The effect of age on mitochondrial ultrastructure.

The ultrastructure of perfused livers and of mitochondrial fractions from 6-month-old and 30-month-old C57/BL mice were studied. In old mice the liver cell mitochondria were enlarged and rounded with a light 'foamy', vacuolated matrix, short cristae and a loss of dense granules. Quantitative studies showed a 60% increase in the mean size and an increased proportion of larger mitochondria in intact 30-month-old perfused livers. Endothelial and Kupffer cell mitochondria were smaller than those of the parenchymal cells. Mitochondria in pellets prepared from 6- and 30-month-old livers were rounded and condensed, although there were a few larger and 'foamy' mitochondria in the preparations from old mice. Up to 47% of large mitochondria in the old livers were lost during cell fractionation.     

The ultrastructure of the neonatal pig colon.

The neonatal pig colon has several unique structural and developmental features. At birth it has a variable population of epithelial cells which in their arrangement on villus-like protrusions and in their capability for protein uptake into large preformed supranuclear vacuoles closely resemble neonatal ileal cells. Such villus-like protrusions and vacuolated cells are not present in the 2-day-old piglet. On the first day after birth absorptive epithelial cells which lack supranuclear vacuoles transiently accumulate a large number of lipid droplets, each separated from the cytoplasm only by a proteolipid interface. None of the much smaller lipid droplets bounded by a unit membrane of the smooth endoplasmic reticulum and characteristic of normal small intestinal fat uptake were ever seen in these cells. Very few of the large lipid drops remain on the second day after birth. This initial capacity of the colon for protein and lipid uptake never reappears. The pattern of colonic amino acid transport also changes markedly in the first four days of independent life and this may be correlated with the observation that the absorptive cells at birth have microvilli which are twice the length of those on similar cells at and after two days old. These morphological results are discussed in terms of implied functional changes in the neonatal period.     

The chorion ultrastructure of ova of Lophius spp.

The chorion surface ultrastructure of unfertilized eggs of black anglerfish Lophius budegassa and white anglerfish Lophius piscatorius was examined by scanning electron microscopy. Species‐specific differences were observed.     

The ultrastructure of the cellulolytic bacterium Cellvibrio fulvus.

Thin sections of the cellulolytic bacterium Cellvibrio fulvus were investigated before and after treatment with polymyxin B and Triton X-100. The Gram-negative vibrio appeared to have no separate stained g2 layer between the L and C membranes. Cells lysed after treatment with polymyxin or swelled in the presence of 5% sucrose. Blebs were formed from the L membrane, and the inner structure of the cells changed. Triton X-100 lysed cells even in the presence of 20% sucrose. The flagellum disappeared before lysis; one of the membranes was dissolved; and no organized inner structure could be seen.     

The influence of fetal circulation on liver cell ultrastructure.

This study shows that autolytic changes in liver tissue from mini-pig fetuses are less extensive if, after removal of the uterus, the fetal circulation is left anatomically intact until excision and fixation. It must be concluded that, if it is not possible to remove and fix fetal material immediately, the fetus should be kept in the intact amniotic cavity with an intact umbilical cord.