The morphofunctional organization of the exocrine cells in the foregut of the red-eared slider turtle, Trachemys scripta, was investigated by histochemistry (PAS, AB pH1.0 and pH 2.5, HID-AB, Bowie), lectin-histochemistry (WGA, SBA, UEA, ConA, PNA, DBA, sialidase-SBA, sialidase-PNA, Paradoxical ConA), and immunohistochemistry (antipepsin, anti-α-H⁺, K⁺ ATPase) to detect regional differences and verify the existence of an oro-aboral gradient in gastric juice secretion. Observations showed that pharyngeal goblet cells have mucins with terminal residuals of GalNAc and sialic acid. In the oesophagus, sulphomucins in the goblet cells are progressively substituted by sialomucins and no glands are found. Gastric surface cells secrete mostly sialomucins with residuals of GlcNAc and GalNAc. The cardias presents glands with cells secreting mostly sialomucins, differing from the surface ones in having GalNAcα1,3GalNAc sequences. The fundus presents complex glands with main and lesser tubules. Cells in the main tubules secrete stable, class-III mucins with sialylated residuals of glucose and/or mannose, GalNAcα1, 3GalNAc, and Galβ1,3GalNAc sequences. In the lesser tubules, the oxynticopeptic cells are found, presenting pepsinogen granules and an affinity to the anti-α-H⁺,K⁺ ATPase, without any oro-aboral variation. The pyloric glands have a secretion similar to that of the neck cells of the fundic glands, consisting of stable, class-III mucins mostly sialylated with a high heterogeneity of residuals such as glucose and/or mannose, fucose, GlcNAc, and GalNAc. Mucins in the foregut are probably involved in several functions such as lubrication, protection against gastric juice, osmotic regulation to increase intestinal absorption, and protection against microbial injuries.

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5-hydroxytriptamine (5-HT) is an important transmitter for vessel constriction. The present study was performed to clarify the effect of 5-HT on smooth muscles in large- and small-sized cerebral and testicular arterioles by confocal microscopy, with special reference to intracellular Ca²⁺ concentration ([Ca²⁺]_i) dynamics. In cerebral vessels, 5-HT induced a [Ca²⁺]_i increase and the contraction of smooth muscle cells in large- and midsized arterioles (external diameters >50 μm) but not in small-sized arterioles. Conspicuous [Ca²⁺]_i changes by 5-HT were especially observed in the portions close to the cerebral arterial circle, and the 5-HT-induced responses were caused by both Ca²⁺ influx and mobilization. Experiments using agonists and antagonists also revealed that cerebral arteriole smooth muscles possess 5-HT1a, 1b, 2 (G-protein-coupled type), and 3 (ion channel type) receptors; specifically, 5-HT2 plays a major role in these responses. On the other hand, in testicular vessels, there were few regional differences among responses to 5-HT, and both large- and small-sized arterioles responded to 5-HT. The responses were caused by only Ca²⁺ mobilization mediated 5-HT1a and 2. These results indicate that arterioles in different tissues may respond to 5-HT in different manners. Regional differences and the size-dependent manner of responses to 5-HT in cerebral blood vessels also indicate that the regulatory mechanism of blood circulation is highly differentiated in each region of the central nervous system.

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To develop an experimental model and evaluate the effects of the magnitude and duration of pressure, the rat abdominal wall (25 × 20 mm) was subjected to compression either by a weight or by two magnets. In the weight compression tests, a steel plate was inserted under anesthesia into the rat peritoneal cavity, and the abdominal wall was compressed in situ between the underlying steel plate and a weight placed on the abdominal wall. This method resulted in moderate changes in the subcutaneous connective tissue and muscle at 100 mmHg (13.3 kPa) for 4 h, while some muscle damage was observed at 50 mmHg (6.7 kPa) for 4 h and at 100 mmHg for 2 or 3 h. In the magnet pinching tests, a magnet was inserted into the peritoneal cavity, and another magnet overlaid on the skin. Then the abdominal wall was compressed by the two magnets with or without anesthesia. The compression without anesthesia produced significant edema and injuries of the abdominal wall at 50 mmHg for 4 h and at 100 mmHg for 3 or 4 h, while the injuries incurred at 100 mmHg for 2 h were mild. Susceptibility to pressure was high in the muscle, moderate in the subcutaneous connective tissue, and low in the skin. The compression with anesthesia produced significantly milder injuries than those under anesthesia. These findings indicate that the difference in the extent of injuries between the weight compression and maget compression models are clearly attributable to the pentobarbital anesthesia induced during the compression. Results therefore show that experimental pressure ulcers should be examined in a waking condition and that magnet compression is a useful model for studying the pathogenesis of pressure ulcers.

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Continuously growing rodent incisors have a special epithelial structure for maintaining adult stem cells that shows a bulbous epithelial protrusion at the apical end and is referred to as an “apical bud”. Guinea pig cheek teeth (premolars and molars), also continuously growing teeth, have a complex crown shape consisting of plural cusps. The present study clarifies the existence of apical buds in guinea pig premolars/molars as it examines the relationship between the crown shape and the orientation of the apical buds by micro-computed tomography (μ-CT) and immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU). One premolar and three molar teeth in each side of the maxillae and mandibles assumed characteristic features: each horizontally-sectioned tooth showing a complex zigzag shape was composed of a core of dentin covered by a layer of enamel on all axial surfaces except the buccal of the uppers and the lingual of the lowers. Furthermore, four bulbous epithelial protrusions - including the stellate reticulum - were recognized in the apical end of each tooth, where slow-cycling long-term label-retaining cells resided 20 days after a peritoneal injection of BrdU. These data indicate that guinea pig premolars/molars have four apical buds where the epithelial adult stem cells reside. In contrast, rodent incisors, which show a single cone appearance, are covered by enamel on the labial side and possess only one apical bud. The results of this study suggest that plural apical buds, being arranged bucco-lingually and mesio-distally, produce the crown mold in a zigzag fashion.

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