title: The morphology of the adrenal gland in the European bison (Bison bonasus).
abstract: BACKGROUND
  The anatomy of the adrenal glands has been widely studied in many species of domestic and wild mammals. However, there are no available literature reports describing the morphology and morphometry of the adrenal glands of the European bison (Bison bonasus).
  
  
  RESULTS
  The study was conducted on 97 European bison of both sexes. The growth of the adrenal glands corresponded to the growth of the whole body, with the largest increase in size occurring in the first 2 years of the animal's life, followed by a slower increase in size until the animal was 5-7 years old. There were no statistically significant differences between ipsilateral adrenal glands of males and females with respect to age. There was no statistically significant difference in weight between the left and the right adrenal gland. However, there was a difference in the length, width and thickness of the two glands. Reference intervals for adrenal gland size and weight were computed separately for two bison age groups (up to 2 years of age and older than two years). The adrenal gland consisted of a cortex and a medulla. The connective-tissue capsule contained two layers. It had a fibrous structure and abundant adipose tissue. The cortex was divided into three zones. The zona glomerulosa contained cells arranged in bundles and curves. Numerous apoptotic cells were observed among regular cells in the zona reticularis. There were vacuoles in the cells of both zona fasciculata and zona reticularis, which formed a foamy cytoplasm. The adrenal medulla was composed of large, dark cells with a highly basophilic cytoplasm in the superficial region and of smaller, lighter cells in deeper layers. Sinusoidal vessels were located in the central part of the medulla.
  
  
  CONCLUSIONS
  The left adrenal gland was significantly longer, narrower and thinner than the right one. There were no significant differences in the structure of the adrenal medulla and cortex of the European bison compared to other species of domestic and wild mammals. There was a thick layer of adipose cells at numerous locations in the adrenal capsule of the bison.
authors.affiliation: Department of Morphological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, 159 Nowoursynowska, 02-776, Warsaw, Poland. karolina.barszcz@onet.eu.
authors.forename: Karolina
authors.initials: K
authors.lastname: Barszcz
authors.affiliation: Department of Morphological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, 159 Nowoursynowska, 02-776, Warsaw, Poland.
authors.forename: Helena
authors.initials: H
authors.lastname: Przespolewska
authors.affiliation: Department of Morphological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, 159 Nowoursynowska, 02-776, Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Olbrych
authors.affiliation: Laboratory of Veterinary Epidemiology and Economics, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776, Warsaw, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Czopowicz
authors.affiliation: Department of Animal Physiology and Biostructure, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, Kozuchowska 1/3, 51-631, Wroclaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Klećkowska-Nawrot
authors.affiliation: Department of Animal Physiology and Biostructure, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, Kozuchowska 1/3, 51-631, Wroclaw, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Goździewska-Harłajczuk
authors.affiliation: Department of Morphological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, 159 Nowoursynowska, 02-776, Warsaw, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Kupczyńska
mesh_terms: D000273:Adipose Tissue / Q000166:cytology; D000311:Adrenal Glands / Q000033:anatomy & histology* / Q000166:cytology; D000818:Animals; D016164:Bison / Q000033:anatomy & histology*; D005260:Female; D008297:Male
keywords: Adrenal gland; European bison; Histology; Morphology