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Biomedical subjects

W Montagna

Publications and source records attributed to W Montagna.

9 recordsLinked to original sources
PubMed1979

Structural changes in aging human skin.

In both exposed and protected areas of progressively older people the underside of the epidermis becomes increasingly flattened out. This flattening is accompanied by a comparable rarefaction of the superficial blood vessels. In this article we review the architecture of the elastic fiber framework in the papillary dermis of skin protected from the sun; aging changes that occur are similar to, but less severe than, those in sun-exposed areas. Most cutaneous sensory end organs are little affected by aging; those in the external genitalia, however, and particularly those underneath the vaginal epithelium become smaller and some disappear.

Adolescent↗
PubMed1979

Aging model for unexposed human dermis.

Young human dermis is charterized by the presence of many fibroblasts with distended endoplasmic reticulum, extensive Golgi bodies, and orderly and "clean"-appearing groundwork. Older dermis contains inactive fibrocytes with lipofuscin-like granules, macrophages with dense granules, and extracellular spaces with evidence of degeneration. We have found the sex skin of cycling pigtail macaques (Macaca nemestrina) a predictable model for studies on aging changes in human dermis. Swollen sex skin has many biochemical and ultrastructural properties that are similar to those of young dermis, and deflated sex skin resembles older human skin. Sex skin, however, is unique in that it becomes "rejuvenated" with each succeeding ovarian cycle. This animal model may prove useful to researchers attempting to increase their understanding of aging in connective tissue.

Aged↗
PubMed1976

Catecholamine-containing nerve terminals in piloarrector muscles of stump-tailed macaques (Macaca arctoides) and the effects of local injection of 6-, and 5-hydroxydopamine.

The fluorescence histochemical method of Falck-Hillarp (62) demonstrates dense plexuses of catecholamine-containing nerves in the piloarrector muscles of adult stump-tailed macaques. When these muscle fibers are viewed under the electron microscope, most of the axon terminal profiles between them contain numerous dense-cored vesicles (adrenergic); the rest of the terminals contain mainly agranular vesicles (cholinergic). Intradermal injections of 6-hydroxydopamine (6-OHDA, 1 and 5 mg) or 5-hydroxydopamine (5-OHDA, 10mg) into the scalp caused the fluorescence from the nerve fibers in the muscles to completely disappear. The 6-OHDA injections induced severe degenerative changes in the adrenergic terminals whereas the 5-OHDA injections caused only the granules in the vesicles to increase in numbers. Thus, the piloarrector muscles of these macaques are innervated with both adrenergic and cholinergic terminals, but the former are more numerous than the latter.

Animals↗
PubMed1976

The skin of the giraffe.

The skin of the giraffe has the same general histological structure as that of other mammals, but there are notable features. The skin is heavily pigmented with the epidermis, pilary canals, and the outer cell layer of the apocrine duct richly melanized. Furthermore, melanotic dendritic cells are frequently found in the sebaceous glands, the entire length of the external root sheath, and the secretory tubules of the apocrine glands. The thick skin has a papillary dermis that extends to just beneath the secretory coils of the apocrine glands and bulbs of hair follicles and an equally thick reticular layer below these structures. The hair follicles do not grow in clusters, and with some regional variations, have associated sebaceous glands, apocrine glands, and arrectores pilorum muscles. Only the large hairs have a prominent medulla. In such specialized regions as the eyelids, nose, and lips, the apocrine glands are surrounded by cholinesterase-reactive nerves but the glands on the general body surface are not. The only specialized nerve receptors are hair follicle end organs found on every hair of the eyelids, nose, and lips, but only rarely elsewhere.

Animals↗
PubMed1976

Histology and cytochemistry of human skin. XXXVI. The nose and lips.

The skin of the nose is characterized by often conspicuously dilated openings of the ducts of many subaceous follicles. Histological sections are dominated by gigantic sebaceous follicles, but there are also numerous vellus hairs with small sebaceous glands. All hair follicles on the surface of the nose and in the vestibule are completely invested with nerve end organs. In the vestibule, the glabrous upper surface has intraepidermal nerves and a few mucocutaneous end organs. the vermillion zone of the lip, which seperates the skin of the external lip and the mucosa of the inner lip, is keratinizing glabrous epithelium, often with numerous sebaceous glands in the upperlip. The transitional area between the keratinizing epithelium of the vermillion and the nonkeratinizing epithelium of the labial mucosa is abundantly supplied with mucocutaneous end organs, with only a few in the labial mucosa. The mucoserous glands of the labial mucosa are richly innervated.

Adult↗
PubMed1975

The induction of melanogenesis by ultraviolet light in the pigmentary system of Rhesus monkeys.

Except for the face, eyelids, friction surfaces, and lips, the epidermis of the rhesus monkey contains no discernible melanocytes. After ultraviolet irradiation, however, dopa-positive dendritic cells appeared. With daily sequential irradiation, the number of histochemically demonstrable dopa-positive dendritic cells peaked after 30 exposures, then declined to a basal level which was maintained for the duration of the experiment (216 exposures or 43 weeks). Pigment cells can be restimulated by shading part of the irradiated area and then reirradiating after 3 months. While shaded, dopa-positive cells disappeared; but when reirradiated, they reappeared, increased, then declined again to a basal level. These melanocytes, unlike those in other primates, require high threshold levels of irradiation to produce a response, have a definite period during which they are active, and transfer very little melanin to the surrounding keratinocytes. Long-term ultraviolet irradiation has no discernible effect on dermal pigment-containing cells.

Animals↗
PubMed1975

Comparative study of the innervation of the facila disc of selected mammals.

The greatest concentration of sensory nerves in the muzzle and facial disc of mammals is in the nose. In most nocturnal mammals, these nerves penetrate the epidermis of the naked nose either or in bundles which resemble the corpuscles of Eimer. The hair follicles around the nose, lips, and eyes, as well as the heaviply innervated vibrissae follicles found in all hairy mammals except man, are well innervated; those elsewhaere are not. Everywhere on the human body both large and small follicles abound in sensory nerves. These morphologic observations suggest that in most mammals the most sensitivie areas of the skin are at the anterior and posterior ends (not reported here), and that human skin is better equipped for cutaneous sensibility than that of any other mammal.

Animals↗