No abstract

Examinations of stages of fibril development in muscle fibers of seven Rhesus monkey and six human fetuses reveal SR tubules encircling the Z lines at all stages of fibril development. The encircling SR tubules are continuous with the SR network of tubules which is found surrounding fibrils at all stages of development observed. The SR tubules encircling the Z lines show connections (electron-opaque strands) with the Z lines. The developing triadic junction shows a progressive increase in complexity of structures within the junction. First, membranes of T and SR become apposed with no visible structure between them- Second, tenuous connections are found traversing the space between apposed membranes. Third, well developed bridges are seen traversing the space. And finally, an intermediate density midway between the apposed membranes and parallel to them is found in favorable sections. Junctions between T tubule membranes were also observed and the structures in these junctions are somewhat similar to those found in junctions between T and SR membranes. The change in orientation of triads from predominantly longitudinal to predominantly transverse is complete in the 18-week monkey fetus and incomplete in the latest stage (28-week) of fetal development observed in humans.

Interest has recently been focused on the relationship which seems to exist between slow potential changes appearing in the electroencephalogram (EEG) on hyperveiltilation and alterations in blood sugar level.'* If a direct relationship between the two does exist, it will be necessary systematically to control the blood sugar level in all hyperventilation studies. it is not easy to maintain such a control, and before the electroencephalographer becomes burdened with this precaution, it seemed desirable to investigate the possible relationship further.Methods. One physically healthy, schizophrenic patient was observed on 10 different occasions* over a period of 10 weeks.Three glucose and 7 insulin (3. 5, 10 U ) tolerance tests were given.Preceding the collection of each blood sample an EEG was obtained in the following iiianner: j meters of control record were followed by a 2-minute hyperventilation (at a regular rate of 30 deep respirations per minute), and the record allowed to return to its initial level. In this n a -, inany hyperventilation records at various blood sugar levels were obtained.Slow activity in the EEG was considered to include all waves with a frequency below 8 per second, and was qualified as total slow activity in the 7-meter period, which included the hyperventilation and recovery portions of the record. Fig. 1 A shows a definite inverse relationship between bIood sugar and sIow activity. Fig. 1 B, however, is typical of the remainder of our data. Here slow activity is inversely related to blood sugar only at 30 and at 90 minutes. In addition, it may be noted that the minimum amount of slow activity does not correspond with the maximum blood sugar value.When all the blood sugar values obtained were plotted against the corresponding amounts of slow activity, an apparent relation-Resalts.