Okajimas Folia Anat. Jpn., 63(6): 393-406, March 1987

Fine Structural Changes in the Three-Dimensional Structure of the Rat Juxtaglomerular Apparatus in Response to Water Deprivation

By

Sumie KIDOKORO

Department of Anatomy, Yokohama City University School of Medicine, Kanazawaku, Yokohama, 236 Japan

-Received for Publication, December 26, 1986-

Key Words: juxtaglomerular apparatus, reconstruction, ultrastructure, water deprivation, rat

Summary: Morphological changes in the juxtaglomerular apparatus (JGA) after water de- privation, especially those in the spatial relationships among the structural components of the JGA were investigated by electron microscopy of serial sections and the three-dimen- sional reconstruction. The most remarkable changes were observed after 1-day-water depriva- tion, i.e. the secretory granule-containing cell layer in the was markedly increased in extent, and the ratio of contact area between the Goormaghtigh cells (GoCs) and the of the distal tubule to the whole surface of the GoC field was signifi- cantly reduced. A possible role of the GoCs in function of the JGA was discussed.

The morphology of the juxtaglomerular a functional system for tubulo-glomerular apparatus (JGA) has been intensively studied feedback mechanism. It has been described by various approaches, including three- that the JGCs are also found in the efferent dimensional study using reconstruction arteriole as well as in the extraglomerular of serial sections (Barajas & Latta, '63; mesangial cells in some occasions. It is Faarup, '65; Barajas, '70; Christensen et al., generally recognized that several factors are '75; Christensen & Boll , '78; Gorgas, '78; involved in the control mechanism for Christensen et al., '79; Spanidis, '82), freeze- release: Changes in , fracture replicas (Pricam et al., '74; Boll et sodium balance in body fluid as well as in al., '75; Forssmann & Taugner, '77; Taugner blood plasma, nerve stimulation, Immoral et al., '78), immunocytochemistry (Edelman agents including adrenaline, noradrenaline, & Hartroft, '61; Sutherland, '70; Taugner II, antidiuretic hormone and et al., '79; Phat et al., '81; Taugner et al., others [see reviews of Keeton & Cambell '81; Fraggiana et al ., '82) as well as conven- ('84), Wright ('84), and Briggs '('85)]. A tional thin-section electron microscopy. number of morphological and physiological These studies have established that the evidences for participation of individual JGA consists of the macula densa of the components of the JGA in the feedback distal renal tubule, the juxtaglomerular cells mechanism have been provided in previous (JGCs) in the media of the afferent arteriole studies. And, it is presumed that the GoCs and the Goormaghtigh cells (GoCs) to form must play an important role in controlling

Send offprint request to: Dr. Sumie Kidokoro, Department of Anatomy, Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa, Yokohama, 236 Japan

393 394 S. Kidokoro

the feedback mechanism as a functional and embeded in an Epon-Araldite mixture. center, because of their central position in For morphometric analysis of extent of the the JGA and coupling with gap junctions JGC layer in the afferent arteriole, semithick to other cellular compartments (Pricam sections (0.5 pm in thickness) were cut on a et al., '74; Boll et al., '75; Forssmann et al., Porter-Blum MT-1 ultramicrotome, mounted '77; Taugner et al ., '78; Spanidis et al., '82). on slide glasses in order, and stained with However, few reports dealing with the toluidine blue. Serial sections were obtained three-dimensional analysis of morphological from 40 glomeruli only in the subcapsular changes in the JGA under experimental regions of the in each group, conditions have been presented . The present because the morphology of the JGA is study was carried out to observe changes known to vary depending on its location in the spatial relationship among the struc- in the (Faarup, '65). Photomicro- tural components of the JGA after water graphs of these sections were taken at deprivation, because dehydration is known magnification of X 1,000. Extent of the JGC to cause elevation of plasma renin activity layer was calculated by the distance between (PRA) (Lucke et al., '80; Zucker et al., '82), the vascular pole and the distal end of JGC and this may accompany morphological layer along the central axis of the afferent changes in the JGA. arterioles reconstructed, because even when the number of JGCs was markedly dimin- Materials and Methods ished they are always found in the arteriolar wall at the vascular pole. To examine the Male Wistar rats ranging from 202 to 287 extent of the direct contact areas between g in body weight were fed with standard the GoC field and adjacent structural com- rat food pellets. They were divided into 4 ponents, reconstruction models were made groups of animals deprived water for 1, 2, 4 as follows: Electron micrographs of semi- and 7 days. Each group consists of 10 rats, serial sections obtained from every 10 thin and those treated without any experimental sections were taken at X 2,500 of the initial procedures were examined as control. Prior magnification, and printed to become to experimentation, blood pressure in X 7,500 in the final magnification. They individual animals was measured by the were traced on hard board of polyvinyl- tail-cuff method. Under pentobarbital anes- chloride, from which individual cellular thesia, the blood was collected from the compartments of the JGA (afferent arte- inferior vena cava of 5 animals in each group riole, distal renal tubule, GoC field and a to measure the plasma renin activity (PRA) part of closely apposed to the by radioimmunoassay method (Fyhrquist vascular pole) were cut out and recon- et al., '76). In the other animals, the renal structed as shown in Figure 1. The contact tissue was fixed by perfusion with 2% areas were calculated using an Image Analyz- glutaraldehyde in 1M phosphate buffer ing System of the Model G/A Series (Muto following the method of Forssman et al. Kogyo Co. Ltd., Tokyo, Japan). ('77). The tissue blocks minced into 2x 1 x 2.5 mm were further fixed in the same Results fixative for 2 h, washed in buffer, and post- fixed in 0s04 in buffer for 45 min. They 1) Body weight and food intake: Water were then dehydrated with an ethanol deprivation caused a significant decrease in series, passed through propylene oxide, body weight and food intake (Table 1). JG Apparatus after Water Deprivation 395

