Aristotle Imagine you are Aristotle living in Greece in 350BC What makes you an important person in the discovery of mammalian ova? I am one of the greatest philosophers and teachers of my time. This is what I wrote about reproduction, Animals have this in common with vegetables, some of them arise from seed others arise spontaneously. Plants either grow from the seed of other plants or spring up spontaneously - having met with some primary condition fit for their evolution. Some of them derive their nourishment from the ground, others arise from other plants. Equally some animals are engendered from cognate forms and others arise spontaneously – from the earth or from putrefying vegetable matter, others are produced in animals themselves, from the excrementitious matters of their parts I divided animal into two classes, those which develop without parents – by spontaneous generation and those which are generated by sexual reproduction. In female mammals the embryo is formed in the uterus from a mixture of menstrual blood and male semen Years of observations by myself and my students. We constantly ask question about the nature of things and our observations help us to reason and think about the solution. Remember: the biologists of Aristotle's day were quite accustomed to the thought that many creatures develop in decaying organic matter Claude Galen Imagine you are Claude Galen Working in Italy in 150AD I am a philosopher and have been a medical doctor to several emperors in Rome. I have dissected and studied the bodies of many monkeys and pigs. I have studied widely and with some of the greatest physicians of my time. I believe that male semen is made in the arteries and veins and strained by the testes. The female semen is likewise made in the ovarian vessels and separated in the “female testes”. From here it is carried by the fallopian tubes to the uterus. These male and female fluids are mixed in the uterus, they coagulate, become frothy and evolve the embryo. Note: Doctors accepted Galen’s finding for over 1000 years after his death. Andreas Vesalius Imagine you are Andreas Vesalius living in Padua in Italy in 1550AD What makes you an important person in the discovery of mammalian ova? I am an anatomist and a physician. I have upset the medical establishment by basing my work around the dissection of human bodies. Many of the bodies I took down from the scaffold during the night. 500 years ago I published one of the most influential books on anatomy ever written. It is still on sale today in 2015. I have described vesicles and yellow bodies in the female testes, and I have described the structure of the fallopian tubes very accurately. I have dissected and described the structure of male and female reproductive organs. Gabriello Fallopio Imagine you are Gabriello Fallopio Working in Italy (Padua) in 1570 I am a pupil of Vesalius. I have also observed vesicles in the ‘female testes’ Although I have looked for eggs, I have only seen a clear fluid inside the ‘female testes’. I have studied in great detail the Fallopian tubes. My diagrams are so carefully detailed that these tubes have been named after me by my peers. As for the function of these fallopian tubes they appear be vents to conduct noxious vapours from the uterus. Hieronymous Fabricus Imagine you are Hieronymous Fabricus Working in Italy in 1598 I am a pupil of Gabriello Fallopius, I have decided to carry out a scientific study, in a systematic way to try to solve the problem of reproduction. I have published many pictures of developing embryos which I obtained by incubating hen’s eggs for different lengths of time. These are the first such drawings ever published. I have made the most of new printing technology. I have great respect for Aristotle. I have given the name Ovarium to the organ in hen’s which produces eggs. No more use of the words ‘female testes” thanks to me. But of course you know that eggs are formed in the uterus, as Aristotle describes, and the ovarium is obviously just a part of the uterus. William Harvey Imagine you are Wiliam Harvey working in Oxford in 1640 I have studied with Heironymous Fabricus in Italy. He is a great teacher, in fact it was in his lessons that I learned about valves in the veins as well as seeing hundreds of egg . I have been studying egg embryos myself in the university in Oxford. I am physician to King Charles I, and I often accompany him on deer hunting trips. He lets me dissect the female deer and I share my findings with him. Mammalian reproduction is quite different from chickens. I have described the uterus and the Fallopian tubes of deer in many chapters of my book. I also have studied the ovaries, those glands (Ovarium) which were named by my teacher in Italy. You know the breeding season of deer is very short, and thus I have been able to obtain deer killed by our King Charles, which I know to be between six to eight weeks after the breeding. In these animals I have searched for signs of the generation of the embryo, the eggs. I expect to find the embryo developing in the uterus