Penile Spines

The post-natal development of penile spines, their appearance in adult males, and the changes that occur in them after castration, after treatmellt of castrated males with testosterone propionate, and after cessation of hormone treatment were studied using both pre and postpuberal castrates. Most of the observations were made on live animals and the conditions of the spines were correlated with levels of sexual activity using data from mating tests with estrous females. In all the conditions of testing, the spines increased in size as the androgen level increased, and decreased in size as the androgen level fen. These changes correlated positively with the rise and depression of mating activity as the androgen levels increased or decreased. The relationship, however, was not always consistent in that sexual behavior declined rapidly in some castrated males before the spines started to decrease in size, and in other castrate6 males, sexual behavior persisted long after the spines had disappeared. While our data are not inconsistent with the hypothesis that loss of spines leads to reduced stimulation of the penis during intromission and hence to a decline in sexual arousal, it emphasizes that the great variability in sexual behavior after castration must be due to other causes. The glans penis of the male cat is covered by relatively large, pointed, horny spines or papillae. These spines are sensitive to androgens, and they are the only known external indicators of the level of male hormone in cats. Several descriptions of the penile spines of the intact domestic cat and other felines appear in the older literature which has been summarized by Retterer and Leligvre ('14). The spines were not present in three postpuberally castrated male cats that were examined 3 or 7 years after operation (Retterer, 1887; Retterer and Lelikvre, '12). Reisinger ( '37) , on the other hand reported no changes in the spines of a male one year after postpuberal castration, but two other males prepuberally castrated at the age of one and two months did not have spines when examined at 12 years and 16 months respectively. Spines or papillae of similar nature, but much smaller and more numerous, are also found on penises of laboratory rats and other rodents. After castration these papillae disappeared at approximately the same rate as sexual behavior declined (Beach and Levinson, '50). Likewise, small doses of testosterone given to casANAT. REC., 157: 71-78. trates, maintained a small number of papillae and low levels of mating, while larger doses of hormone maintained more papillae and higher levels of sexual behavior. Since numerous touch corpuscles are located directly beneath the base of the papillae, these investigators concluded that the effects of castration upon sexual behavior in the male rat are due in some measure to lowering of tactile sensitivity in the glans penis as a result of deterioration of the genital papillae. During a long term study of the endocrine relationships of sexual behavior in male cats (Rosenblatt and Aronson, '58, '58a; Cooper and Aronson, '58; Rosenblatt, '65; Aronson and Cooper, '66) we examined many living cats for the appearance of the spines, recording these photographically and by verbal description. Since even brief inspection involved restraining the animal and retracting the prepuce, while careful examination and 1 Supported in part by grants from the Committee for Research in Problems of Sex, National Research Council. and -ant HD-00348. National Institute of Child Health and Human Development. Students of the Undergraduate Research Participation Program. supported in part by the National Science Foundation, current grant GY-350, assisted in the research. The histological preparations were made by Mrs. A. Mane Tucker. We wish to thank Dr. Ethel Tobach for reading the manuscript and for helpful suggestions.