Fig. 1. A model representing the three-dimensional structure of the juxtaglomerular apparatus (JGA) reconstructed from serial sections. A; afferent arteriole, D; distal renal tubule, E; , GoC; Goormaghtigh cell (GoC) field (striped), SG; juxtaglomerular cell (JGC) area (dotted).

Table 1. Alterations in body weight and food intake during water deprivation

* The means of total volume of food taken by each animal during individual experimental periods.

Decrease in average body weight was about after 2-day-dehydration, about 45% after 10% of the initial one after 1-day-water 4-day-dehydration, and about 36% after deprivation, about 15% after 2-day-dehydra- 7-day-dehydration, respectively. tion, about 20% after 4-day-dehydration, 2) Plasma renin activity (PRA): Average and more than 35% after 7-day-dehydration, values of PRA in individual cases were 15.25 respectively. In Table 1, food intake was ngAl/ml/h in control, 51.25 ngAl/ml/h indicated by the means of the total volume after 1-day-dehydration, 80 ngAl/ml/h after of food taken by each animal through 2-day-dehydration, and 112.5 ngAl/ml/h individual experimentations. It is obvious after 4-day-dehydration, respectively (Fig. that food intake per day decreased remark- 2). PRA after 7-day-water deprivation ably as the experimental period is prolonged. was not calculated, because body weight After one-day-dehydration, food intake was decreased so markedly that enough volume diminished to be 51.6% of control. In other of blood for radioimmunoassay was not experimental groups, it was about 53% obtained. However, PRA tended to rise 3 96 S. Kidokoro

Fig. 2. Changes in blood pressure (BP) and plasma renin activity (PRA) during experiments. continuously throughout the experimental period and the value after 4-day-dehydration was about 7.4 times higher than in control (Fig. 2). 3) Extent of the juxtaglomerular cell (JGC) layer: JGCs were found only in the media of the afferent arteriole, and not found either in the efferent arteriole or in the extra- and intra-glomerular mesangial regions, as far as examined in this study. Extent of the JGC layer was 35.2±11.5 in control and significantly increased to be 53.1±16.4 p.m after 1-day-waterdeprivation (p<0.01). In the other experimental groups, 2-, 4-, and 7-day-dehydration, the values were 46.0±12.9 ,um, 423 ±17.4 ,um, and duration (day, ) 343±13 pm, respectively(Fig. 3). Fig, 3. Changes in extent of the JGCs in 4) Blood pressure: Averageblood pressure the afferent arterioles after water de- was 111 mm/Hg in control, 117 mm/Hg privation for various periods. The after 1-day-dehydration, 115.5 mm/Hg after vertical scale (length, Mm) indicates the dehydration for 2 days, 112 mm/Hg after distance between the JGC at the vascular pole and the distal end of JGC layer of 4-day-dehydration, and 108 mm/Hg after the afferent arteriole. JG Apparatus after Water Deprivation 397

