A MICROANATOMICAL STUDY OF THE RESPONSE OF THE PILOSEBACEOUS APPARATUS OF THE RABBITS EAR CANAL

[摘要] The smooth skin of the external auditory canal of the rabbit has large complex sebaceous glands with single large hairs rather than fur, but has no apocrine (cerumen) glands and therefore offers a useful site for experimental observations on the pilosebaceous apparatus. In addition, the ease with which whole mounts of this skin can be prepared simplifies visualization of the hair cycle or measurement of sebaceous gland size. The healing of a surgical defect at this site frequently resulted in the formation of keratinous cysts. Furry hair tufts probably originating from the furry skin of the external surface of the ear sometimes appeared in the scar sites. Fractional superficial X-ray therapy (100 r/week for 11 weeks) failed to disturb normal sebaceous gland growth. A single dose of 2000 r caused a decrease in sebaceous gland size but induced a hyperplasia of the epidermis, the follicular epithelium and the sebaceous gland ducts. Chloronaphthalene topically applied in acetone caused a mild dermatitis but a striking follicular accentuation within 3-5 days. The microscopic changes included thickening of the epidermis, the epithelium of the follicles and the sebaceous gland ducts; a severe destruction of the sebaceous gland acini; and thickening of the dermis. Prolonged application produced hyperkeratosis with follicular plugging (comedones) and disappearance of sebaceous glands. Gradual recovery followed discontinuance of application of chloronaphthalenes. Testosterone propionate given parenterally to male and castrate female rabbits caused an increase in sebaceous gland size; progesterone and 17-hydroxyprogesterone in castrate females produced no changes differing from those in the control animals injected with peanut oil. Neither testosterone nor progesterone caused demonstrable thickening of the epidermis.