Ultrastructure of in situ perfusion-fixed avian liver, with special reference to structure of the sinusoids

Structure and age-dependent growth of the chicken liver together with liver fat quantification: A comparison between a dual-purpose and a broiler chicken line

Rearing dual-purpose chickens is a practicable approach to avoid culling one-day-old male layer chicks. The present study examined the impact of a conventional fattening diet on the liver of a novel dual-purpose chicken line (Lohmann Dual, LD) in comparison to a broiler (Ross 308) chicken line. Age-related changes of structure and lipid content of the liver were assessed. One hundred twenty and newly hatched chicks (LD = 66, Ross = 54) were kept under the same husbandry conditions and fed a commercial diet for 5 weeks for Ross and 9 weeks for LD. Six birds of each line were examined weekly. Their body weight (BW) and liver mass were recorded. Microscopic structure and ultrastructure of the liver were investigated and the liver lipid content was measured using a pre-validated method. During the study period, liver mass increased with age, while normalized liver mass decreased. Furthermore, liver mass of Ross birds was greater than that of LD birds of the same BW. Overall, no significant differences were observed in the hepatic structure or ultrastructure between the two chicken lines. The hepatic lymphatic aggregations were without fibrous capsules and their number and area increased throughout the first week, then the values began to fluctuate with age in both chicken lines. The changes in the liver lipid content of the two chicken lines were within the normal physiological range over the term of the study. The liver lipid content correlated negatively with age and body weight in both lines. It was the highest on the first day then decreased until day 7 and thereafter did not change in both chicken lines. However, given the same body weight, the Ross chickens had a 9% greater liver lipid content than LD chickens. It is concluded that there is no apparent adverse effect of a high-energy diet on the liver of LD chickens.

Structure and age-dependent development of the turkey liver: a comparative study of a highly selected meat-type and a wild-type turkey line

In this study the macroscopic and microscopic structure of the liver of a fast growing, meat-type turkey line (British United turkeys BUT Big 6, n=25) and a wild-type turkey line (Wild Canadian turkey, n=48) were compared at the age of 4, 8, 12, 16, and 20 wk. Because the growth plates of long bones were still detectable in the 20-week-old wild-type turkeys, indicating immaturity, a group of 8 wild-type turkeys at the age of 24 wk was included in the original scope of the study. Over the term of the study, the body and liver weights of birds from the meat-type turkey line increased at a faster rate than those of the wild-type turkey line. However, the relative liver weight of the meat-type turkeys declined (from 2.7 to 0.9%) to a greater extent than that of the wild-type turkeys (from 2.8 to 1.9%), suggesting a mismatch in development between muscle weights and liver weights of the meat-type turkeys. Signs of high levels of fat storage in the liver were detected in both lines but were greater in the wild-type turkey line, suggesting a better feed conversion by the extreme-genotype birds i.e., meat-type birds. For the first time, this study presents morphologic data on the structure and arrangement of the lymphatic tissue within the healthy turkey liver, describing two different types of lymphatic aggregations within the liver parenchyma, i.e., aggregations with and without fibrous capsules. Despite differences during development, both adult meat-type and adult wild-type turkeys had similar numbers of lymphatic aggregations.

Susceptibility of chicken Kupffer cells to Chinese virulent infectious bursal disease virus

