The aim of this study is to determine the anatomical features and histological structures as well as some histochemical aspects of the liver of three species of birds that differ in their nutrition, habitat and classification, by using light microscope. The birds were Larus canus, Agaporins fischeri and Numida meleagris. The results showed that the liver of the three species of birds was a dense, large and bilobed organ, it differed in size, color, lobes shape and presence of secondary lobes among the three species. The liver tissue of the three species consisted of hepatocytes which were radially arranged around the central veins interconnecting laminae of one to two cell thickness. The hepatocytes differed in size among the three species. Lumen of sinusoids contained mainly erythrocytes, macrophages and lining by the Kupffer cells. Histochemically, the hepatic cells in the three species of birds were weakly positive to periodic acid Schiff and alcian blue reactions, while they were negative to bromophenol blue reaction and they were moderately positive to Sudan black B reaction.

Heavy material pollution is one of the most critical threats to fish stocks around the world. Lead is one of the essential heavy elements that directly or indirectly affect fish. The purpose of this study is to investigate the effects of sublethal concentration of lead chloride PbCl2 on the brain of Gambusia affinis. For this purpose, 90 fish were used, which were divided into nine groups, each group containing ten fish. They divided into a control group, the acute treatment groups included four groups exposed to concentrations of 20 and 25 mg/L of PbCl2 for 24 and 96 hours, respectively. At the same time, the chronic treatment included four groups exposed to concentrations of 5 and 10 mg/L of PbCl2 for 15 and 30 days, respectively. The results showed that there were histological lesions that appeared in all the treated fish compared to the control group. These lesions appeared in different degrees of concentration and duration of use. Among the most prominent of these tissue changes that were repeated in the treatments were degeneration, vacuolar degeneration, necrosis, hemorrhage, congestion and oedema as well as disintegration between different brain tissues. The study concluded that lead chloride has a very harmful effect on brain tissues and that chronic exposure leads to irreversible histological lesions.

Background The present study is designed to identify the morphological description of the digestive tract in two species of different birds; these birds were Taeniopygia guttata (zebra finch) which is granivorous and Sturnus vulgaris (Starling) which is omnivorous. Results The results showed that the digestive canal of both birds was similar in the essential structure. It begins with the oropharyngeal cavity, which starts with the beak. The beak appeared different in the outer shape, which depends on the feeding. The mouth palate in both birds contains slit localized in the hard palate. This slit represents as beak nostril. The tongue appeared at the bottom of the oropharyngeal cavity. The esophagus appeared as a muscular tube containing the crop, which is divided into two parts the cervical part and the thoracic region, while the stomach was composed of two clear parts in both birds. The first one was a conical shape called proventriculus. The second was a spherical shape called the gizzard, and they are separated by a transitional zone called the isthmus, which was more apparent in the zebra finch, while the small intestine developed mostly in both birds. It is divided into three parts, which were the duodenum, jejunum, and ileum, as well as the large intestine, which appeared as tube shape, which is the rectum. There was a pair of caecum located in the contact area of the ileum and rectum. The digestive canal ends with the cloaca in both birds. Conclusion These results indicate that there are differences in the anatomical structure of the gastrointestinal tract organs between the two birds to be compatible with the quality and method of obtaining food.

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