LARYNX. 85 
may be formed. The contents of such a cyst are made up of the 
detritus of the decomposed tissue. 
(5) Cysts whose wall is formed by inflammatory exudation around 
foreign bodies, parasites, extravasated blood, etc. 
(ce) Cysts formed by a new growth of tissue, in the spaces of which 
various kinds of fluid accumulate. The spaces may or may not be 
lined with epithelium. Some of the compound ovarian cysts are 
examples of this type. 
(d) Congenital cysts, their mode of origin is not well understood. 
Dermoid cysts of the subcutaneous tissue and of the ovary are of this 
class. They contain a greasy material mixed with elements of the 
skin, hair, teeth, nails, ete. 
RESPIRATORY SYSTEM. 
LARYNX. 
What are the changes in an acute catarrhal laryngitis ? 
The microscopical changes are not marked. There is an increased 
desquamation of the superficial cells and an increased production of 
the deeper cells. A few pus cells are also found. The mucous mem- 
brane is at first congested, swollen and dry. Soon the mucous glands, 
becoming more active, produce an increased amount of mucus. 
How is the larynx affected in chronic catarrhal laryngitis ? 
The mucous surface is coated with muco-pus; the stroma is infil- 
trated with cells and is thickened or thinned, or it may be necrotic or 
ulcerated. The mucous glands are swollen and prominent. 
What is croupous laryngitis ? 
It is an exudative inflammation in which the mucous membrane is 
covered with fibrin and pus. These elements infiltrate the stroma, 
and cause coagulation necrosis of the epithelial cells. 
What are the changes in syphilitic and in tubercular laryngitis ? 
The surface of the mucous membrane may be covered with muco- 
pus. Small ulcers are often seen. The products of inflammation are 
the same as those described under syphilitic and tubercular inflam- 
mation. 
What change takes place in edema of the glottis ? 
The tissues are infiltrated with a serous exudation, and become 
enormously swollen. 
