Nihon Josei no Gaiseishokuki (External Genitalia of Japanese Females)

By Kanji Kasai. Tokyo: Free Press, 1995, 414 pages. Cloth, 30,000 Yen.

Reviewed by James W. Edwards, MA, MPH, MPhil, Transcultural Sexology Consultancy, 140 Charles Street, 19th Floor, New York, NY 10014.

Dr. Kasai, a university professor of gynecology, has produced a truly unique work, one that breaks a longstanding taboo: the publication of morphometric standards of normal variation in human genitalia. During 26 years of practice, Kasai clinically examined the external genitalia of more than 10,000 Japanese females and, with their consent, used a final sample of 8,330 for this statistical and photographic documentation. A browse through this study reveals significant morphometric variation, all the more remarkable because Japan is a highly homogeneous nation. Some historical background elucidates why Kasai has earned a place in the ranks of sexological pioneers.

In his classic--and still standard--work on human sexual anatomy, Dickinson (1949) lamented the paucity of research on normal genital morphometrics, a factor that influenced production of composite or "basic," rather than "normal" (p. 42), forms for male and female genitalia. Genital morphometric norms remain in the domain of general statements offered with little substantiation. Most exceptions are studies of males, but there has been an embargo on the publication of the underlying statistics. For example, some critical statistics of Schonfeld and Beebe's (1942, classic (and still standard) study on penile growth and size norms from birth to maturity were distributed privately by Schonfeld; the data reached publication 40 years later in an appendix to the work of other researchers (Money, Lehne, & Pierre-Jerome. 1984). Similarly, the self-reported penile data from the original Kinsey study remained unpublished until 1979 (Gebhard & Johnson, 1979). Masters and Johnson (1966) published summary penile data but, fearing untoward consequences, refused to divulge the full statistics on their male sample (Petersen, 1979). Even a recent medical book devoted exclusively to the penis (Hashmat & Das, 1993) contains no information on normal penile variation.

Texts on female genitalia are less rare. Indeed, female genitalia are overrepresented in reproductive chapters of general anatomy and physical diagnosis texts, a strong contrast to the underrepresentation of female images in nonreproductive chapters (Mendelsohn, Nieman, Isaacs, Lee, & Levinson, 1994). This greater willingness to depict female genitalia in the medical realm (as in popular culture) does not translate into more numerous studies of female morphometric variation. There are precious few data to compare with Kasai's study of Japanese females. The Masters and Johnson (1966) data sets are smaller, the emphasis is on physiological responses, and illustrations are primarily schematic drawings. Stereoscopic views, a user-unfriendly format, of normal clitoral variation appeared in a collection of sociological and medical essays on that organ (Lowry & Lowry, 1976). Feminists have sought to fill the gaps in the study of female genitalia (Chalker, 1996). Starting in the 1970s, Betty Dodson (1987) created and toured with a slide show of vulva, forms: and Joani Blank (1993) published a fine but small collection of photographs of the vulva. These self help guides for women, although showing the wide variety of form, have no statistical representation.

It is hardly news to readers of this journal that over the decades the most frequent and per during question from patients and the populace at large is some variant of "Are my genitals normal"'" This clamor for information has been answered by the scientific community with lots of reassurance but an astounding silence on authoritative investigation. The growing willingness to confront openly the problem of child sexual abuse has prodded the publication of photographic and statistical studies of variation in abused and nonabused immature genitalia (Berkowitz, 1992; Giardino, Finkel, Giardino, Seidl, & Ludwig, 1992; Heger & Emans, 1992), but adult variation remains veiled. Dr Kam has redressed this failure for Japanese women; in the process, he provides a base for future comparative study, for questions of ethnic/racial variation in genitalia have long percolated in scientific and lay Communities.