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). Although the effects of IBDV on bursa of Fabricius in chickens have been well reported, the impacts of IBDV on liver after IBDV infection are still unclear. In the present study, specific pathogen free (SPF) chickens were experimentally inoculated with IBDV Chinese virulent strain BC6/85, and the cells in liver and bursa were examined by immunohistochemistry and transmission electron microscopy (TEM). The congestion of liver tissue and fatty degeneration of hepatocytes were characteristics of microscopical changes in chicken liver at 3 days post infection (d.p.i.), whereas there were follicular lymphoid necrosis, apoptosis, depletion, as well as edema and congestion in bursa. In addition, the number of IBDV-positive cells peaked at 4 d.p.i. in bursa and at 3 d.p.i. in liver, respectively. With respect to ultrastructural pathological changes of hepatocytes, mitochondria swelled and nucleus deformed into an irregular shape or its chromatin peripherally condensed which indicated that the hepatocyte was at the early stage of apoptosis, and the electron-lucent lipid droplets in a variety of sizes were observed within cytoplasm. Kupffer cells became "swollen-like" and the electron-density of their cytoplasm was lower than that of cells in uninfected group. Liver glycogen deposits significantly declined from 2 to 5 d.p.i. and recovered strongly at 6 d.p.i. More importantly, KLU01 (macrophage marker) positive (KUL01(+)) cells were infiltrated in bursa and liver in IBDV-exposed chickens by immunoperoxidase staining. To demonstrate the correlation between IBDV and macrophages in bursa and liver, we further investigated the colocalization of viral antigens and macrophages by double immunofluorescence labeling. At 4 d.p.i., the percentage of double positive cells (IBDV positive and KUL01(+) cells) accounted for 26.5 percent of the total IBDV positive cells or 57 percent of the total KUL01(+) cells in bursa. In comparison, the percentage of double positive cells in liver constituted 97 percent of the total IBDV positive cells or 99 percent of the total KUL01(+) cells. These results suggest that IBDV was susceptible to KUL01(+) cells in liver (mainly Kupffer cells) and replicated in the KUL01(+) cells. By comparison with the influence of IBDV on bursa, our findings were the first to elucidate the pathological changes in liver after IBDV infection on a microscopical and ultrastructural scale, and, especially, to gain the initial insight into the susceptibility of Kupffer cells to IBDV.

Exoerythrocytic development of Plasmodium gallinaceum in the White Leghorn chicken

Plasmodium gallinaceum typically causes sub-clinical disease with low mortality in its primary host, the Indian jungle fowl Gallus sonnerati. Domestic chickens of European origin, however, are highly susceptible to this avian malaria parasite. Here we describe the development of P. gallinaceum in young White Leghorn chicks with emphasis on the primary exoerythrocytic phase of the infection. Using various regimens for infection, we found that P. gallinaceum induced a transient primary exoerythrocytic infection followed by a fulminant lethal erythrocytic phase. Prerequisite for the appearance of secondary exoerythrocytic stages was the development of a certain level of parasitaemia. Once established, secondary exoerythrocytic stages could be propagated from bird to bird for several generations without causing fatalities. Infected brains contained large secondary exoerythrocytic stages in capillary endothelia, while in the liver primary and secondary erythrocytic stages developed primarily in Kupffer cells and remained smaller. At later stages, livers exhibited focal hepatocyte necrosis, Kupffer cell hyperplasia, stellate cell proliferation, inflammatory cell infiltration and granuloma formation. Because P. gallinaceum selectively infected Kupffer cells in the liver and caused a histopathology strikingly similar to mammalian species, this avian Plasmodium species represents an evolutionarily closely related model for studies on the hepatic phase of mammalian malaria.

Three-Dimensional Surface Structure of Macrophages in Fetal and Adult Mouse Liver: An Immunohistochemical Light Microscopic Study

Using 100-microm-thick paraffin sections stained by F4/80 antibody, the three-dimensional surface morphology of macrophages in fetal and adult livers was examined by conventional light microscope equipped with a computer-controlled z-axis stepping motor. Hematopoietic macrophages in fetal livers were located in the center of erythroid cell clusters, forming cell sockets which consisted of two different kinds of projections. The primary cytoplasmic processes were membranous projections and the secondary processes were finger-like projections extending from the primary processes. Erythroids in the cell sockets were linearly arranged on the macrophage surface. Adult sinusoidal macrophages possessed a few pseudopod-like processes, ridge-like profiles and numerous ruffle or spike-like processes, and cell contact with neighboring macrophages could be recognized. Compared to confocal laser scanning microscopy and scanning electron microscopy, this study provided information about cell surface structures at reasonably low cost, although the resolution was limited in z axis due to the stepping interval.