Upper Lid Thick Skin Blepharoplasty

While many of the basic tenants of upper lid blepharoplasty remain constant regardless of skin type, the thick-skinned eyelid patient requires special consideration. The brow may be naturally lower in the thick-skinned patient. These patients are more prone to having the brow pulled downward while attempting to remove redundant skin. There may also be more fat in the medial and central compartments. There may be fat in a lateral compartment overlying the lacrimal gland. Patient's expectations for a deep lid sulcus and complete excision of redundant skin may not be possible. They are more prone to an observable scar, a small dog ear at the lateral wound edge, and prolonged postoperative lid edema. Patients with lifelong upper lid fullness must get some input from significant others because their upper face aesthetic will change. In these patients, the eyelid surgery is not a rejuvenation, but a creation.

Wound effects in the xylem of poplar: A UV microspectrophotometric study

Cell wall modifications in vessels and fibres of wound wood of Populus tremula L.×P. tremuloides Michx. formed after mechanical wounding have been examined by light microscopy, transmission electron microscopy, and UV microspectrophotometry (in scanning and point measurement mode), mainly focusing on the lignin distribution. With this goal, wound xylem within lateral wound callusis was collected after response periods of up to 23 months. Vessels and fibres in wound xylem deviated from their usual axial orientation. Vessels within the wound xylem were smaller in diameter and shorter in length. Xylem fibres were also shorter and developed thicker walls, especially in tissue adjacent to the wound. Cell walls and cell corners of these fibres showed on average a higher lignin content and a modified lignin composition. These wall changes probably enhance disease resistance of the wound tissue. With increasing distance from the wound edge, the modifications diminished and finally disappeared.

The integration of plant behaviour V—Growth substance and traumatic curvature of the root

The manner of response of the root to injury is well known. A lateral wound made within 1 mm or 2 mm of the extreme tip gives rise to a negative curvature: the root curves away from the wound. A similar injury made elsewhere in the growing region evokes a positive curvature; the root curves towards the wound. The curvatures are manifestly growth curvatures. Like those induced by gravity, traumatic curvatures are the consequence of unequal growth of opposite sides of the region of elongation. In the one case they are undoubtedly brought about by the stimulus of gravity; and in the other they are supposed also to owe their origin to a stimulus, a wound stimulus. But, whereas something at all events is known of the way in which the stimulus of gravity acts on the root, the mode of operation of the wound stimulus—if stimulus there be— remains obscure. The Went-Cholodny hypothesis of geotropism which is supported by Cholodny’s experiments (1924, 1926), those of the authors in collaboration with R. Snow (1931), of Boysen-Jensen (1933, a, b ), and others (Snow, 1932), attributes to growth substance contained in the root an essential part in geotropic curvature. It holds that growth substance which inhibits the growth of the root is a normal secretion of the root tip. Produced continuously by the tip, it passes upwards by straight paths and reaches all parts of the region of elongation. Although in the passage through the elongating region the concentration falls off progressively, the dis­tribution of growth substance at any given level is uniform and therefore, the inhibitory effect being equal on all sides, the unstimulated root continues to follow a straight downward path. When, however, the root is exposed to the stimulus of gravity the uniformity of distribution of growth substance is disturbed; more is found to occur on the lower than on the upper side of the tip and the inequality of distribution is held to be due to a passage downward from the one side to the other. Since the lower side of the tip now contains more, and since growth substance travels from tip to elongating region by straight paths, the lower side of the elongating region comes also to contain more than the upper side; the upper side grows faster than the lower and the root curves downward.