Page 196 - My FlipBook

206 ANATOMY.

granules are found only in the part of the cells which is close to the
lumen, and in those parts which are contiguous to the adjacent cells
(corresponding, perhaps, to fine capillary clefts which pass from the
cavity of the alveolus between the cells). The nuclei have now become
Fig. 101.

Alveoli of a Serous Gland : A, at rest ; B, after a short period of activity ; C, after a prolon;,'ed period
of activity. In A and B the nuclei are obscured by the granules of zymogen.
distinct and the cells are smaller ; we may suppose, therefore, that the
granules, which no doubt contain the specific elements of secretion, are
formed by or from the protoplasm of the cells during rest, and are dis-
charged into the lumen and dissolved during activity. Probably, how-
ever, during activity, new granules are constantly being formed and
passed outward toward the lumen. According to Langley, the three
processes—of growth of the clear protoplasm, conversion of this into
granules, and discharge of these into the lumen—are all proceeding
^
simultaneously in different parts of the cell during activity."
TJie Muco-saUvary Glands.—Examples: the submaxillary glands of
man and of the guinea-pig. They are all compound glands with a
double function, which makes their anatomy complicated. Some of
the lobules composing the gland are constructed and their functions
are the same as tho.se of the pure mucous glands (sublingual gland of
man), while other lobules are constructed and their functions are the
same as the pure salivary glands (the parotid of man) ; even some of
the convoluted tubes in the same lobule differ, some having the func-
tion of secreting mucus, while others secrete saliva.
" Besides these three forms, Bermann has observed that in connection
with a large gland of Wharton's duct in many mammals he has discov-
^
ered a compound tubular mucous gland of unique structure."
The special mucous and salivary glands associated with the mouth,
nose, ancl pharynx are labial, buccal, molar, palatine, lingual, parotid,
submaxillary, sublingual, and lachrymal.
The Labial Glands are of two kinds—the mucous and sebaceous.
The mucous glands are small round racemose or compound tubular
glands about the size of small peas, situated between the mucous mem-
brane and the orbicularis oris muscle ; their ducts open upon the mucous
membrane. The sebaceous glands are small, and situated on the outer
part of the red margin of the lip.
The Buccal Glands are smidl i^ound racemose or compound tubular
glands (smaller than the labial), situated between the mucous membrane
and buccinator muscle ; the ducts open upon the mucous membrane.
The 3Iolar Glands are small round racemose or compound tubular
^ Quaiii's Anatomy, 9th ctl. ^ Coles's i\ncroscnpical Science.