Prior to the publication of Vesalius's De humani corporis fabrica in 1543 [1], the study of anatomy had made slow progress in comparison with other branches of medicine during the Renaissance. Even the invention of printing by Johann Gutenberg around 1450 did not result in an immediate explosion of anatomical texts and illustrations. The importance of Vesalius's book cannot be understated, for it not only provided the textual basis for a new scholarly approach to anatomy, it also heralded the beginnings of anatomical illustration based on direct scientific observation. Vesalius was, moreover, fortunate in his choice of artist, for the woodcut illustrations that adorn his great work are notable not only for their accuracy, but also for their enormous artistic merit, which set the standard for all anatomical illustration that followed.

In the introductory essay to Mortimer Frank's English translation of Ludwig Choulant's Geschichte und Bibliographie der anatomischen Abbildung, the distinguished historian of science, Charles Singer, usefully divides the history of anatomical illustration into six discrete periods. According to his scheme, the first phase embraces a period of almost two millennia, from ancient antiquity to the immediate precursors of Vesalius.

Little is known about the study of anatomy in the ancient world, but it is certain that human dissection was carried out around 300 B.C. in the Greek colony of Alexandria in Egypt, where a medical school flourished for several centuries, and a great library was formed. In the second century A.D. the Greek anatomical legacy was codified by Galen (ca. 129-199), whose own writings were firmly grounded in the Alexandrine tradition. Galen, a Greek physician practising in Italy, wrote several works on anatomy. Galen's anatomical observations, however, were based on dissections performed on animals, usually pigs and apes, which were then indiscriminately applied to human anatomy.

Following the Arab conquest of Alexandria in 642, many Greek medical texts came into Arab possession, and were translated and studied. In this way the medical tradition of the ancients was preserved during the Middle Ages, but little was added to the canon. The main obstacle to progress of anatomical knowledge during this period was the proscription of post-mortem dissections under Islamic law. To Muslims even the representation of the human body was strictly forbidden. In the West, the Christian church, too, was strongly opposed to dissection.

The late Middle Ages witnessed the emergence of universities in Europe, the earliest being at Bologna in 1158, and Montpellier in 1181. By the end of the thirteenth century major centres for the teaching of medicine had been established at Bologna and Salerno in Italy, and at Montpellier and Paris in France. Teaching was based on Arab sources derived from the Galenic canon, and practical anatomy was based on the dissection of animals. It was not until the latter part of the thirteenth century and particularly in the fourteenth century that the civil and ecclesiastical laws governing dissection were relaxed. In 1303 the first recorded judicial autopsy was carried out in Bologna, and by the end of the century public dissections were being legally performed at Venice, Florence, and Montpellier. In 1405 Bologna was permitted to perform periodic public dissections, while Padua, destined to become the leading centre of anatomy in the sixteenth century, received official sanction for the same in 1429.

Despite the fact that dissections were fairly widespread by the mid-fifteenth century, progress in anatomical illustration was negligible. Typically, anatomical figures consisted of crude schematic drawings, often based on astrological factors [2], but certainly not on scientific observation, and were, therefore, practically useless as serious teaching instruments. At the same time anatomical dissections were also being carried out in private by artists, sometimes in conjunction with anatomists, but such activities were preparatory exercises for paintings, not contributions to the corpus of anatomical illustration as a scientific discipline.

This was the situation in the mid-fifteenth century, when Gutenberg's revolutionary invention transformed the world of scholarship and learning. In the first fifty years of printing, many medical texts were issued, but few of them were illustrated. The first medical text with illustrations of any significance was Johann de Ketham's Fasciculus medicinæ, printed at Venice in 1491. And yet the anatomy displayed in this frequently reprinted work was medieval in character, and did little to advance knowledge of the discipline [3].

The second phase in the history of anatomical illustration was a very short period of approximately twenty years, beginning in 1521 with the works of Giacomo Berengario da Carpi, and ending in 1543 with the publication of Vesalius's landmark work. This phase is characterised by attempts at a more scientifically based anatomy, exemplified by Berengario da Carpi's works on anatomy which marked a departure from the purely schematic and allegorical towards a more accurate rendition. To this category also belong the illustrations contained in the works of Dryander, whose woodcuts of the head achieve a hitherto unprecedented verisimilitude [4].

Anatomical illustrations in books from this period were exclusively woodcuts, which reached a remarkable degree of perfection, particularly among Italian and German practitioners. An artistic conception of formal beauty and aesthetically pleasing images emerged, that became the norm for anatomical illustration, and which endured for several centuries. Characteristics of the prevailing artistic schools of the day are often evident, as, for example, the Mannerist touches of Charles Estienne's anatomy [5]. Another feature of illustrations of this period was the tendency towards representing the whole body rather than its individual parts.

The next phase covers over eighty years, and extends from Vesalius to 1627. Enormous increase in anatomical knowledge, thanks mainly to Vesalius, was made during this period. The correction of errors and new anatomical discoveries were reflected in splendid illustrations, frequently displayed against a landscape background. Figures displaying skeleton and muscle were shown in idealized form, and appear not as cadavers, but as living human beings striking dramatic poses [6]. The remarkable achievement of the Italian school of anatomy was soon imitated both within and beyond Italy. Vesalius's illustrations were widely copied, though probably in respectful acknowledgment of their merit, rather than as blind acts of plagiarism. The anatomical writings of Valverde, Geminus, du Laurens, and Bauhin, all represented in Anatomia, were among the most prominent of the Vesalian imitations.

