On the welcome page of the dictionary, three major sections are shown: Normal tissues, Cancer and Cell structure. Below the image of each section are links to introductory texts for i) normal tissue histology, ii) hallmarks of cancer, and iii) cell structure overview. For the cancer-section there is also a link to current cancer statistics (incidence, survival, etc) for Sweden and the rest of the world. Within each section there are direct links to histology descriptions of different tissue types and tumor forms as well as descriptions of cell structures.
For the 'Tissue & cell types' and 'Tumor' sections, tissue-slides stained with hematoxylin and eosin (HE) are shown at three different levels of magnification. On the top level, an overview of the whole tissue-sample is shown with boxes in black indicating where zoomed-in representative parts of the tissue are available for viewing. Clicking on these boxes will zoom in on that part to show tissue structures, cells and features in greater detail. Throughout these sections, arrows indicate relevant tissue structures, cell-types and other features.
For the 'Cell structure' section, immunofluorescent images of formaldehyde-fixed cell lines are shown. The various cell structures that are demonstrated are always shown in the green channel using an antibody found in the Human Protein Atlas. The antibody name is linked to the subcellular location summary page of the target gene. The other channels: nucleus, microtubules and endoplasmic reticulum, are always shown in the blue, red and yellow channels, respectively. The channels can be toggled on and off by clicking on the respective coloured button above the image. When applicable, the immunofluorescent images are complemented by immunohistochemically stained cells where the location of the particular cell structure is shown in brown.
A common feature for all sections is that a general descriptive text about the tissue, tumor-type or cell structure is provided when browsing a particular topic.
The major salivary glands are the paired parotid, sublingual and submandibular glands. They produce saliva, a mixture of serous and mucinous secretions that chiefly contains water, proteins, glycoproteins and electrolytes, that is secreted into the oral cavity. Saliva is rich in enzymes that initiate the breakdown of the food we eat and lubricates ingested food to facilitate swallowing.
Connective tissue capsules surround the salivary glands. Septa from the capsule divide the gland into lobes and lobules and also carry larger arteries and veins. The salivary glands are compound tubuloacinar glands, which means they have branched ducts ending in sac like dilations (acini) where the excretory cells are located. The secretory unit of the salivary gland is the salvion, consisting of an acinus, intercalated duct, striated duct and excretory duct.
The acini can be of serous, mucous or mixed type. The serousacini secrete a fluid that is rich in proteins. The cells of the acini are triangular in shape and appear darkly stained with HE. The basal portion of the glands appear darker stained due of the presence of rough endoplasmic reticulum and the round basally located nuclei in the cells. The apical portion stains lighter due the presence of secretory granules. Mucousacini can easily be distinguished from serous acini, as the cells of the mucous acini are paler and contain flattened nuclei located towards the base of these cells.
Intercalated ducts, with low cuboidal epithelium, lead away from the acini. In serous secreting glands these small ducts are more evident and secrete bicarbonate and absorb chloride ion from the acinar secretions.
Striatedducts connect the intercalated ducts with the larger excretory ducts. They are lined with simple cuboidal or simple columnar epithelium, depending on the size of the duct. They are termed striated ducts because the basal plasma membrane folds into the lower portion of the cell, resulting in a striated appearence. The nuclei are spherical and located to the middle of the cell.
Excretory ducts are located in the interlobular and interlobar connective tissue. As the diameter of the ducts increase, the epithelium changes from simple cuboidal to pseudo stratified columnar or stratified cuboidal. Excretory ducts eventually open into the oral cavity.
Within the salivary glands there are also aggregations of adipocytes. Fat is stored in adipocytes as a single large lipid droplet. In routine embedding of histological specimens the lipid is dissolved, leaving a large unstained and empty appearing space within each adipocyte. The nucleus is flattened and displaced by the lipid droplet to the periphery of the cell.
