In this study carried out on the development of arteriovenous anastomoses (AVAs) in Rattus norvegicus species, the fetus was followed up 10 days after post coitum (pc). The sections obtained from the fetuses of 10-20-day rats were subjected to the usual processes for examination under the light microscope. Various staining processes were applied on the preparations and the simple and glomus types of AVAs determined in the mesenchyme of fetuses observed to birth every day. The regions with AVAs were then photographed by photomicroscopy and evaluated. From the 10-day embryo to birth, an increase in the smooth muscles in the wall structure of simple anastomoses was observed. It was however very difficult to follow up this increase in glomus anastomoses because the wall structure is more complicated. Their morphology was examined and compared with that in literature.