Just as the art of the woodcut was reaching its apogee, copper plate engraving and etching, with its greater potential for more accurate, detailed representation, began to replace woodcuts as the principal medium of anatomical illustration.

The primacy of copper plate illustration prevails into the fourth phase of anatomical illustration, a period of more than a century, between 1627 and 1730s. It begins with the posthumous publication of Giulio Casseri's Anatomia anatomicæ, a projected anatomy of the entire human body; the plates were reissued in 1631 to illustrate Spiegel's De humani corporis fabrica libri decem. Frequently grotesque [7], they represent the first original set of anatomical illustrations to be published since Vesalius.

Towards the end of the seventeenth century scientific accuracy was sometimes sacrificed for artistic considerations. The plates of Bidloo's anatomy [8], drawn by Gérard de Lairesse, are magnificent works of art, and yet contain numerous anatomical inaccuracies. They were issued, moreover, with the slimmest of texts (this deficiency was partially remedied in Cowper's unauthorized version of the Lairesse illustrations, issued with a new, more detailed text). This period also saw the publication of Aselli's De lactibus (1627), which not only announced the discovery of the lacteal vessels, but also represents the first attempt to use colour to distinguish different parts of the body - in this instance the lacteal vessels from the blood vessels and viscera, with the aid of a colour-printed chiaroscuro woodcut. It was also during this period that Eustachi's splendid engraved plates, lost for 162 years, were rediscovered and issued for the first time in 1714 [9].

The fifth period, from 1730s to 1778, is dominated by the commanding figure of Albinus, doyen of the Leiden medical school, who like Vesalius, established a new method of anatomical illustration. Albinus's anatomical figures are composites of masses of observations [10]. He insisted on the greatest exactness of detail, attained through the use of various measuring instruments and painstaking draughtsmanship. In order to achieve this end, he employed a great artist, Jan Wandelaar, to execute the drawings under his close supervision. The resulting plates, combining great scientific accuracy with artistic accomplishment, became the new norm eventually replacing the Vesalian images that had been the mainstay of anatomical illustration for over two hundred years. Albinus's methods soon spread beyond the borders of the Netherlands, particularly to Britain, where they are evident in the plates prepared by Jan van Rymsdyk for William Hunter's Anatomia uteri humani gravidi (1774) [11] and for the anatomical atlases of others. The vital role of the artist, rather than the anatomist alone, begins to be increasingly acknowledged, and the names of the artist and even the engravers sometimes feature prominently on title pages or in preliminary matter.

The introduction of colour-printing begins in this period, but Gautier d'Agoty's striking life-size mezzotint plates are no more than curiosities that add little to anatomical knowledge [12]. The great potential of colour in the methodology of illustration was not fully realised until a later period.

The publication in 1778 of Soemmering's De basi encephali [13] marks the beginning of the final phase, which extends to the mid-nineteenth century. During this period collaboration between anatomist and artist is at its closest. Indeed, many anatomists, such as Soemmering, Charles Bell, Camper, Carswell, and Maclise, were also accomplished artists and drew their designs, while John Bell both drew and engraved many of his. Scarpa employed and trained his own artist, Faustino Anderloni, and supervised his work.

A characteristic of this phase is a greater shift towards the anatomy of the internal organs, in the light of new discoveries made as a result of more specialized study. At the same time new methods for preserving anatomical specimens were devised. The period 1770-1790 saw great advances in the study of the lymphatic system, largely under the impetus of Mascagni, who alone discovered about fifty percent of the lymphatic vessels now known. In Britain Hewson, Cruikshank, and Sheldon were also active in the field of lymphatics and made valuable contributions to the subject.

The introduction of colour plates brought enormous benefit to anatomical illustration, especially in certain branches of medicine. It is a fortunate coincidence that around the time that colour illustration was becoming widespread, great progress was being made in dermatology and pathology. In a work that laid the foundation of modern dermatology, Willan chose colour-printed stipple engraved plates to demonstrate various skin disorders in vivid detail, and in so doing produced beautiful illustrations of an unattractive subject [14]. Colour could not only highlight distinct parts of the body; it could also show changes in natural states brought about by morbid conditions. In their pathology textbooks Carswell [15], and Bright [16] used colour plates to great effect, and contributed greatly to knowledge of morbid anatomy.

Other changes in technology brought considerable advantages to anatomical illustration. The mechanization of printing in the nineteenth century, together with the invention and development of lithography, meant that texts and illustrations could be mass produced, and widely distributed through networks of publishers and booksellers. By the mid century lithography had all but replaced intaglio processes as the principal method used for anatomical illustration. With the introduction of chromolithography in the 1830s, anatomical illustration reached perhaps its highest level in the multi-volume atlas of Bourgery [17].

Twentieth-century printing techniques, particularly photographic processes, along with the more advanced computer imaging, continued to bring scientific advances in the knowledge of anatomy. Nevertheless, the period covered by Anatomia, the sixteenth to the nineteenth centuries, continues to be of considerable interest as a record of the tremendous progress in both the understanding of, and the depiction of human anatomy. Despite their inaccuracies these works will remain as highpoints in both anatomy and art, and will continue to be studied and admired as testaments to their time and their creators.