7-day-dehydration, respectively (Fig. 2). at the vascular pole. Shape and route of One-day-dehydration group showed the the distal renal tubule passing by the JGA highest value, which is comparable to the showed a great variety. Some distal tubules changes in extent of JGC layer of the passed by the JGA without any contact afferent arteriole. area to both the afferent and efferent arte- 5) Reconstruction: Three-dimensional re- rioles (Figs. 4-i and 5-i), and some others constructions from serial sections indicated had a direct contact with either of the a diversity of the spatial relationships afferent arteriole (Figs. 4-iv and 5-iii) or between the GoC field and the adjacent the efferent one (Fig.s 4-ii, 5-iv, 6-ii and structural components of the JGA. They 6-iii). Those with contact areas to both are summarized with simplified schematic arterioles were also observed (Figs. 4-iii, illustrations in Figures 4, 5 and 6. The an- 5-ii and 6-i). Thus, the GoC field appeared gles formed by the afferent or the efferent various in size and shape and generally to arterioles and the Bowman's capsule at the have a triangularly or quadrangularly py- vascular pole appeared various. Some arte- ramidal shape with the base toward the rioles passed through the capsule nearly macula densa. Among them, the GoC field perpendicularly, and others curved sharply after 1-day-dehydration appeared smaller

Fig. 4. Schematic illustrations indicating the spatial relationship of structural components of the JGA in control. GoC field (striped) is various in extent and shape, but it generally has a triangularly or quadrangularly pyramidal shape with the base toward the macula densa. In some occasions the distal renal tubule (D) has no contact area with eithex the afferent arteriole (A) or the efferent one (E), as shown in Fig. 4-i. Some distal tubules are seen to have the contact area (dotted) with either of the afferent arteriole (4-iv) or the efferent one (4-ii) and/or with both of the arterioles (4-iii). V; the vascular pole of the . 398 S. Kidokoro

) i i )

iv)

Fig. 5. Schematic drawings of the JGA after 1-day-dehydration. GoC field is appeared somewhat smaller in extent than the other cases, and has a triangularly pyramidal shape. Angles formed by the afferent and efferent arterioles at the vascular pole appear to be acute in many occasions. Shape and route of the distal tubule passing by the JGA are various (5-i, -ii, -iii, and -iv). in size than that in other groups, and the 7) Electron microscopy: In control, most angle formed by both arterioles at the of JGCs appeared swollen because of a num- vascular pole was seen to be acute in many ber of secretory granules in the cytoplasm. occasions (Fig. 5). These granules were spherical in shape and 6) Changes in direct contact areas of the had a dense homogeneous content (Fig. 7). GoC field with other structural components: Small bundles of the cytoplasmic filaments The ratios of the contact area of GoC field which terminate at the dense bodies in the with the other structural components of the cytoplasm or the hemidesmosomes at the JGA, such as the diastal renal tubule (G.D), plasma membrane were developed in inverse the afferent arteriole (GA), and the efferent proportion to the number of secretory arteriole (G' E), to the whole surface area granules. Moderately well-developed Golgi of GoC field (Go) were indicated in Table 2. apparatus was found at the perinuclear area. G-D/Go ratio was the minimal in value Small cisternae of the rough-surfaced endo- and significantly different from control. The plasmic reticulum were sparsely distributed means after 4-day-dehydration was also among secretory granules. A number of significantly different from that after 1-day- gap junctions were found between indi- dehydration (p<0,01). The other ratios were vidual JGCs as well as between the JGC changed in a measure depending on the and GoC (arrows in Fig. 8). The GoCs were experimental conditions, but no significant elliptical or spindle-like in shape and sepa- differences were detected among them. rated from each other with the basement

JG Apparatusafter WaterDeprivation 399

membrane, except for the sites of gap junc- tion. An ovoid or spindle-shaped nucleus occupied a central region of the cytoplasm, which contained poorly developed organel- les. The cytoplasmic processes appeared interdigitated. These cells filled the space among the macula densa and the afferent and efferent arterioles to form 2- to 4-cell- layers. After 1-day-dehydration, the JGSc which were found in a broad area of the afferent arteriole appeared flat and con- tained a small number of secretory granules with various densities. Deep infoldings of the surface plasmalemma accompanying the basement membrane were frequently ob- served in these cells, but omega-shaped invagination of the plasmalemma which suggests an exocytotic release of secretory granules was not found. These cells con- tained a well-developed Golgi apparatus

Fig. 6. The JGA after 4-day-dehydration. The GoC field is various in extent and shape from one to another. Contact areas between the distal tubule and the arterioles seem to be somewhat broader than those after 1-day-dehydration (6-i, and -ii).

