Morpho-histological Studies of the Interrenal Body, Trunk Kidney and the Urinary Bladder of Indian Gar-fish Xenentodon cancila (Ham.

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1 Okajimas Fol. anat. jap., 48: , 1971 Morpho-histological Studies of the Interrenal Body, Trunk Kidney and the Urinary Bladder of Indian Gar-fish Xenentodon cancila (Ham.) By 0. P. Gupta and R. K. Shrivastava Department of Zoology University of Saugar SAGAR (M. P.) INDIA Received for publication, January 7, 1971 Introduction The kidneys of the teleosts are different from other vertebrates in a number of features. The aglomerular kidney is only found among the teleosts, for example in Lophius and Hippocampus (Edwards, 1928, '35). In other teleosts the structure of the nephrons shows considerable variations as reported by Graffin (1937), Nash (1937), Rangarajan. (1951) in Aplocheilus melastigma, Tampi (1959) and Nadkarni (1916) in C. mrigala. Material and Methods The present study was made by transverse sections of 35 mm. fish as well as variously stained sections of the adult kidney. Apart from the usual Haematoxylin and eosin stain, Weisel's (1902) Toluidene blue and Safranin stain, and Lillie's (1951) Allochrome stains were also used. The fresh preparations were made by keeping the adult kidney in 50% Hydrochloric acid for 24 to 40 hours and then pieces were examined in Creosote after washing thoroughly with water. The kidney tubules and the glomerulii become clearly visible by this procedure. Observations and Discussion The kidneys which are mesonephric and the main excretory organs in Xenentodon, can be divided into two parts. A. Interrenal Body (Cephalic kidney, Lipoid body or Anterior kidney) 205

2 P. Gupta and R. K. Shrivastava The anterior kidney (INT. R. Fig. 1) has been variously designated as the cephalic kindey, interrenal body, lipoid body and also as the anterior interrenal body. The name interrenal body was adopted by Balfour in 1878 and has since been commonly accepted. Fig. 1. Dissection of Xenentodon from ventral side showing the excretory organs, interrenal body and corpuscles of Stannius. Abbreviations : CORP. ST. Corpuscle of Stannius G. OP. Genital opening INT. R. Interrenal LAD. TR. KID. Ladder-like appearance of trunk kidney TES. Testis TR'. KID. Trunk kidney URE. Ureter URI. BL. Urinary bladder UR. OP. Urinary opening

3 Morpho-histological Studies of the interrenal body 207 In this work it is designated as the interrenal body. It corresponds to the cortical portion of the mammalian adrenal. The interrenal body lies as a compact mass, a short distance behind the septum transversum. The pronephric duct (P. NEP. D. Fig. 2) runs through or by the side of it. Although renal in origin it appears to be entirely endocrine in adult. The interrenal bodies are richly supplied by the arterial branches, one from the posterior epibranchial artery and the other from the dorsel aorta. In addition, the branch from the dorsal has an ampulla before its entry into the substance of the interrenal body (Gupta, 1969 a). Each interrenal body is an elongated mas about twice the size of a wheat grain. There is a thin outer capsule of connective tissue. Internally the cortical cells are grouped in masses mainly round the veins and the rest looks like pseudolymphoid tissue (PSEUDO. T. Fig. 2). The cells are basophilic with large nuclei. The pigment cells (P. Fig. 2) are seen here and there not only in the interrenal body but also in the trunk kidney. A few of, the apparent pigment cells take a greenish tinge by the Weisel's (1902) stain showing thereby the probable presence of the some chromaffin material. The chromaffin cells take deep stain and have vacuolated cytoplasm in other fishes (Baecker, 1928). The term chromaffin tissue was used by Kohn in 1859 and since then it is considered as representing the medullary portion of mammalian adrenal. B. Trunk Kidney It is the main excretory organ. It lies (TR. KID. Fig. 1) just below the vertebral column and on either side of the dorsal aorta. It is attached to the vertebral column by connective tissue. It is light ochre in colour with black spots of pigment here and there. It extends from behind the interrenal body upto a few mm. behind the anal region. The anterior half of the kidney is a thin mass which gives a ladder-like appearance (LAD. TR. KID. Fig. 2) In the posterior half, the right and left kidneys are distinct. Each kidney is made up of a number of nephrons. Each nephron (NEP. Fig. 3) opens into the mesonephric duct. It is divided into two or three secondary branches and further into tertiary branches. The glomeruli are few. Each glomerulus is covered by a lining of flattered cells containing inside a mass of the afferent and efferent capillaries. The nephron or the uriniferous (UR. T. Fig. 4) tubule forms a Bowman's capsule (B. CAP. Fig. 4) round the glomerulus. Just after the Bowman's capsule, a distinct region, the neck (NE. Fig. 4) can be recognised in the nephron. Neck cells are cuboid in shape and strongly basophilic. They