The language of publication, Japanese, constrains the accessibility of this work to a wide audience. However, those with a modicum of Japanese (or Chinese), or perhaps even none at all, will find Kasai's text somewhat accessible. Half the total pages are dedicated to color (the majority) and black-and-white photographs; page headings in both Japanese and English identify the anatomical parts illustrated. English is also used for chapter headings and subheadings. Throughout the text Kasai liberally uses English medical terminology (e.g., labia minora, glans clitoris, plateau and excitement phase), even though there are Japanese equivalents. Unfortunately, English was not used in the headings of the numerous statistical tables; still, with a little creative deciphering, tables of interest are identifiable, thus reducing demands on a translator.

Kasai includes chapters on the gluteal region and anus, changes in external genitalia during sexual responses, labia minora and majora, the clitoris, pubes, and the introitus. Kasai sought correlation on a number of parameters. Although not strictly within his topical purview, the lack of data on the vagina is made all the more regrettable by the completeness of analysis of his chosen focus. Kasai clearly states, and illustrates with diagrams, his standards of measurement and classification schemes, thus enabling comparative study and replication. The bibliography has 64 references, mostly in Japanese, with a few German and English sources as well (Japan and Germany have longer and more extensive historical records of genital morphometric research). An elaboration of why the study was undertaken, or a historical overview of genital research in Japan, is oddly lacking.

Although in a strict sense Kasai's sample may not be statistically representative of the Japanese population, it is the largest sample by far of any population's genital variance. The 8,330 females ranged in age from 15 to 46 years old, with normal endocrine values and regular menstrual cycles. Participants were enrolled at random in clinics and elsewhere: trial analysis at the stages of 2,000, 3,000, and 5,000 participants revealed similar statistical tendencies. Thus, it seems likely that had Kasai been able to capture an ideal random sample, the findings would differ little. That he was able to conduct and publish this work is ironic and remarkable: Japan's censors are diligent in blacking out the pubic area both in pornography and studies of classic erotic arts. To get distribution approval, Kasai and the publisher had to apply to the national police for an exemption on medical grounds. Perhaps others, with similar or lesser obstacles in their path, will be encouraged to follow Kasai in lifting the veil of secrecy cloaking genital variation.

References

Berkowitz, C. D. (1992). Child-sexual abuse. Pediatrics in Review, 13, 443452.

Blank, J. (1993). Femalia. San Francisco: Down There Press.

Chalker, R. (1996). A comparative study of the clitoral anatomy. In S. Matsumoto (Ed.), Sexuality and human bonding (pp. 315-321). Amsterdam: Elsevier.

Dickinson, R. L. (1949; 1971 reprint). Human sex anatomy. Huntington, NY. Robert E. Krieger.

Dodson, B. (1987). Sex for one. New York: Harmony Books.

Gebhard, P. H., & Johnson, A. B. (1979). The Kinsey data: Marginal tabulations of the 1938-1963 interviews conducted by the Institute for Sex Research. Philadelphia: W. B. Saunders.

Giardino. A. P. Finkel. M. A., Giardino. E. R., Seidl, T., & Ludwig, S. (19921. A practical the evaluation of sexual abuse in the prepubertal child. Newbury Park. CA:

Hashmat, A. I., & Das. S. (1993). The penis. Philadelphia: Lea & Febiger.

Heger, A., & Emans, S. J. (1992). Evaluation sexually abused child. New York: Oxford University Press

Lowry, T. P., & Lowry. T. S. (1976). The clitoris. St. Louis: Warren H. Green.

Masters, W. H., & Johnson. V. E. (1966). Human sexual response. Boston: Little, Brown.

Mendelsohn. K. D., Nieman. L. Z., Isaacs, K., Lee, S., & Levison. S. P. (1994). Sex and gender bias in anatomy and physical diagnosis text illustrations. Journal of the American Medical Association, 272, 1267-1270.

Money, J., Lehne, G. K. & Pierre-Jerome, F. 11994). Micropenis: Adult follow-up and comparison of size against new norms. Journal of Sex & Marital Therapy, 10, 105-116.

Petersen, J. R. (1979). Playboy interview: Masters and Johnson. Playboy, 26(11), 87-122.

Schonfeld, W. A. & Beebe, G. W. (1942). Normal growth and variation in the male genitalia from birth to maturity. Journal of Urology, 48, 759-777.