Table 2. Ratios of contact area between Goormaghtigh cells (GoCs) and distal renal tubule, afferent arteriole, or efferent arteriole to the whole surface area of GoC field

Go; Whole surface area of Goormaghtigh cell field. G•D; Contact area between GoC field and the distal renal tubule. G•A; Contact area between GoC field and the afferent arteriole. GE; Contact area between GoC field and the efferent arteriole. t ; p<0.01 400 S. Kidokoro JG Apparatus after Water Deprivation 401

Fig. 8. The juxtaglomerular cells (JGCs) after 1-day-dehydration. Secretory granules (SG) decreased in number, and a well-developed Golgi apparatus is recognized in the perinuclear cytoplasm. Gap junctions are frequently detected between the cells (arrows). Inset; a part of gap-junctional area in higher magnification. X 16,000 (Inset) X 25,000 and slightly dilated, small cisternae of creased in number and their morphological the rough-surfaced endoplasmic reticulum. appearance varied from cell to cell. Some Cytoplasmic filament bundles were moder- cells appeared swollen with a number of ately well-developed. The GoCs had an mature secretory granules, and the others elongated cell shape with a number of became flat in shape and contained only a slender cytoplasmic processes and form a few granules with various densities. The multiply stacked cell layer. They contained latter provided numerous cytoplasmic fila- a number of mitochondria and a few small ment bundles and appeared quite similar cisternae of the rough-surfaced endoplasmic to the cells. The GoCs reticulum. Cytoplasmic filaments terminat- reduced in size and had a small number of ing in the hemidesmosomes at the plasma cytoplasmic processes (Fig. 10). No remark- membrane were frequently observed. The able changes in the ultrastructural features surface plasma membrane of the cytoplasmic of the epithelial cells of the macula densa processes as well as the cell body provided were detected through the present experi- a number of gap junctions (Fig. 9). As ments. dehydration is prolonged, the JGCs de-

Fig. 7. A survey of the JGA in control. Two to four layers of the GoCs (*) are localized within the space between the afferent arteriole (A) and the distal tubule (D) . They extend their multiply stacked cytoplasmic processes to contact with the efferent arteriole (not shown here, upper right out of the figure) (arrows). JGCs in the media of the afferent arteriole contain a number of secre- tory granules (SG) which have a spherical shape and a dense homogeneous content . G; glomerular capillary. X 8,000 402 S. Kidokoro

Fig. 9. Multiply stacked area of the Goormaghtigh cell processes between the afferent arteriole (A) and the distal renal tubule (D) in the JGA after 1-day-dehydration. A number of the cytoplasmic filament bundles which terminate in the hemidesmosomes at the plasma- lemma are observed (arrows). Gap junctions are frequently found between these processes but not detected between the process and the epithelial cell of the distal tubule X 19 nnn

Discussion the vascular smooth muscle cells of the As reported in previous studies (Lucke afferent arteriole into the JGCs may occur et al., '80; Zucker et al., '82), water depriva- dependent upon varying physiological and tion was associated with decrease in food pathological demands(Ishii & Fujimoto, '68; intake and body weight and caused a con- Peter et al., '74; Cain et al., '78; Fraggiana tinuous elevation of the plasma renin ac- et al., '82). A recent physiological study tivity (PRA). Three-dimensional reconstruc- (Biihrle et al., '86) revealed that renin- tions from serial sections revealed that mor- containing epithelioid cells (JGCs) and the phological changes in the juxtaglomerular vascular smooth muscle cells of the afferent apparatus (JGA) occured during dehydra- arteriole have a similar membrane potential tion. After 1-day-dehydration, the juxtaglo- as well as a similar reactivity to substances merular cells (JGCs) increased in number influencing renin secretion. Thus, there is resulting in a significant increase in extent no doubt that the initial increase in extent of the JGC layer of the afferent arteriole. of the JGC layer in the present study is due And, as dehydration is prolonged, the ex- to transformation of the vascular smooth tent of the JGC layer reduced gradually to muscle cells into the JGCs. These cells the average length of normal control. It is had a flat shape of the cell body, and con- known that a reversible transformation of tained a small number of secretory granules JG Apparatus after Water Deprivation 403

