The chief purpose of this paper is to study the mucin production in the intestinal epithelial cells and the development of the goblet cells. The author has investigated cytologically the mucous menbrane of the duodenum. Materials were taken from 5 healthy executed men. For the demonstration of mucin the FEULGEN-BAUER reaction, the periodic acid SCHIFF reaction (PAS reaction) and the MALLORY stain were employed.
The GOLGI apparatus of the goblet cell consists of branched threads which occupy the cytoplasm between the goblet and the nucleus and embrace the bottom of the goblet extending upward into the thin cytoplasmic layer of the side wall of it.
The great majority of the mitochondria of the goblet cell is of filamentous or rod-like shape and most of them accumlates in the cytoplasm between the goblet and the nucleus, they spread also into the cytoplasmic layer of the side wall of the goblet. A small amount of them is found in the cell basis.
From the morphological changes of the GOLGI apparatus and the mitochondria it is concluded that the chief cells (columnar cells with striated border) may turn into goblet cells.
There is a characteristic difference between the goblet cells and other ordinary mucous gland cells, in that both GOLGI apparatus and the mitochondria do not exist in the goblet.
Mucin granules arise in intimate contact with the GOLGI apparatus, namely they are formed within the threads or in the meshes of the GOLGI net. There is no evidence which show definitely that the mucin granules arise from the mitochondria.
The epithelial cells of the small intestine increase by mitosis in the crypts of LIEBERKÜHN, then they move upward to the villi and substitute the desquamated cells. Consequently the epithelial cells of the crypts are younger than that of the villi. By the PAS reaction it can be demonstrated that all epithelial cells with striated border (chief cells) of the crypts have the ability to produce mucin; all of them always contain small mucin granules in various numbers in their apical portion. In this way some of these cells turn into goblet cells and reach the epithelium of the villi in this ferm, while the others lose this ability and move as the chief cells to the villi.
The chief cells on the villi have therefore in normal conditions no mucin granules, they keep, however, the ability to produce the mucin in a latent state and under certain conditions are mobilized to epithelial cells producing mucin and turning into the goblet cells.