. The ability of the optical system to detect very small details is called
resolution power, it allows us to distinguish the details of extremely small structures in a very clear way.
optical microscope (micrometers -6) allows us to have an optimal resolving power. the complex lens system is referred to as an objective.
the maximum magnification level is 100x.
The minimum distance at which two points are seen as distinct is called the resolution limit.
The ability to zoom in on the image is a secondary feature to the resolution.
Lens and eyepiece work together to resolve the image (the eyepiece resolves the actual image resolved by the lens)
the different microscopes can operate with:
- bright field based on the property of the cell to absorb or scatter light, the samples must be stained
- darkfield (bright and dark differ by light source)
- phase contrast: allows you to observe live cells and samples, the light comes from below and allows you to observe live cells without dyes.
How are fabrics studied and observed?
block the autolysis process
- biopsy: taking a sample of an organ
objective: what I see on the slide must respect as much as possible the morphology that the tissue has in its biological location.
there must be no putrefaction process so I perform the...
- fixation (blocking the autolysis process) which can be chemical or physical
you have to set up the organic preparations
- arrange thin sections so that the light can pass through them. the tissue must be hard (with the fixation I make the sample hard in a
chemical way: I remove water, i.e. dehydrate and impregnate with paraffin wax)
- to make it visible I need dyes
I choose the coloring based on my study objective and the structures I want to detail and observe (e.g. I want to identify cell architecture)
dyes are divided into salts and acids/bases, the most important are:
- eosin affinity for basic structures (cytoplasm)
- hematoxylin affinity for acidic structures (nucleic acids and nuclei)
to identify other details there are other colors (e.g. membrane black) (base membrane fuchsia) (bacteria blue)
the different types of cells arrange and organize themselves to form 4 basic types of tissue:
1. EPITHELIUM OR EPITHELIAL TISSUE
the cells are very close, connected in various ways and immersed in a very scarce extracellular substance, they form cellular laminae or
solid clusters and rest on a basement membrane that separates it from the connective tissue, they are found on all internal and external
covering surfaces.
Epithelia cover the external and internal surfaces of the body (lining epithelia), line the internal surfaces of blood and lymphatic vessels,
form glands (glandular epithelia) performing different functions in relation to their different locations.
Epithelia are NOT vascularized and receive nutrients by diffusion from capillaries located in the surrounding connective tissue.
Epithelial tissue arises from all three germ layers:
from the ectoderm: the epidermis, which covers the external surface of the body, the epithelium of the cornea and the epithelium of the
mucosa which lines the oral cavity originate; the sebaceous and sweat glands attached to the skin and the mammary glands.
from the endoderm: formation of the epithelium of many of the mucous membranes that cover the internal surface of body cavities
communicating with the outside (for example, stomach, intestine, etc.) and give rise to the related glands (liver, pancreas, gastric glands
and intestinal, etc.)
from the mesoderm: the epithelium lining most of the urinary and genital tracts, the epithelium of the adrenal cortex and the epithelium lining
the ovary and serous cavities (pleura, pericardium and peritoneum) originate. The latter is commonly indicated with the term mesothelium;
the epithelium that lines blood and lymph vessels internally, called the endothelium.
COATING EPITHELIUM .
in most cases they are tissues that line the surfaces, cavities and ducts of the body.
It covers the external surfaces and the body cavities (tissue side, in contact with the underlying connective tissue), it also covers the luminal
side (side in contact with the organ cavity)
made up of laminae. one or more layers separated by poor matrix. cell junctions provide exchange mediation and mechanical strength.
They rest on a shared structure called the basement membrane which provides anchorage, separates from the underlying connective tissue
and regulates metabolic exchanges between connective tissue and epithelium.
Epithelia depend on the diffusion of oxygen and metabolites from the underlying tissues as they are not vascularised
They form a protective waterproof barrier.
play a certain role within an organism. is closely linked to other branches such as:
- cytology: studies cellular structure
- pathological anatomy: studies histology for diagnostic purposes
- physiology: mechanisms of regulation and response of organisms
- embryology: tissue formation and embryonic processes
to distinguish and analyze the various tissues, the microscope is used which allows observation in detail and distinguishing the various
structures.
