[Development of the rectal fascia].

The development of the fascia recti was investigated by 300-600 microns thick sections through the pelves of 8-35-week-old human fetuses, of newborn children and adults. The pelves were impregnated with an epoxy resin and cut with a diamond wire-saw. We here report that the fascia recti develops as part of the adventitia recti. In 9-week-old fetuses the latter consists of condensed mesenchyme which in 18-20-week-old fetuses develops to a fibrous connective tissue surrounding the rectum. In newborn children adipose tissue starts spreading between the connective tissue lamellae of the adventitia recti and thereby separates them. The most external of these connective tissue lamellae is rather dense and can be regarded as fascia recti. In the adult we found it not always as strongly marked as in newborn children. The close developmental relations between the fascia recti and the tissue of the adventitia recti might be seen as cause for the temporary stop of tumor spread at the fascia recti.