摘要:

Macroscopic observations on the expression of two mutant alleles ("hairless" and "rhino") in the house mouse, and on their interaction with one another and with a third mutation ("Naked") producing hypotrichosis of a different type, have been described. In hairless mice the juvenile pelage falls out and the skin shows little wrinkling; rhino mice lose their hair in a similar way but subsequently develop an intense wrinkling of the skin. Naked mice lose their hair by a breaking-off rather than a falling out, and show a pattern of alternate depilation and regeneration of the hair coat.Hairless/rhino hybrids lose their hair according to the hairless pattern, but later manifest a characteristic wrinkling like, but not as extreme as, that of the rhino mutant, "rhino" is therefore not completely recessive to "hairless."There are thus three basic grades of wrinkling—hr/hr,hr/hrrh,hrrh/hrrh—determined by the factors present at theHrlocus. The presence of the heterozygous Naked factor in any of these types causes an intensification of its degree of wrinkling. This intensification is even more pronounced when the Naked factor is homozygous. Moreover, the "Naked" characteristics are themselves exaggerated in these compounds, the intensification being proportional to the degree of wrinkling.These results will be interpreted in the light of histological findings to be presented in the following paper.

ISSN:1923-4287    

DOI:10.1139/cjr46d-001

出版商:NRC Research Press    

年代:1946

数据来源: NRC

摘要:

The first visible abnormality in the skins of homozygous rhino mice is a hyperkeratosis of the epidermis and follicle neck wall at the time when active growth of the hair ceases. This is associated with a widening of the hair canal (due to a lateral expansion of the hyperplastic layers of the follicle neck) and a subsequent irregular shortening of the follicle. The cause of hair loss is considered to be the widening of the hair canal and consequent lack of the support supplied by the normally tight-fitting follicle neck when shortening of the follicle raises the base of the hair to a level just below the proximal end of the hair canal. The hyperplastic tendencies of the epidermal derivatives are further expressed by (a) the development of hair canal cysts (utriculi), which leads to an increase in the surface area and a consequent wrinkling of the skin, (b) the formation of sebaceous-gland and follicle-end cysts, which cause the thickening of the epidermis, and (c) overgrowth of the nails.Hairless (hr hr) mice show a similar, but less extreme, tendency towards hyperplasia, and the histological character of the skins of hairless/rhino hybrids is intermediate between that of the rhino and hairless types.Mice of any of these types (hr hr,hrrhhr,hrrhhrrh), which are also heterozygous for the Naked factor, show an exaggeration of both the follicular keratosis and the Naked characteristics. In mice homozygous for the Naked factor the exaggeration is more extreme.Transplantation experiments show that rhino skin adjacent to normal skin behaves non-autonomously, indicating that rhino skin cells are able to utilize but cannot produce some substance necessary for the maintenance of normal stratified squamous epithelium; this substance is produced by normal skin cells but is not present in the blood stream of normal mice.Results of an attempt to discover a relationship between the mode of action of the rhino mutation and the metabolism of vitamin A by feeding rhino mice massive doses of vitamin A were inconclusive.

ISSN:1923-4287    

DOI:10.1139/cjr46d-002

出版商:NRC Research Press    

年代:1946

数据来源: NRC