Adipose tissue is an multifunctional organ which is associated with many physiological functions. It plays a protective role, stores fat and is the biggest endocrine organ. These tissue is physiologically and morphologically differentiated. Adipocytes which built adipose tissue might be divided into two main groups: white (which build white adipose tissue-WAT) and brown (which build brown adipose tissue-BAT). Their morphology is differentiated due to genetic, metabolic and environmental reasons [1,2,3].
The main role of white adipose tissue is storage of triglycerides during increased energy supply and using them during periods with increased energy expenditure. The percentage of this tissue is highly variable: from 3% in athletes to even 70% in obese people . In humans these tissue is produced during fetal life (14-24 weeks of pregnancy) [5,6], whereas in rats and mice it is produced postnatally [7,8].
The morphological and functional changes in WAT occurs with obesity. The surplus energy stored in the form of triacylglycerols during chronic positive energy imbalance results in changed of adipocytes size (hypertrophy) and in number (hyperplasia) . Adipose hypertrophy results from a comparative increase in lipid deposition against to lipolysis [10,11]. The hyperplasia of adipocytes results as effect of adipogenesis. It is process of preadipocytes (adipocyte precursors) compensation by dividing and differentitation into adipocytes. It occurs when demand for lipid storage transcends the existent adipocytes [12,13,14,15].
WAT increasing is associated with obesity, Cushing’s syndrome, hypogonadism. Waste of adipose tissue occurs in many pathological situations, like cachexia, certain parasitic infection and HIV infection [16,17,18,19,20]. Measuring the size and number of adipocytes in deposition, development and remodeling of WAT is relevant in phenotype characterization of a given adipose tissue depot.
Actually there is a few popular methods to quantitative histomorphometry of these tissue. Most of them require the enzymatic disruption of tissue to isolate the individual population of adipocytes, which might be stained and analyzed by coulter counter or flow cytometry [21,22,23]. The main disadvantage of these methods is destruction or elimination of some part of adipocytes after enzymatic digestion, centrifugion or mesh separation. The main drawback of flow cytometry is separation of adipocytes by size as a result of analysis of internal lipid accumulation .
In other technologies scientists might use different lipophilic fluorophores which bound to the lipids in adipocytes. Confocal analysis of this results is expensive and tedious (1000 adipocytes is needed for accuracy) .
Another substances which are useful to adipocyte staining might be toxic and promote adipocyte swelling (e.g. osmium tetroxide which is used in microcomputed tomography to visualize narrow adipocytes) [22,26].
The most popular staining of adipocytes is hematoxylin and eosin solution. Dicella proposed semiautomated software to analyze adipocytes size and number. These software is easy to use and rapid.
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