The concentration of the plasma serotonin increased synchronizing with the stress load when it experimented on the VDT (Visual Display Terminals) work to a healthy person to know the influence of the mental stress on the mind and body. It aimed to confirm in research of this whether this cause was a result that the serotonin was released from the platelet. Because PDGF is stored to the platelet just like the serotonin, and it is released to blood when platelet is activated, the change of plasma PDGF concentration when the VDT work stress was loaded was measured. As a result, plasma PDGF concentration increased significantly after the load of the stress compared with before the load though the concentration of serum PDGF did not show a significant change. These results suggested that the cause to which the serotonin is increased in blood is partially release from platelet. The platelet might be activated partly at the acute mental stress.

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The purpose of this study was to investigate the effects of changes in daily light-dark cycles on physical parameters, hormone secretion and embryo growth in pregnant rats.
Forty-three 8 weeks old female Wistar rats were randomly divided into four groups; non-pregnant control group (n=10), pregnant control group (n=10), non-pregnant shift group (n=12), and pregnant shift group (n=11) . The control group bred in daily common light-dark cycle (light period 9: 00-21: 00, dark period 21: 00-9: 00) . The shift group bred in shifting of daily reversed light-dark cycle (light period 21: 00-9: 00, dark period 9: 00-21: 00) and common cycle. The common cycle was set in the first day (day 0), and the reversed cycle was set in the second day (day 1) . And then the common cycle was set in the third day (day 2), and similarly, shifting of the cycles was repeated in the following days.
The blood sugar in the pregnant shift group was higher than in the other groups. On the contrary, the body weight of embryo in the shift group was less than that of the control group. Furthermore, although corticosterone concentration showed no difference between shift and control groups, noradrenaline concentration of the shift group tended to be higher than those of the control group.
We conclude that growth retardation of embryos may result from increased noradrenaline secretion. It is strongly suggested that the reversed light-dark cycle acts as the stressor especially for pregnant mothers.

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The epithelium and the lamina propria of the human anal canal were investigated by light microscopy, scanning and transmission electron microscopy.
Based on histological findings, we defined the anal canal as follows. It was a canal situated between the the anorectal junction and anal margin, ranging from 3.5 cm to 4.0cm. The anal canal was divided into the supradentate part and the infradentate part. The anus and the infradentate part consisted of the keratinized stratified squamous epithelium, and keratinization of the epithelium apperared to be a less degree in the infradentate part. The supradentate part consisted of the non-keratinized stratified squamous epithelium. In contrast with the anal canal, the rectum consisted of the simple columnar epithelium. It was concluded that the anal canal was strongly from mechanical stimulation but there was considerable risk of damaging in the rectum.

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In order to understand the correlation between the impulse and activation sequence, the cytoarchitecture and innervation of the sinoatrial (SA) node in the rabbit heart were investigated by scanning (SEM) and transmission electron microscopy. For SEM, tissue specimens including the SA node were treatred with 6N NaOH to remove both the endocardium and connective tissue.
The SA node consisted of small bundles of nodal cells. The nodal cells were smaller in size than atrial myocytes, spindle-shaped, and had a moderate number of myofibrils, small mitochanclria and many glycogen particles. They were contacted end-to-end or end-to-side with each other at the intercalated disks.
The nodal cell bundles were mostly oriented pararell to the crista terminalis, but some cell bundles with a reticular net were found. At the periphery of the SA node, nodal cells were combined with atrial myocytes. In addition, adrenergic and cholinergic nerve endings were in close proximity to the nodal cells.

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