The Discovery of Egg and Sperm in the 17th Century - Phenix-Vet

4 M CobbSociety in London (Swammerdam n.d.). Although neitherman had yet provided any clear evidence that humanovaries contained eggs, they were now on a collisioncourse.De Graaf apparently won the race when, in March1672, he published his brilliant De Mulierum OrganisGenerationi Inservientibus Tractatus Novus (New treatiseconcerning the generative organs of women) (De Graaf1672; Jocelyn and Setchell 1972). Although the bookcontained dissections of humans, rabbits, hares, dogs,pigs, sheep and cows, its decisive part was a section onrabbit mating and pregnancy. Here, de Graaf referred tothe follicles or their contents as eggs, and gracefully gavehis former teacher, van Horne, the credit for thisdiscovery, pointing out that Steno had merely said thatovaries contained eggs without identifying them. Aboveall, de Graaf used careful experimental dissection toshow that in rabbits the follicles reddened and rupturedfollowing mating and that 3 days after copulation, smallspherical structures could be found in the Fallopiantubes. De Graaf emphasized that the number of thesespheres was generally identical to the number of rupturedfollicles and that it never exceeded them. Because matinginduces follicular rupture in the rabbit, de Graafmistakenly suggested that the same thing must happenin women, which would imply that virgins would showno ruptured follicles. Finally, like Harvey, de Graaflooked for signs of semen in the uterus and Fallopiantubes, but could find none. He concluded that only a‘seminal vapour’ reached the eggs and fertilized them.Through his experimental work, de Graaf showed thepower of the scientific method, and also demonstratedthat mammals – including women – have eggs.In response, in May 1672, Swammerdam publishedhis own account of human generation, MiraculumNaturae, sive Uteri Muliebris Fabrica (The miracle ofnature, or the structure of the female uterus) (Swammerdam1672a,b). This contained no experimentalstudies, merely a great deal of dissection, some of whichwas highly pertinent, as it showed that virgin womenalso have ruptured follicles. Swammerdam also exploredthe very real problem of how the fluid in the follicle –which he felt was the egg – could move from the ovaryacross into the Fallopian tube. But the central themewas Swammerdam’s claim that van Horne had been thefirst person to accurately describe the female reproductiveorgans and that he, Swammerdam, had firstsuggested that the egg was in the follicle. The bookclosed with a polemical appendix, in which Swammerdamsneered at the quality of de Graaf’s drawings andeven at the fact he had studied ‘rabbits and bruteanimals’ rather than humans, thereby inadvertentlyshowing that he had entirely missed the point of deGraaf’s work. Swammerdam dedicated his book to theRoyal Society, and sent it off to London, followed by abeautifully preserved human uterus, along with twelveother items of genital anatomy, both male and female.Above all, Swammerdam asked the Royal Society toadjudicate on who had the priority in stating thatwomen have eggs.Less than a year later, as the Dutch Republic waswracked by a murderous invasion by the French in theopening battle of a war that lasted 6 years, de Graafproduced a blistering response to Swammerdam, PartiumGenitalium Defensio (Defence of the genital parts)(De Graaf 1673a,b). This savage polemic – written in theimmediate aftermath of the death of de Graaf’s montholdbaby son, Frederick – reproduced letters between deGraaf and Swammerdam, quoted conversations andmade accusations that far exceeded anything seen in amodern row on the internet. De Graaf flatly denied thathe knew that Steno had ever published about eggs (thetwo men had in fact corresponded on the questionseveral times), and accused Swammerdam of plagiarismand of piling ‘lie upon lie’. De Graaf then sent what headmitted was a ‘not very polite’ book to the RoyalSociety and, like Swammerdam, asked them to judgewho had priority.In response to the pleas from the excitable Dutchmen,the Royal Society set up a three-man committee to dealwith the fractious dispute. When the committee eventuallyreported, in October 1673, they decided that neitherde Graaf, nor Swammerdam, nor van Horne had beenfirst to discover that women have eggs. That honour,they stated, went to Steno. This verdict turned out to becompletely pointless. A week before the committeecompleted its work, de Graaf died, aged only 32.Swammerdam wrote an immediate reply, of which notrace remains, and then never referred to the matteragain. Steno, meanwhile, was on the verge of abandoningscience to become a Catholic bishop, and there is noevidence he ever heard of his ‘victory’. Even the RoyalSociety seems to have lost heart, for the report was notpublished for more than 80 years (Birch 1756–7).Ironically, history has adopted a very different view:the follicles are now known as Graafian follicles and thepart played by Steno, Swammerdam and van Horne isforgotten to all but a handful of historians.Whatever the ins and outs of the priority dispute, thekey issue was that by the mid-1670s, the ‘egg theory’came to dominate. In 1679, the French scientificpublication Journal des Sçavans wrote: ‘The view thatman, as well as all other animals, are formed from eggsis something that is now so widespread that there arehardly any new philosophers who do not now accept it’(Anonymous 1679). However, even as the ink wasdrying on the page, an amazing new discovery waschallenging that view, and would once again throw thescientific community into turmoil.Enter the SpermWhen Reinier de Graaf sent his polemical book to theRoyal Society in April 1673, he included a report whicha friend of his, ‘a certain very ingenious person namedLeeuwenhoek, has achieved by means of microscopes’(De Graaf 1673a,b). Leeuwenhoek’s brief letter includeddescriptions of a bee sting, a louse and a moss. This wasthe beginning of a long relationship between Leeuwenhoekand the Royal Society, which spanned the next50 years and consisted of nearly 200 letters from theDutchman (Dobell 1932).Unlike de Graaf, Steno and Swammerdam, Leeuwenhoek(he later adopted the prefix ‘van’ as an affectation)was not academically trained. He was a draper, who hadbegun making his own single-lens microscopes forÓ 2012 Blackwell Verlag GmbH