[Histologic study of the teleost liver. I. The structure of the liver parenchyma]

The liver parenchyma of the teleosts investigated in this study does not show a true lobular pattern. The finer arrangement of the hepatocytes corresponds to the classical conception that the structure of the liver parenchyma is tubular. On the other hand the laminar structure of parenchyma (ELIAS), as it is often described in the more recent literature, must be regarded as a predominantly descriptive perspective. Remnants of a tubular structure also appear in the liver of the cyprinids investigated here, which have no real liver tubules owing to the special feature of the canalicular region (unicellular or "intracellular" bile canaliculi). Compared to the liver of higher vertebrates eight of the nine teleost species investigated here possess a liver poor in connective tissue. The liver of Haplochromis burtoni also lacks a continuous tissue layer beneath the peritoneal mesothelium. In contrast the liver of Tetraodon leiurus is characterized by an abundance of connective tissue. This phenomenon can be attributed to the high proportion of sinusoids in the parenchyma, which confers a structure similar to that of mammalian liver. The resulting loss of mechanical stability is obviously compensated for by the enlarged contribution of the connective tissue to the structure of the parenchyma.