Latest SpermatologyBook Review
Kazuo Inaba / Supervisor, Masato Ikawa, Naoaki Kuji, Kentaro Tanemura, Manabu Yoshida / Editors, University of Tsukuba Press, First edition published December 2025, 12,650 yen (tax included)
Zoology researchers are frequently confronted with the question, "Is basic research useful to society?" Because research is conducted with the support of sponsors, many zoology researchers are forced to succinctly explain the significance of their own work. In fact, if the explanation of significance or spillover effects in a grant application is lukewarm, acceptance cannot be hoped for. On the other hand, there is also the aspect that foreseeable significance is quite limited. Indeed, those who have achieved great things often look back at the "unexpectedness" of their initial results and the "unforeseen breadth" of their subsequent development. This could be said to be the appeal of science as an enterprise, but considering the cold sensation that crosses the back of the neck—(Will this be useful?)—at the fleeting moment when a researcher with nothing to look back on is engrossed in shouting "This is so interesting!", this question feels like an occupational disease. Yet, as it turns out. Reading this book, what struck the reviewer's heart most realistically was the sentiment, "Basic research is terribly useful...", a realization that makes one wonder if it's okay to be saying such a thing at this late stage.
This book comprehensively cuts across sperm from the perspective of ions to the universe. Part 1 introduces our current understanding of sperm formation, motility, and fertilization, while Part 2 presents various examples of sperm morphology and function, as well as sperm storage and reproductive strategies. Although these are familiar topics to members of the Zoological Society, the reviewer also learned a great deal. The diversity of SRY, the cycle and wave of spermatogenesis, recombination during meiosis, crossover interference, lumicrine and epididymosomes, rheotaxis and collective swimming, SEMGs/SVS2 and PSA, acrosomal vesicle pH elevation, UTJ, Fer-1, CD9 and microexosomes, sCS, physiological polyspermy, the bee sperm pump, sea slug penis autotomy and breakage, and so on. I encountered many stimulating discoveries and issues.
The importance of this book likely lies in the fact that Parts 3, 4, and 5 are bound within the same volume. Parts 3 and 4 introduce rapidly evolving topics such as male infertility, reproductive medicine, and fisheries and livestock technologies involving sperm, while the final Part 5 discusses the spatiotemporal overcoming of sperm and the genetic information contained within them. This second half was also a continuous series of surprises and learnings. How human bipedalism appears to be partially related to male infertility. The selection of sperm based on rheotaxis using microfluidic devices. The reality of fertility treatment and "disclosure." Testing and treatment for male infertility. Methods of male contraception. Culture methods. Examples of technology application in fisheries and livestock settings. The sorting of male and female offspring. The reviewer, in particular, was astonished by the sex-sorting method targeting TLR7 and TLR8, and further astounded by freeze-dried (FD) sperm and its high resistance. Moreover, I felt deeply and meaningfully, step by step, that the contents of this second half are unquestionably supported by the explanations provided in the first half.
I think, after all, sperm is of great importance. On a personal note, back when the reviewer was still young, taking advantage of having free access to a high-end differential interference contrast microscope all alone in the lab late at night, I decided to observe various cells of my own. Hair roots and oral mucosal cells were just an "hmm," and blood cells made me go "Oh!", but sperm... its presence was somewhat overwhelming. Although they were my own cells, they wriggled, creating a subtle sense of otherness, and looking at them dispassionately, they weren't much different from those of a sea urchin... yet I still found myself caring about their abundance and activity... and chose not to go out of my way to talk about it openly with others. Sperm is thus intimately close, extremely personal, and yet at the same time represents the very future of humans, food resources, and all other life forms. While it sometimes gives rise to urgent personal and social issues, tied up as it is with a sense of shame, it tends to be hidden away within society. Precisely for this reason, there is great persuasiveness in a format where bioethics is gradually revealed amidst the multifaceted analysis of sperm within a scientific context. I was left with a strong impression by how the "Conclusion" at the end of the book symbolically conveys the significance of spermatology and its importance for the future of society; it is widely worth a read. Basic research is truly useful.
Another point I would like to make is that this book has been compiled in a completely revamped format and content, yet building upon the academic books "Spermology" (1992) and "New Spermology" (2006), which reflected the latest knowledge of their respective times. By comparing these two books with the current volume, the reviewer also came to witness how much the image of sperm as a research subject has been updated, deepened, and transformed, while continuing to exist right before the eyes of researchers since Leeuwenhoek. Naturally, the 2025 "Latest Spermology" contains many descriptions of the most recent findings. However, the 1992 "Spermology" also certainly contains a great number of contents that make a reader exclaim "Wow!" and "Oh!" (especially the descriptions of the history of research and the beauty of the illustrations are magnificent!). Knowledge accumulates, but books do not necessarily grow thicker. Within the framework surrounding sperm already established by "Spermology" (1992)—namely "Research History / Morphology / Formation / Motility / Fertilization / Diversity / Medicine / Technology / Ethics"—it stands out how the contents have been renewed into something that can only be called "Latest Spermology," in step with the progress of society. The eras themselves are inadvertently reflected through the compilation of these books driven by the passion of the field's leaders in each respective period. Regarding these three volumes, one can understand that the Zoological Society was an important site for that passing of the baton, and one might also look forward to the next generation taking over this book as a meme. In the context of researchers, "spermology" is also sperm itself. It seems to be an endeavor that other fields can also emulate.
Finally, while the "Glossary" at the end of the book is wonderful in both its concept and selection of terms, I felt it was difficult to correlate it with the descriptions in each chapter without reading the entire thing. It seems it would have been more effective if there had been some kind of cross-referencing, such as a clear rule for the order of the glossary entries, chapter numbers associated with each term, a list of terms explained at the end of each chapter, or the inclusion of "Glossary" page numbers in the index.
Atsuo Nishino (Faculty of Agriculture and Life Science, Hirosaki University)