Fig. 10. The JGA after 4-day-dehydration. Moderate number of secretory granules with various densities (SG) are recognized in the JGCs. The Goormaghtigh cells (GoCs), which are small in size and have a few short processes, are intervened between the afferent arteriole (A) and the distal tilhilip a cnn with various sizes and densities and well- days, because an ultrastructural radioauto- developed Golgi apparatus in the cytoplasm. graphy (Desormeaux et al., '82) revealed Plasmalemmal invaginations, suggesting ex- that formation of renin-containing granules ocytotic release of secretory material as in the JGC does it take about 4 h, and described by Peter ('76) and/or Taugner turnover of these granules is considered et al. ('84), were not observed in these to be taken place relatively rapidly. Ac- cells. It is, therefore, considered that they cordingly, secretory activity of individual are in an active phase of secretory granule JGAs might be no longer synchronized formation rather than in the storage or later than 24 h after stimulation, but the releasing phases of the secretory cycle. initial changes occured within 24 h after Peter et al. ('74) described in their quanti- stimulation may reflect to some extent tative morphological analysis of the JGCs the secretory activity of the JGA. Con- after deoxycorticosterone treatment that sidering elevation of PRA and blood pres- the degree of granulation or degranulation sure, the present observation might be of the epithelioid cells (JGCs) does not, interpreted as follows: Secretory granules necessarily, reflect the secretory activity stored in the JGCs were released promptly of the JGA. This must be true when mor- in response to ionic inbalance of body fluid phometric evaluations were carried out caused by dehydration and subsequent for some period with intervals of a day or recovery of secretory granules occurred in 404 S. Kidokoro

greater extent of the agranular smooth his colleagues ('75, '78, '79) described in muscle cells in the wall of the afferent their light microscopic analyses that direct arterioles. And also, it may be speculated contact between the macula densa and that renal renin plays an important role the arterioles was not always present and in the initial step of rise of PRA and blood the contact area, even when existed, was pressure, and a prolonged water deprivation usually greater with the afferent arteriole stimulates a continuous renin release from than with the efferent one. They also tissues other than the kidney, such as sub- noticed that there was a significant correla- mandibular gland (Gresik et al., '78; Bing & tion of the contact area of the GoCs with Paulsen, '79), anterior pituitary (Celio et al., the macula densa on the one side and with '80; Grammer et al., '83), pineal and brain the afferent arteriole on the other, and (Celio et al., '80), and uterus (Hackenthal this pointed to the GoCs as the morpholog- et al., '80), to maintain sodium balance and ical link between the tubular and vascular to stabilize blood pressure. This results parts of the JGA. Then, they emphasized in reducing the extent of the JGC layer in that a "flow of information" from the the afferent arterioles to the normal level. macula densa via the GoCs to the afferent The spatial relationship between the arteriole is morphologically possible, and structural components of the JGA has been the direct contact areas between the macula intensively studied in relation to the feed- densa and the afferent or the efferent back mechanism in the JGA. Barajas and arterioles were not correlated with any of Latta ('63) have first studied the three- the other parameters. The assumption dimensional structure of the JGA at both that the GoC field may act as a functional the light and electron microscopic levels, unit taking part in the feedback mechanism and described that the efferent arteriole of the JGA was supported by freeze-fracture is an integral part of the juxtaglomerular studies (Pricam et al., '74; Boll et at, '75; functional unit, because it is more intimate- Forssmann & Taugner, '77; Taugner et al., '78) and a three ly related to the macula densa than in the -dimensional analysis of the afferent arteriole and has granular cells in GoC at the electron microscopic level its wall. Barajas ('70) has further examined (Spanidis et al., '82). These studies revealed the anatomical relationship between the a gap junctional coupling between the tubular and vascular components by serial- cellular components of the JGA, such as section electron microscopy, and distin- the JGCs, vascular smooth muscle cells, guished two types of contact between the the GoCs and the mesangial cells. Similar two components, permanent or irreversible findings were obtained in the present study, and reversible types, which are closely and in addition, a wide variety of the mor- related to the control mechanism of renin phological changes in the GoC field were secretion. While, a number of observations detected through experimentation. Espe- contrary to these results have been reported. cially, after 1-day-dehydration the GoC Though at the light microscopic level, field appeared smaller in size than that Faarup ('65) mentioned that the contact in other groups and had a pyramidal shape between the macula densa and both the with a sharp apex in many occasions. Con- afferent and efferent vessels is variable and sidering a significant change in extent of the contact with the afferent arteriole is the JGC layer as well as elevation of PRA slightly more common than that with the and blood pressure after 1-day-dehydration, efferent one. And also, Christensen and such morphological alterations of the GoC JG Apparatus after Water Deprivation 405

