SLIDES 106,109 AND 110 - Tongue.   The tongue is a muscular structure that can be voluntarily moved in many directions, so you will not be surprised to see that much of its substance consists of bundles of skeletal muscle interlaced in many different planes.  Interspersed with the muscle, you may see adipose tissue, blood vessels, nerves, loose connective tissue, and mucous or serous glands with their ducts.  (The nuclei of serous secretory cells are rounded; the nuclei of mucous cells are flattened at the base of the cells.)  Look to see how many of these elements are present in each of your slides of tongue.  We will study these in more detail next semester when we do salivary glands.

If a section has been taken through the entire thickness of the tongue (see #106) you will find a smooth, relatively thin stratified squamous epithelium covering the under surface, and a  rougher, somewhat thicker stratified squamous epithelium covering the  upper  surface.  There are many small projections, or papillae, on the upper surface, each with its core of loose connective tissue.  Papillae may be thin and pointed (filiform), leaf-like (foliate), fairly broad and stubby (fungiform) or very large and surrounded by a moat-like furrow (circumvallate).  What kinds of papillae do you see in each of your three sections?  Both the foliate (slide 110) and the circumvallate (slide 109) types have numerous taste buds on their lateral walls.  How are taste buds structurally adapted to the reception of stimuli?