Hidekatsu Matsumura

Freeze-Fracture Replica Studies of Tight Junctions in Normal Human Bronchial Epithelium

Using freeze-fracture techniques, tight junctional networks were observed in the human normal bronchial epithelium. They were morphologically classified into three types: type I was a loosely interconnected, most complicated network consisting of 7-11 roughly parallel wavy strands and situated between ciliated cells; type II was a randomly anastomosing, simple network made up of 2-4 strands and present between goblet cells; type III was an irregularly anastomosing network composed of 4-7 strands and located between a ciliated cell and a goblet cell. Type III junctions, when a goblet cell was strongly bulged, were located on the swollen ridge, the upper surface of which was separated by a deep groove from the bulged apical surface, around the lateral surface of the cell at the level of the luminal surface. The possible relation between the orientation of strands of these networks and extra- or intracellular stress was discussed.

Effects of Pilocarpine Treatment and of Electrical Stimulation of the Vagus Nerve on the Rat Parathyroid Gland, with Special Reference to the Alteration of Storage Granules

Effects of pilocarpine treatment and of electrical vagal stimulation on the rat parathyroid were studied ultrastructurally. The number of type I storage granules with a narrow halo (NSG-I) and that of type II storage granules having a wide halo (NSG-II) were calculated. After pilocarpine treatment, NSG-I gradually decreased and reached a minimum at 30 min; in contrast, NSG-II gradually increased and reached a maximum at 20 min, but thereafter it slightly decreased and instead vacuolar bodies increased. Excluding these alterations, the ultrastructure of parenchymal cells showed no remarkable changes. Electrical vagal stimulation furthermore confirmed these results. Acid phosphatase activity was occasionally found in storage granules of both types in control and experimental rats. It was concluded that storage granules normally may be transformed from type I into type II and finally into vacuolar bodies as a result of hydrolysis, and that these processes may be accelerated by parasympathetic stimulation.

Effects of Epinephrine Treatment on the Rat Parathyroid Gland, with Special Reference to the Frequency of Storage Granules

Effects of epinephrine treatment on the rat parathyroid gland were studied morphologically. The mean number of storage granules per cell section (NSG) was rapidly decreased as early as 5 min after an injection of epinephrine and seemed to reach a minimum between 5 and 30 min. During this period, serum calcium levels (SCL) gradually rose and reached a maximum at 30 min. The ultrastructure of chief cells in these epinephrine-injected rats showed no marked difference as compared with that in control rats. In slightly hypocalcemic rats, induced previously by 2% EDTA-treatment, NSG was more rapidly decreased. It was suggested that storage granules may be released promptly by epinephrine treatments in spite of high SCL and that they are more promptly released under hypocalcemia.

ENDOTHELIAL TUBULORETICULAR STRUCTURES IN INTRACRANIAL GERMINOMAS

In studying three human intracranial germinomas tubuloreticular structures were observed within the cisterns of granular endoplasmic reticulum (RER), as well as occasionally within dilated perinuclear spaces of capillary endothelial cells. These tubuloreticular structures seen as a network of branching, convoluted, tubular profiles appear to originate from amorphous material. The development of these structures could be classified into three stages. In Stage I, the precursor substance appears as dense amorphous material within the cisterns of RER. Stage II is marked by the transformation of the amorphous material to coarse particulate material which aggregates to form tubular units. During the first and second stages, the distended RER that participates in the formation of these structures is accompanied by numerous attached ribosomes and is closely associated with mitochondria. In Stage III, the tubular units fuse with one another to form the tubuloreticular structure. In this third stage both ribosomes and mitochondria are almost absent. As a result of the almost complete disappearance of these organelles at this time, both the attached ribosomes and mitochondria may play an important role in the synthesis of the precursor substance as well as in its transformation to the tubuloreticular structure.