Contents

Original articles:

1. Scanning and transmission electron microscopic study on a multilayered basement membrane in the pineal organ of the ayu Plecoglossus altivelis. (Furukawa E)
   
2. Obliteration of the lymphatic trunks draining diaphragmatic lymph causes peritoneal fluid to enter the pleural cavity. (Ohtani Y; Arch Histol Cytol, 1997 Dec)
   
3. Demonstration and organization of duct-associated lymphoid tissue (DALT) of the main excretory duct in the monkey parotid gland. (Matsuda M)
   
4. Distribution and co-localization of nitric oxide synthase and argininosuccinate synthetase in the cat hypothalamus. (Isayama H)
   
5. The effects of basic fibroblast growth factor, transforming growth factor-alpha, and transforming growth factor-beta on mesenchymal cells in the rabbit phallus: an in-vitro study. (Katsuki M)
   
6. Effects of colchicine on amoeboid microglial cells in the postnatal rat brain. (Kaur C)
   
7. Desmin and actin filaments in membrane-cytoskeletal preparations of the electric tissue of Electrophorus electricus, L. (Mermelstein CS)
   
   

Summary

Title
Scanning and transmission electron microscopic study on a multilayered basement membrane in the pineal organ of the ayu Plecoglossus altivelis.

Author
Furukawa E; Omura Y

Address
Laboratory of Animal Information Biology, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.

Summary
The pineal organ possesses highly fenestrated capillaries, and is devoid of the so-called blood-brain barrier. The present study indicated that the pineal epithelium of the teleost fish, ayu Plecoglossus altivelis, possesses an unusually thick and convoluted basement membrane (2.2-2.4 microm in width) which is visible even under the light microscope. This pineal basement membrane was observed by scanning and transmission electron microscopy and its detailed composition and relationships with the fenestrated capillaries and the perivascular space were investigated. As the basement membrane was composed of three to eight layers of basal laminae interspersed with laminae lucidae, we termed it the "multilayered basement membrane". In consideration of our previous demonstration that macromolecules such as HRP are trapped by the basement membrane, it is suggested that this multilayered basement membrane may prevent foreign substances from reaching the pineal epithelium.

Title
Obliteration of the lymphatic trunks draining diaphragmatic lymph causes peritoneal fluid to enter the pleural cavity.

Author
Ohtani Y; Ohtani O

Address
Second Department of Internal Medicine, Okayama University School of Medicine, Japan.

Summary
Pathways of peritoneal fluids to the pleural cavity in the rat were investigated by light microscopy and transmission electron microscopy (TEM). Intraperitoneally injected India ink was demonstrated to enter the subperitoneal lymphatics through lymphatic stomata, and to drain through the subpleural collecting lymphatics, into the parasternal, paravertebral and mediastinal lymphatic trunks as well as the thoracic duct. Five to 10 min after the intraperitoneal injection of India ink, the parasternal lymphatic trunk was ligated at the third intercostal space. Thirty minutes, 1 h, or 2 h after the ligation of either the right or the left trunk, India ink was macroscopically recognized only around the ligated trunk. When the right and left trunks were simultaneously ligated, India ink leaked around both trunks. Five hours after the ligation of both trunks, a massive amount of ink was located in the interstitium of the anterior thoracic wall. TEM revealed carbon particles passing through gaps of the lymphatic endothelial cells into the interstitial space, and partly reaching the mesothelial surface lining the anterior thoracic wall. Results show that obstruction or narrowing of the lymphatic trunks draining the diaphragmatic lymph causes a hydrothorax, indicating that this is at least one mechanism causing this during continuous ambulatory peritoneal dialysis and diseases with ascites.

Title
Demonstration and organization of duct-associated lymphoid tissue (DALT) of the main excretory duct in the monkey parotid gland.

Author
Matsuda M; Ina K; Kitamura H; Fujikura Y; Shimada T

Address
Department of Anatomy, Oita Medical University, Japan.

Summary
Duct-associated lymphoid tissue (DALT) of the main excretory duct in the monkey parotid gland was first demonstrated by light microscopy and by transmission and scanning electron microscopy. The DALT included a follicular area, a parafollicular area and a specialized overlying epithelium with distinct fine-structural elements. There was usually a solitary lymphoid follicle located in the subepithelial area near the orifice of the parotid duct. The lymphoid follicles typically had a distinct germinal center. Numerous immune cells often infiltrated into the epithelium overlying the lymphoid follicle. The superficial epithelial cells of the DALT were larger and flatter than the ordinary duct epithelial cells, and had short irregular microvilli on their luminal surface. They were also in close contact with immune cells such as dendritic cells and lymphocytes. Goblet cells were rare in this area. In addition, bacteria, seen at the duct orifice, were sometimes taken up by the flattened epithelial cells near the orifice. Latex microspheres administrated as particulate antigens at the duct orifice were selectively taken up by the flattened epithelial cells and also by the intraepithelial dendritic cells of the DALT. These morphological findings suggest that the epithelial cells of the DALT in parotid glands take up antigens from the duct lumen and transport them to adjacent immune cells, and that the DALT in parotid glands may serve as one of the inductive sites in the common mucosal immune system.

Title
Distribution and co-localization of nitric oxide synthase and argininosuccinate synthetase in the cat hypothalamus.

