A historical overview of the study and representation of uterine microvascular structures

The concept of anatomical modelling of the internal vascular structures of organs dates back to the Middle Ages by way of corrosion casting. The first to apply this classic injection technique in the reproductive arena was John Hunter (1754), who undertook to establish the independence of the maternal and fetal circulations in the placenta. The first detailed microscopic study of the endometrial vessels was undertaken a century later. Endometrial inoculation studies in the 1930s with coloured fluids such as India ink have provided the basis of our current understanding of the complex sequence of morphological vascular changes which occur in the endometrial tissue leading up to and during the process of menstruation. Classic injection techniques were limited in that they were often associated with artefacts due to injection-induced vessel breakages and variability in size of the suspended particles in the injection material. Following this, the smallest blood vessels were better demonstrated using Gomori's alkaline phosphate method. An adaptation of this method in the early 1960s demonstrated the uterine vasculature in a more detailed way than ever before. In the early 1970s, novel microradiography studies involved the injection of warmed radio-opaque medium into both arterial and venous microvasculature of the human uterus. Early 1980s investigators also utilized corrosion casting of uterine microvessels combined with scanning electron microscopy. The last 20 years have seen the dawn of the computer age, immunohistochemistry, advanced microscopy (laser scanning confocal and multiphoton emission), and stereological methods to obtain quantitative measurements of 3-dimensional endometrial vascular structures. This review article contains a historical overview of uterine microanatomical vascular visualisation from the early beginnings to the latest computerised techniques.