as Aristotle and Galen have taught us. But it’s been many years of study now and I have dissected the uterus of many deer. In all these studies I have only found the uterus to be empty. There is nothing in it that the eye can see until one month after mating. The uterus lining is swollen and soft but there are no contents. I have shown this to the king himself. In fact we had a great debate about this. The deer I have studied at later points after copulation do contain white filaments, like spider webs, they look like gelatinous sacks. And a few days later I can see tiny embryos. I have denounced the spontaneous generation theory of Aristotle and Galen I am convinced that even maggots and worms have some origin in eggs. I published my new doctrine ex ovo omnia, meaning that all life originates from an egg. I have been looking for eggs in deer (as supporting evidence for this) but without success. Regarding the mechanism of reproduction, I have concluded that the male semen doesn’t reach the uterus, but sends up an “effluvium” which stimulates the uterus to secrete an egg, first this is a something with no body, then it becomes a filamentous web and finally it forms into an embryo. I wrote, “The process of forming an egg in the uterus is comparable to the formation of an idea in the brain, just as an artist can paint a landscape from memory so the uterus can produce an egg.” Regnier de Graaf Imagine you are Regnier de Graaf Working in the Netherlands in 1670 I have published three books about the anatomy of reproduction. In the third book I have explained and proved the idea that the “female testis” is an ovary I have also provided the fullest description yet of the female genital tract all of my descriptions are illustrated with clearness and accuracy, including the fallopian tubes. My description of the ovary includes an account of the corpus luteum and the ovarian follicles. The scientific community like my description so much these follicles are already known as “Graafian follicles.” I believe that the whole content of the follicle is the ovum. I have followed the systematic methods of Harvey, and I have observed rabbits from the time of mating through the gestation period. I disagree with Harvey, I have seen tiny spherical bodies in the fallopian tubes and larger spheres in the uterus. This is proof that the embryo is not formed in the uterus, but it is the product of the ovaries which moves to the uterus, growing as it travels. Jean Baptiste Dumas Imagine you are Jean Baptiste Dumas Working in Geneva in 1827 I have done a lot of work in Geneva with Jean Louis Prévost We have together applied exacting chemical methods in our research about reproduction. We have the advantage of all the other researchers that we can observe our material using the newly invented microscope. We have proved that sperm cells are made in the testes. We have mixed frog eggs and frog sperm cells together and achieved ‘in vitro’ fertilization. We have found sperm cells in the uterus of dogs after copulation. This is definite proof that Harvey was wrong about no semen passing into the uterus. We have seen the vesicles in the ovary containing Graafian follicles. We did describe small round bodies but don’t think they are important. What we haven’t been able to find is the female egg (ova) (NOTE: If only they hadn’t overlooked these small round bodies, as they were probably ova ) Karl Ernst von Baer Imagine you are Karl Ernst von Baer Working in Estonia in 1827 I am born in Estonia, and work as a professor of zoology and anatomy in the university. I was lucky early in my career to discover the mammalian ovum. I was studying embryology of dogs, just a variation in the work of Harvey and Dumas I was about 33 years old, and I had the good idea of looking at progressively smaller and smaller embryos. This was deliberate planning, so that I knew what to look for, as the embryos get smaller and more difficult to see. Of course I was using microscope. I observed and described blastocysts (hollow balls of cells) attached to the walls of the uterus. Then in my next samples I saw free blastocysts in the fallopian tubes. Then I looked inside the ovary, In my lab book I wrote, “I opened one of the follicles and took up the minute object on the point of my knife, finding that I could see it very distinctly and that it was surrounded by mucus. When I placed it under the microscope I was utterly astonished, for I saw an ovule just as I had already seen them in the tubes, and so clearly that a blind man could hardly deny it.” It is truly wonderful and surprising to be able to demonstrate to the eye, by so simple a procedure, a thing which has been sought so persistently, and discussed ad nauseam in every text-book of physiology for 2000 years The greatest reward of the scientific investigator is, that no matter what his success or failure, he knows that he can serve by merely keeping on asking questions; if he cannot answer them someone else will, and in the end truth is achieved, and mankind advanced a little farther toward the light.
