Welcome to lab classes in basic histology Introducing lab class (in spanish) .

The aim of these lab classes is to provide students with educational resources to acquire basic practical skills of each subject, recognize, locate and describe cell types and basic tissues.

Each of these practical sessions are structured around three main elements:
- Definition of learning objectives.
- Description of basic tissues and their cell types.
- Exercices location of cell types and basic tissues in virtual slides.

LEARNING OBJECTIVES
- Understand that the adipose tissue is a specific connective tissue.
- Differentiate between adipose tissue and the other types of connective tissue.
Identify adipocyte cells.
Differentiate between white adipose tissue and brown adipose tissue

HANDBOOK
Adipose tissue Adipocytes is a specialized type of connective tissue to store energy in the form of triglycerides, a molecule made of three fatty acids and glycerine. This tissue is composed mainly by adipocytes immersed in loose connective tissue, which can be found isolated or forming large aggregates called adipose panicles Adipose panicle . Occur in many areas of the body and represents 15% to 20% of body weight in normal weight men, while women represent between 20% and 25% of body weight.
Adipose tissue is the major repository of the body energy. Other energy storage organs, mainly the liver and muscle, which store glycogen, a faster molecule's energy metabolism than triglycerides, and have a caloric value of 4.1 kcal/g each caebohidrate, while triglycerides have a value of 9.3 kcal/g.
Because adipocytes are filled with triglycerides, have special physical properties, making the adipose tissue as a poor heat conductor, contributing to the thermal insulation of the body. For this reason, fat is found mostly in the subcutaneous layer of the skin, organized in the form of adipose tissue, especially in the slats of hands and feets. Due to the location of subcutaneous adipocytes, since they are present covering many organs like the kidneys, also reserve the function of protection against shock having the ability to absorb the force of impacts.
Finally, a function recently discovered thanks to the boom of the studies of adipose tissue in relation to the increase in world population obesity, are that adipocytes as well as being the body's energy reserves, have a strong relationship in the regulation of body metabolism of hormones and releasing a number of important factors, whereas adipose tissue could be the major body's endocrine organ.
There are two types of adipose tissue in different locations, structures and colors White and brown adipose tissue . White adipose tissue, the most common adipose tissue, consists in cells that are fully developed that contain a large central lipid droplet of yellowish, displacing the cytoplasm and the nucleus to the periphery. Brown adipose tissue consists of cells with multiple lipid droplets and numerous mitochondria, causing the brown color of this type of tissue. Both types of adipose tissues are highly irrigated.

WHITE ADIPOSE TISSUE OR UNILOCULAR ADIPOSE TISSUE Adipocytes
Adipocytes of white adipose tissue, that present a spherical morphology when are isolated and a polyhedral morphology when they are grouped Adipose panicle , are specialized in long time storage energy on a single lipid droplet unsurrounded by membrane. The cell cytoplasm is displaced to the periphery by the presence of the large central lipid droplet, like the nucleus, which adopts a flattened shape. Cellular organelles such as the endoplasmic reticulum, ribosomes and mitochondria, are preferentially located in the cytoplasmic portion surrounding the nucleus.
The color of white adipose tissue observed in a dissection depends on diet and varies from white to yellow, due to the presence of caroteniods dissolved in fat. In a microscopic observation, the adipocytes are observed as a spherical or polihedral cells with the cytoplasm moved to the periphery and flattened nucleus, but because during the processing of the sample has been sotmete to xylene baths and other organic solvents, that dissolve the lipid droplet, leaving a blank space instead Adipocytes . To observe the lipid droplet and the sample must be treated specially, avoiding organic solvents Stained adipocytes .
In a newborn, adipose tissue presents a more homogeneous distribution in the body. As the infant matures, fat tends to disappear from some parts of the body and increases in others. Its distribution is partly controlled by sex hormones, which control the deposition in the breasts and thighs.

BROWN ADIPOSE TISSUE OR MULTILOCULAR ADIPOSE TISSUE Brown adipose tissue
Brown adipose tissue, unlike white, has a more limited distribution in the body. Adipocytes of brown adipose tissue are filled with multilocular lipid droplets and has a brown color due to the large number of mitochondria scattered throughout the cytoplasm and the large amount of blood vessels supplying the tissue. The large number of mitochondria is due to the main function of this type of tissue, which is the production of heat, because the metabolism of lipids is decoupled from the production of energy, causing it to release as heat.
When animals that hibernate and mammals (including humans) are exposed to cold weather conditions, nerve impulses release noradrenaline in adipose tissue, promoting hydrolysis of triglicerides into fatty acids and glycerol in white adipose tissue, triglicerides in brown adipose tissue are metabolized rapidly increasing oxygen consumption, causing an increase of tissue temperature and heating the blood that passes though it.

EXERCICES
- Identify the adipose tissue (adipocytes) in the virtual slide. Adipocytes (fat cells) Masson's trichrome 7 um
- Differentiate the adipocytes from other structures of the virtual slide. Adipocytes (fat cells) Masson's trichrome 7 um