TCMC - Histology: Adipose Tissue

Brown fat is found within what two (2) regions of humans?

1. Interscapular 2. Inguinal **The amount of brown fat in these areas decrease after birth

Two (2) major types of adipose tissue

1. White adipose tissue 2. Brown adipose tissue

In adults, brown adipose tissue is found only in scattered areas, especially around the: 1. 2. 3. 4.

1. kidneys 2. adrenal glands 3. aorta 4. mediastinum

What two (2) characteristics constitutes white adipose cells in having a "signet ring" conformation?

1. the nucleus is at the periphery of the cell 2. the cytoplasm is a thin peripheral layer within the cell

Function(s) of adipose tissue

1. thermal insulation 2. storage depots 3. metabolic regulation 4. hormone release 5. cushioning

Brown adipose tissue constitutes ___ to ___% of the newborn body weight, but it is greatly reduced during childbirth and adolescence.

2-5%

When completely developed, a white adipocyte is between ______ and _______ micrometers in diameter.

50 and 150 micrometers

Adipocytes of white adipose tissue are _________ when isolated, but are ______________ when closely packed in situ.

Adipocytes of white adipose tissue are spherical when isolated, but are polyhedral when closely packed in situ.

Adipose tissue normally represents _____ to _______% of the body weight in men.

Adipose tissue normally represents 15 to 20% of the body weight in men.

Because brown adipose cells have many mitochondria, it can generate ________ and its _________ _________ is more intense.

Because brown adipose cells have many mitochondria, it can generate heat and its metabolic activity is more intense.

Why are brown adipose tissues darker in appearance?

Cells of brown adipose tissue is abundant in mitochondria (that contains cytochrome pigment) located in the lipid droplet

T/F: Cells of brown adipose tissue receive direct parasympathetic innervation, which regulates their metabolic activity.

False: Cells of brown adipose tissue receive direct SYMPATHETIC innervation, which regulates their metabolic activity.

T/F: Regions containing loose connective tissue septa of brown adipose tissue, do not contain blood vessels.

False: Some of the septa have blood vessels associated with them

T/F: Tissue rich in fat conducts heat well, and provides thermal insulation for the body.

False: Tissue rich in fat conducts heat POORLY, and provides thermal insulation for the body.

Why do hibernating animals have more brown adipose tissue?

Hibernating animals need a constant energy source. They need to generate heat internally, and brown adipocytes, with its many mitochondria, can undergo autonomic stimulation in cold weather to release energy as heat. The high number of blood capillaries in brown adipose tissue is responsible for carrying the heat to the entire body.

Why are adipocytes of white adipose tissue uniocular in nature?

In white fat cells (adipocytes), individual lipid droplets fuse to form one large droplet that eventually ends up occupying the entire cell.

What is said to divide brown adipose tissue into "lobes"?

Loose connective tissue septa

What stain could one use in order to visually preserve the lipid droplet(s) contained within adipocytes?

Osmium Tetroxide! Osmium preserves the lipid and stains it black.

Cells of brown adipose tissue are _________ in shape.

Polygonal

What happenes to the thin rim of cytoplasm that remains after an adipocyte undergoes dissolution of its lipid core?

The cytoplasm may shrink, collapse, or rupture, ultimately distorting the cell and tissue structure.

The cytoplasm of fat cells (adipocytes) contain large _____________ deposits in the form of one or more _________ droplets with no limiting membranes.

The cytoplasm of fat cells (adipocytes) contain large triglyceride deposits in the form of one or more lipid droplets with no limiting membranes.

Why are the nuclei of brown adipocytes more centrally located in the tissue?

They have smaller lipid droplets

Why are unilocular adipocytes often appear empty in standard light microscopy?

They typically appear empty because lipid is removed from cells by xylene or other solvents used in histological techniques.

T/F : Adipocyte clusters throughout the body constitute an important metabolic organ that varies in size and distribution, depending on age, sex, and nutritional status.

True

T/F: Adipose tissue is highly vascularized.

True

T/F: The multiple small fat droplets that appear during development of brown adipocytes do not coalesce during development.

True

Unlike other cells of connective tissue proper, adipocytes are individually surrounded by a thing external lamina containing _____________________.

Type 4 collagen

White adipose is to _____________, as brown adipose is to _____________.

White adipose is to unilocular, as brown adipose is to multilocular.

This type of adipose tissue is the most abundant in terms of fat storage

White adipose tissue

Adipose tissue differs from other forms of connective tissue, in that individual adipose cells are surrounded by a thin ______________, that may or may not be visible in light microscopy.

basal lamina

Brown adipocytes are often closely packed around large ___________.

capillaries

Multilocular

cell contains multiple lipid droplets

Unilocular

cell contains one (1) lipid droplet

Adipose cells have a ________ appearance as a result of the dissolution of the lipid droplet during processing, thus leaving an empty space in the cell.

clear

The multiocular adipocytes of brown adipose tissue derive from from ___________ precursors that assume an epithelial shape and arrangement.

mesenchymal

Adipose

specialized connective tissue in which fat--storing cells/adipocytes predominate