WAT Murine
Thin parts of adipose organ, fresh or fixed, can be observed at light microscopy before further processing (embedding). In this plate two examples are shown. In the upper plate the external area of a fat lobule from the epididymal fat of a young mouse is
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WAT Murine
© Springer International Publishing Switzerland 2018 S. Cinti, Obesity, Type 2 Diabetes and the Adipose Organ, https://doi.org/10.1007/978-3-319-40522-3_4
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WAT Murine
4.1 PLATE 4.1
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WAT Murine
Thin parts of adipose organ, fresh or fixed, can be observed at light microscopy before further processing (embedding). In this plate two examples are shown. In the upper plate the external area of a fat lobule from the epididymal fat of a young mouse is shown. Note the extremely regular size of the cells without any artifact due to the embedding procedure. The size of adipocytes in fresh samples is about 20–30% larger than that measured in sections of tissue routinely processed for light microscopy. In the bottom panel a lobule of omental fat sampled from a young mouse is shown. Interestingly the vasculature tree is well visible and marked in red by the red blood cells. Peripheral branches of vessels are smaller and tightly connected to small adipocytes in line with the well-known correlative relationships between these structures during adipogenesis.
Pre-embedded WAT
60 µm
200 µm
Plate 4.1 Fresh unstained epididymal (upper) and omental (lower) WAT from young mice. LM 109
WAT Murine
PLATE 4.2
The white areas of the adipose organ are constituted of white adipose tissue (WAT). The histology of this tissue is similar in several species (compare with plates in Chap. 5) and shown in the upper panel. White adipocytes are spherical because this shape allows the maximum volume in the minimum space. This is therefore the ideal shape for a cell storing the most important source of energy for the organism. A single lipid droplet surrounded by a thin rim of cytoplasm occupies most of the cell volume. The nucleus is pushed to the periphery. At the light microscopy level, capillaries can be seen running among adipocytes. The size of white adipocytes varies with species, type of depot, nutritional state, and environmental conditions. The adipocytes of subcutaneous depots in B6 mice maintained in standard conditions, chow diet and 22–24 °C (peripheral inguinal area, about 2000–3000 microns square), are usually larger than those of visceral depots (mesenteric, 1000–2300 microns square). Of note, the size of white adipocytes is usually very different also in a specific depot; thus, for example, the size in inguinal subcutaneous depot is smaller in the peri-lymph node area than in the peripheral area. In visceral depots it is smaller in mesenteric than in epididymal depot, and in epididymal fat, it is smaller in the central part (near the epididymis about 2000–2500 microns square) than at the periphery (far from the epididymis about 3000–3500 microns square). Since many years white adipose tissue can be divided into two fractions with a well-established and simple method based on collagenase separation of the cells and centrifugation. Because of the lipid content in mature adipocytes, these cells are located in the floating fraction after collagenase and centrifugation steps. The rest of the tissue forms the
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