Studies on the liver of Xenopus laevis. II. The ultrastructure of the peritoneal cover and the perihepatic layer.

The peritoneal cover and the subcapsular region of the liver of Xenopus laevis were examined with electron microscopy. In the subcapsular region a prominent perihepatic layer two to ten cells wide was found. This perihepatic layer is mainly composed of granulocytopoietic tissue. Other cell types found in the perihepatic layer were lymphocytes, pigment cells and fat storing cells. The presence of a perihepatic granulocytopoietic layer in the liver of Xenopus laevis is in contrast to current opinion that such a layer is a characteristic typical of urodeles. The phylogenetic significance of such a layer in anurans and the developmental processes of the individual cell types of the perihepatic layer are discussed. Furthermore the possible participation of the perihepatic layer in the immune response is considered.