The tool varies according to the size of what I want to observe. The ability of the optical system to detect very small details is called
resolution power, it allows us to distinguish the details of extremely small structures in a very clear way.
optical microscope (micrometers -6) allows us to have an optimal resolving power. the complex lens system is referred to as an objective.
the maximum magnification level is 100x.
The minimum distance at which two points are seen as distinct is called the resolution limit.
The ability to zoom in on the image is a secondary feature to the resolution.
Lens and eyepiece work together to resolve the image (the eyepiece resolves the actual image resolved by the lens)
the different microscopes can operate with:
- bright field based on the property of the cell to absorb or scatter light, the samples must be stained
- darkfield (bright and dark differ by light source)
- phase contrast: allows you to observe live cells and samples, the light comes from below and allows you to observe live cells without dyes.
How are fabrics studied and observed?
block the autolysis process
- biopsy: taking a sample of an organ
objective: what I see on the slide must respect as much as possible the morphology that the tissue has in its biological location.
there must be no putrefaction process so I perform the...
- fixation (blocking the autolysis process) which can be chemical or physical
you have to set up the organic preparations
- arrange thin sections so that the light can pass through them. the tissue must be hard (with the fixation I make the sample hard in a
chemical way: I remove water, i.e. dehydrate and impregnate with paraffin wax)
- to make it visible I need dyes
I choose the coloring based on my study objective and the structures I want to detail and observe (e.g. I want to identify cell architecture)
dyes are divided into salts and acids/bases, the most important are:
- eosin affinity for basic structures (cytoplasm)
- hematoxylin affinity for acidic structures (nucleic acids and nuclei)
to identify other details there are other colors (e.g. membrane black) (base membrane fuchsia) (bacteria blue)
the different types of cells arrange and organize themselves to form 4 basic types of tissue:
1. EPITHELIUM OR EPITHELIAL TISSUE
the cells are very close, connected in various ways and immersed in a very scarce extracellular substance, they form cellular laminae or
solid clusters and rest on a basement membrane that separates it from the connective tissue, they are found on all internal and external
covering surfaces.
Epithelia cover the external and internal surfaces of the body (lining epithelia), line the internal surfaces of blood and lymphatic vessels,
form glands (glandular epithelia) performing different functions in relation to their different locations.
Epithelia are NOT vascularized and receive nutrients by diffusion from capillaries located in the surrounding connective tissue.
Epithelial tissue arises from all three germ layers:
from the ectoderm: the epidermis, which covers the external surface of the body, the epithelium of the cornea and the epithelium of the
mucosa which lines the oral cavity originate; the sebaceous and sweat glands attached to the skin and the mammary glands.
from the endoderm: formation of the epithelium of many of the mucous membranes that cover the internal surface of body cavities
communicating with the outside (for example, stomach, intestine, etc.) and give rise to the related glands (liver, pancreas, gastric glands
and intestinal, etc.)
from the mesoderm: the epithelium lining most of the urinary and genital tracts, the epithelium of the adrenal cortex and the epithelium lining
the ovary and serous cavities (pleura, pericardium and peritoneum) originate. The latter is commonly indicated with the term mesothelium;
the epithelium that lines blood and lymph vessels internally, called the endothelium.
COATING EPITHELIUM .
in most cases they are tissues that line the surfaces, cavities and ducts of the body.
It covers the external surfaces and the body cavities (tissue side, in contact with the underlying connective tissue), it also covers the luminal
side (side in contact with the organ cavity)
made up of laminae. one or more layers separated by poor matrix. cell junctions provide exchange mediation and mechanical strength.
They rest on a shared structure called the basement membrane which provides anchorage, separates from the underlying connective tissue
and regulates metabolic exchanges between connective tissue and epithelium.
Epithelia depend on the diffusion of oxygen and metabolites from the underlying tissues as they are not vascularised
They form a protective waterproof barrier.