Author
Isayama H; Nakamura H; Kanemaru H; Kobayashi K; Emson PC; Kawabuchi M; Tashiro N

Address
Department of Anatomy, Kyushu University School of Medicine, Fukuoka, Japan.

Summary
Argininosuccinate synthetase (ASS) and nitric oxide synthase (NOS) comprise part of the cyclic metabolic pathway to produce nitric oxide (NO). ASS is one of the arginine synthesis enzymes which synthesizes argininosuccinate from aspartate and citrulline, and NOS forms NO and citrulline from arginine. This study examines the localization of ASS and NOS in the cat hypothalamus using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and immunohistochemistry against ASS and NOS. NADPH-d positive and/or ASS-immunoreactive neurons were localized in the following areas: the anterior hypothalamic area, the anterior hypothalamic nucleus, the supraoptic nucleus, the suprachiasmatic nucleus, the periventricular complex, the paraventricular nucleus, the parvocellular nucleus, the lateral hypothalamic area, the dorsomedial hypothalamic nucleus, the dorsal hypothalamic area, the posterior hypothalamic area, and the supramammillary nucleus. NOS and ASS double-labeled neurons were found in the anterior hypothalamic area, the supraoptic nucleus, the central part of the paraventricular nucleus of the hypothalamus, the lateral hypothalamic area, ventral part of the parvocellular hypothalamic nucleus, the posterior hypothalamic area, and the supramammillary nucleus. Double-labeled neurons in the hypothalamus comprised 20.7-32.0% of ASS-immunoreactive neurons and 10.2-26.3% of NOS-immunoreactive neurons. The results suggest the existence of the 'NO cycle' in situ and the physiological importance of NO and argininosuccinate in several regions of the cat hypothalamus.

Title
The effects of basic fibroblast growth factor, transforming growth factor-alpha, and transforming growth factor-beta on mesenchymal cells in the rabbit phallus: an in-vitro study.

Author
Katsuki M; Furukawa H; Doi Y; Hamasaki K; Nishino T

Address
Department of Anatomy, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.

Title
Effects of colchicine on amoeboid microglial cells in the postnatal rat brain.

Author
Kaur C

Address
Department of Anatomy, Faculty of Medicine, National University of Singapore, Singapore.

Source
Arch Histol Cytol, 60(5):453-62 1997 Dec

Abstract
The present study was conducted to examine the response of amoeboid microglial cells in the postnatal rat brain to colchicine administration. One-day-old postnatal rats were given intraperitoneal injections of colchicine and sacrificed at 7, 14 and 21 days of age. In rats killed at 7 days age, the number of OX-42, OX-18 and ED1 positive amoeboid microglial cells was considerably reduced when compared with the control rats. At 14 and 21 days, the number of cells immunoreactive with the above antibodies was comparable to that of the control rats. The intensity of the immunoreaction with the various antibodies was also comparable in colchicine injected and control rats. When rhodamine isothiocyanate (RhIC) was administered, amoeboid microglial cells emitted a bright fluorescence in control rats as well as in colchicine-injected rats, although in the latter, the number of RhIC labelled cells was considerably reduced. With the antibody bromodeoxyuridine a large number of stained cells were observed in the control rats. On the other hand, occasional labelled cells were recognized in colchicine-injected rats. Apoptotic amoeboid microglial cells were observed in 4-day-old colchicine-injected rats. At the electron microscopic level, amoeboid microglial cells in colchicine-injected rats killed at 7 days of age showed a large number of phagosomes in their cytoplasm compared with the corresponding control rats. At 14 and 21 days, in colchicine-injected and control rats, amoeboid microglial cells did not display any noticeable differences. It is concluded from the present study that colchicine suppresses the number of amoeboid microglial cells, and that this may be attributed to the antimitotic effect of the drug as well as apoptosis induced by it; the phagocytic activity, however, was not affected. The cells returned to their normal population and morphological features once the drug was discontinued, indicating the reversible nature of the drug effect.

Title
Desmin and actin filaments in membrane-cytoskeletal preparations of the electric tissue of Electrophorus electricus, L.

Author
Mermelstein CS; Benchimol M; Taffarel M; Cristina M; Cordeiro R; Chagas C; Moura Neto V

Address
Departamento de Histologia e Embriologia, Instituto de Ci^encias Biomｴedicas, Centro de Ci^encias da Saｴude, Universidade Federal do Rio de Janeiro, Brazil.

Summary
The electrocyte of the electric organ of the electric eel, Electrophorus electricus, L was investigated by light and electron microscopy as well as immuno-electron microscopy, in order to clarify the fine structures and distribution of cytoskeleton filaments and their relations to proteins, especially desmin and actin. Cytoskeleton-enriched fractions of the electrocytes were analysed with SDS-PAGE. It was verified that a meshwork of filaments was distributed in the electrocytes, more abundantly in the anterior than in the posterior part of the cell, and that this could be associated with membrane invaginations. Desmin and actin were the components of this meshwork, suggesting that desmin intermediate filaments and actin filaments might play a role in the maintenance of the morphology of electrocytes and, as an intracellular filamentous meshwork, they may contribute to the organization of the components of membranes and papillae formation on the anterior face of the electrocytes.