4 P. Gupta and R. K. Shrivastava are of two types. Majority of them have large ovoid nuclei with clear nucleoplasm and few chromatin particles. In the second type of cells, the nucleus takes an intense blue stain. Part of the nucleus towards the internal lumen of the tubule forms a cap of dense material oh the remaining half, which has clear nucleoplasm with one nucleolus. After the neck the tubule is lined by large cuboid cells and a typical brush border. From the study of the transverse sections, three parts can be made out : i) Distal neck segment ii) Middle brush border segment iii) Proximal segment The exact extent of each segment as well as the size of nephron could not be determined. A photograph of a single nephron (NEP. Fig. 3) is provided but the size varies in the different parts of the kidney. In any case, brush border appears to be present practically in the whole of the nephron. The mesonephric ducts lie in the median line close together. Anteriorly they separate and pass through or by the side of the interrenal body (anterior or cephalic kidney) of their own side. Posteriorly the two mesonephric ducts open separately into the urinary bladder. The urinary bladder opens by a separate opening behind the genital duct both in the male and the female. The urinary and the genital openings are separate. The mesonephric duct is made up of a single layered epithelium covered by a thin coat of connective tissue. Some circular muscle fibres are adso seen below the connective tissue covering. The urinary bladder (URI. BL. Figs. 1 and 5) is a clubshaped structure. Anteriorly it is broader but tapers posteriorly. The ureters (mesonephric ducts) open separately into it at about its middle. Its wall shows the following features : i) Internal epithelium (EP. F. Fig. 5) is single layered with many cuboid and polygonal cells. It shows a number of longitudinal folds. ii) Subepithelium (S. EP. Fig. 5) is made up of connective tissue with irregular muscle fibres. iii) Muscle coat has thick layer of circular muscles (C. M. Fig. 5). iv) The outermost serosa (SE. Fig. 5) consists of a thin membran.e of connective tissue and minute blood capillaries.

5 Morpho-histological Studies of the Interrenal body 209 Acknowledgement Our sincere thanks are due to Dr. H. N. Bhargava, Head of the Department of Zoology for providing the necessary facilities for this work. Summary The kidneys in Xenentodon are mesonephric. The anterior portion of each kidney has become modified into the interrenal body. Although renal in origin the interrenal bodies appear to function as the endocrine organs in the adult. In the nephron three parts that is distal neck, middle brush border and the proximal segments can be made out. The mesonephric duct lies in the median line. Anteriorly they separate and pass through or by the side of the interrenal body. Posteriorly the mesonephric ducts open separately into the urinary bladder, which opens to the outside by an independent urinary aperture. Literature Cited Balfour, F. M On the origin and histology of the Urinogenital organs of vertibrates. Jour. Anat. Pary On the nature of excretory organs, in adult teleosts and ganoids usually regarded as the head kidney or pronephros. Quart. Jour. Micros. Sci. XXX : Baecker, R Ueber dier Nebenniren der Teleostieren. Zeitschr. f. Mikr. Anat. Forsch. Vol. 15, P Edwards, J. G Studies on aglomerular & glomerular kidneys. Amm. J. Anat. Vol. 42, p The epithelium of renal tubule in bony fishes. Anat. Rec., Vol. 63, p Graffin, A. L The structure of the nephron in fishes. Anat. Rec. Vol. 68, p Gupta, 0. P a. Blood Vascular System of Xenentodon (Ham.) Morph. Jb. Leipzig, Bd. 114, Heft 2, Seiten Lillie, R. D American J. Clin. Path. Vol. 21, pages Nadkarni, V. B Studies on the pronephros of Cirrhina mrigala. Acta. Zool. XLVII Nash, J The number & size of glomeruli in the kidneys of fishes, with observations on the morphology of the renal tuble of Fishes. Amm. J. Anat. Vol. 47, p Rangarajan, K The prenephros of Aplocheilus melastigma (McClelland). Current Sci. 20. p Rastogi, R. K Morphological and Histological study of the Urinogenital organs of Mystus teengara. Zoologischer Anz. CLXXVIII : Tampi, P. R. S On the renal unit in some common teleosts. Proc. Indian Acad. Sci. 50 B: figs. Wiese], Anatomische Hefte: Abteilung 1. Vol. 19 : p. 481.

6 P. Gupta and R. K. Shrivastava Explanation to Plate I. Fig. 2. Xenentodon adult : T. S. of interrenal body. x 270 Fig. 3. Xenentodon adult A nephron preparation from the kidney. x :76 Fig. 4. Xenentodon adult : T. S. of kidney. x 120 Fig. 5. Xenentodon adult : T. S. of urinary bladder. x 60 Abbreviations : C. M. Circular muscles CON. T. Connective tissue EP. F. Epithelial folds LU. Lumen N. D. Nephron duct NEP. Nephron N. NEP. Neck of nephron P. Pigment P. NEP. D. Pronephric duct PSEUDO. T. Pseudolymphoid tissue SE. Serosa S. EP. Subepithelium SEC. NEP. Secondary nephron UR. T. Uriniferous tubule

7 211 Plate I O.P.Gupta and R.K.Shrivastava