Regeneration Studies by Transplantation of Adrenal Tissue

The regeneration ability of the adrenal gland has been observed and recorded by several investigators; however, reports of the method of regeneration have been conflicting. This study was conducted to attempt to learn more of the method of adrenal gland regeneration through transplantation studies

Cell Mitosis During Skin Wound Healing

It has been well documented that an open (incised) skin wound through the epidermis and into the underlying dermis, results in a rapid, within 24 hours, and abnormal rise in the epidermal mitotic rate. The mitotic rate may be more than ten times the normal maximum, and is highest among those cells closest to the wound edge and lowest, near the normal rate, about 1 mm. from the wound edge. The decreasing mitotic rate within 1 mm. of the wound edge holds quite constant regardless of the size of the open wound. The theoretical explanation of this situation is presented by Bullough and Laurence (1 and 2) in the following three versions: 1. Following the theory that the epidermis is normally deprived of nutrients, it could be proposed that, since there is a marked hyperaemia around the edges of the wound, the increased mitotic activity may be due simply to a greatly increased supply of nutrients. 2. The high mitotic rate could theoretically be due to the stimulating influence of a wound hormone secreted from the wound itself. This has been the commonly accepted theory for nearly half of a century. However, the wound hormone theory was fully reviewed by Abercrombie (3), who concluded that in spite of many claims, no hormonal substance with mitogenic activity has been extracted from wound tissue, and the possibility must now be considered that no such substance exists. 3. The situation could be explained on the theory that the epidermis normally contains some substance which inhibits mitotic activity, and that the concentration of this substance is reduced in the immediate vicinity adjacent to the wound. This alternative is presently favored by most researchers in wound healing. The work of this author gives evidence that the zone of the highest mitotic rate in wounds caused by dry ice burns is not immediately adjacent to the wound periphery, as is the acknowledged in the instance of open (incised) wounds