field may reflect a functional phase of IV. Freeze-fracturing of membrane surfaces. the JGA. And, this is obviously related Cell Tiss. Res., 161 : 459-469, 1975. 5) Mule, C. P., Scholz, H., Hackenthal, E., to changes in the spatial relationships Nobiling, R. and Taugner, R.: Epithelioid between the vascular components, which cells: membrane potential changes induced by is probably caused by contraction of the substances influencing renin secretion. Mol. GoCs. That is, the more acute angle both Cell. Dndocrinol., 45: 37-47, 1986. the afferent and efferent arterioles form 6) Cain, H., Boss, J. H. and Egner, E.: The at the vascular pole, the smaller the GoC bivalence of juxtaglomerular cells in the maturing rat kidney. A comparative study of field will be in size. Thus, it is presumed secretory and conractile potential. Virchow's that the GoC field as a functional center Arch. A Path. Anat. and Histol., 378: 111- of the JGA act not only to accerelate 120, 1978. renin secretion by stimulating the JGCs 7) Celio, M. R., Clemens, D. L. and Inagami, with a gap junctional coupling among the T.: Renin in anterior pituitary, pineal and neuronal cells of mouse brain. Immunohisto- cellular elements but also to control blood chemical localization. Biomed. Res., 1: 327- circulation in the glomerular capillaries by 431, 1980. changing the angle formed with the vessels 8) Christensen, J. A., Mayer, D. S. and Hohle, A.: and the Bowman's capsule. The structure of the human juxtaglomerular apparatus. A morphometric, light microscopic study on serial sections. Virchow's Arch. A Acknowledgement Path. Anat. and Histol., 367: 83-92, 1975. 9) Christensen, J. A. and Bohl, A.: The juxta- The author wishes to thank Dr. Atsushi glomerular apparatus in the normal rat Ichikawa, Professor of Anatomy, Yokohama kidney. Virchow's Arch. A Path. Anat. and City University School of Medicine, for his Histol., 379: 143-150, 1978. 10) Christensen, J. A., Bjaerke, H. A., Mayer, D. critical reading of the manuscript, and also S. and Bohle, A.: The normal juxtaglomerular she is grateful to Dr. Misao Ichikawa, As- apparatus in the human kidney. A morpholog- sociate Professor of Anatomy, for her ical study. Acta anat. 103: 374-384, 1979. advices and discussion. 11) Desormeaux, Y., Ballak, M., Benchimol, S., Lacasse, J., Cantin, M., and Genest J.: Synthe- sis and migration of proteins and glyco- References proteins in juxtaglomerular cells of sodium- deficient rats. Cell Tiss. Res. 222: 53-67, 1) Barajas, L.: The ultrastructure of the juxta- 1982. glomerular apparatus as disclosed by three- 12) Edelman, R. and Hartroft., P. M.: Localiza- dimensional reconstructions from serial sec- tion of renin in juxtaglomerular cells of tions. The anatomical relationship between rabbit and dog through the use of fluorescent the tubular and vascular components. J. antibody technique. Circ. Res., 9: 1069-1077, Ultrastr.Res., 33: 116-147,1970. 1961. 2) Barajas, L. and Latta, H.: A three-dimen- 13) Faarup, P.: On .the morphology of the juxta- sional study of the juxtaglomerular apparatus glomerular apparatus. Acta anat., 60: 20-38, in the rat. Light and electron microscopic 1965. observations. Lab. Invest., 12: 257-269, 14) Faraggiana, T., Gresik, E., Tanaka, T., Ina- 1963. gami, T. and Lupo, A.: Immunohistochemical 3) Bing, J. and Poulsen, K.: In mice agressive localization of renin in the human kidney. J. behavior provokes vase increase in plasma Histochem. Cytochem., 30: 459-465, 1982. renin concentration, causing only slight, if 15) Forssmann, W. G., Ito, S., White, E., Aoki, any, increasein blood pressure. Acta physiol. A., Dym, M., and Fawcett, D. W.: An im- Scand.,105: 64-72, 1979. proved perfusion fixation method for the 4) Boll, H. U., Forssmann,W. G. and Taugner, testis. Anat. Rec. 188: 307-314, 1977. R.: Studies of the juxtaglomerularapparatus. 16) Forssmann, W. G. and Taugner, R.: Studies 406 S. Kidokoro

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