HISTOLOGY, HISTOCHEMISTRY AND ULTRASTRUCTURE OF HEART, LIVER AND PANCREAS IN PIGS (Sus scrofa domesticus)
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Date
2018-09
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KARNATAKA VETERINARY ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR
Abstract
The histology, histochemistry and ultrastructure of heart, liver and pancreas of
pigs was studied. Epicardium was composed of mesothelium which was simple
squamous epithelium resting on basement membrane, myocardium predominated with
cardiac muscle fibres along with connective tissue and Purkinje fibres while endocardium
was lined by endothelium beneath which there was subendothelial tissue.
Histochemically myocardium showed least presence of neutral and acidic
mucopolysaccharide, while epithelium and endothelium gave intense positive reaction.
The coronary artery was made of three layers namely, tunica intima, tunica media and
tunica adventitia of which tunica media was thicker composed of smooth muscle fibres
interlaced with reticular fibres while tunica adventitia composed of loose connective
tissue rich in elastic fibres. The moderator band was categorised into regions with the
presence of cardiomyocytes and Purkinje fibres while endothelium acted as a capsule.
Histologically valves had lamina fibrosa, lamina spongiosa and lamina atrialis/
ventricularis composed predominantly with collagen fibres, histiocytes and elastic fibres
respectively. The papillary muscle and chordae tendinae junction was clearly demarcated
and distinguished with abundant number of Purkinje fibres. Histochemically, various
intensities of reactions of acid mucopolysaccharides and glycosaminoglycans in different
regions of all the tissues were observed. The liver had capsule which entered the
parenchyma and divided into different hexagonal shaped hepatic lobules which had
central vein in the centre and radiating hepatic lamina composed of hepatocyes bordering
sinusoids. Sinusoids had space of Disse lined with endothelium, Kupffer cells and Ito
cells. Bile canaliculi between two hepatocytes were evident both histologically and
ultrastructurally. Hepatocytes reacted differently to polysaccharides while capsule and
interlobular septa showed intense positive reaction. Reticular fibres which was fine,
branching and anastomosing framed the hepatocytes and sinusoids. The pancreas was
tubuloacinar type of gland covered by a thin capsule, made up of predominantly collagen
fibres. Each acinus showed a single row of pyramidal epithelial cells resting on the
basement membrane. The cytoplasm of the acinar cells showed two distinct zones i.e.,
basal and apical zone which was basophilic and acidophilic with numerous zymogen
granules. Three types of acinar cells were noted in pancreas i.e. active, resting and
exhausted type. The duct system of the pancreas consisted of larger interlobular, medium
sized intralobular and small intercalated ducts. The endocrine tissue appeared as lightly
stained areas between the darkly stained acini of different shapes and sizes. The alpha
cells had pale cytoplasm, ovoid nucleus occupied the peripheral region in the islet but
beta cells with dark cytoplasm and spherical nucleus were in the centre. Delta cells were
distributed mainly peripherally in the periphery of islets and they were irregular in shape
with cytoplasmic process.
Key words: Pig, Heart, Liver, Pancreas, Valves, Myocardium, Hepatocytes, Islets.