An anatomic study of the extensor tendons of the human hand.

A total of 548 upper limbs (276 right and 272 left hands) from Japanese cadavers were dissected. The arrangements of extensor indicis proprius, extensor digitorum communis (EDC), and extensor digiti minimi tendons and the intertendinous connections were studied. The most common pattern of extensor tendons was as follows: the index finger had a single EDC tendon, the middle finger had a single EDC tendon, the ring finger had a single EDC tendon, and the small finger had a single EDC tendon or a single common EDC tendon distributed to the ring and small finger. A single extensor indicis proprius tendon ran along the ulnar side of the EDC, and the extensor digiti minimi tendon consisted of 2 slips. Intertendinous connections were classified into 3 types: type 1 with a filamentous band, type 2 with a fibrous band, and type 3 with a tendinous band subdivided to r-shaped and y-shaped. The most common patterns were type 1 in the second intermetacarpal space (IMCS), type 3r in the third IMCS, and type 3y in the fourth IMCS.

Appearance of vascular endothelial growth factor (VEGF) in femoral head in the growing rat.

In this study, we examined the appearance of vascular endothelial growth factor (VEGF) in the femoral head of the growing rat using an immunocytochemical technique. Our results showed VEGF-immunopositive cells existed in the inner region and peripheral region of the femoral head at each developmental stage. In the 19-day-old fetus, immunopositive mesenchymal cells were demonstrated in the peripheral region of the femoral head. At 1 to 10 days after birth, VEGF immunoreactivities were observed in the osteoblasts, osteoclasts, periosteum, perichondrium and cartilage matrix of the femur. At 15 days after birth, VEGF immunoreactive chondrocytes appeared in the apex area of the femoral head. In this stage, the femoral head is still constituted by chondrocytes and no apparent vascular formation has been observed. Thereafter, the immunopositive chondrocytes in the femoral head increased in number. The penetration of capillaries was recognized within the ligament of the femoral head at 60 days after birth. The results indicate that some chondrocytes in the femoral head produce VEGF before the beginning of ossification, and that VEGF may play an important role in the penetration of blood vessels into the femoral head from the ligament of the femoral head.

Chronological study of the appearance of adenohypophysial cells in the ayu (Plecoglossus altivelis).

We previously reported the chronological appearance of adenohypophysial cells in freshwater teleosts using an immunocytochemical technique. The present study investigated the chronological appearance of adenohypophysial cells in the ayu, which is spawned and has its early development in brackish water, and the results were compared with those obtained in freshwater and seawater teleosts, as well as in other vertebrates. In the adult teleostean adenohypophysis, seven or eight types of secretory cells have been distinguished, each of which produce different hormones: prolactin (PRL), growth hormone (GH), thyroid stimulating hormone (TSH), gonadotropic hormones (GTH I and GTH II), adrenocorticotropic hormone (ACTH), melanophore stimulating hormone (MSH) and somatolactin (SL). In the pituitary of adult ayu, seven distinct types of glandular cells (PRL, GH, TSH, GTH, ACTH, MSH and SL cells) were identified. Chronologically, a few immunoreactive (ir)-PRL and ir-GH cells appeared in the ventral side of the pituitary one day before hatching. Then, just after hatching, ir-GTH cells were observed in the central to dorsal portion; ir-ACTH cells were found distributed in the anterior portion and some ir-MSH and a few ir-SL cells were seen in the posterior portion of the pituitary. Finally, a small number of ir-TSH cells were identified 50 days after hatching. These results differed from those obtained in other fishes previously reported with regard to the times of appearance of the PRL and GH cells. PRL cells appeared first, followed by GH cells in the freshwater teleosts, PRL and GH cells appeared at the same time in the brackishwater teleosts, while GH cells appeared first and PRL cells appeared last in the seawater teleosts. These results reflect the fact that PRL plays a major role in osmoregulation among freshwater teleosts, as compared with GH, which plays a similar role in seawater teleosts. It seems that both PRL and GH may play important roles in osmoregulation in brackishwater fish.

The fate of the compressed deformed spinal cord after decompressive surgery: MR imaging and histopathological findings in experimental studies.

The authors conducted a study in which they applied the spinal cord compression-decompression model in rabbits to investigate the morphological changes and histopathological findings in the deformed spinal cord over a long-term period after performing decompressive surgery. Throughout the experimental period, mangnetic resonance (MR) images were obtained frequently; after obtaining a final MR image, the spinal cord was dissected and underwent histological examination. Immediately after decompressive surgery, axial T1-wieighted MR imaging revealed an increase in the cross-sectional area of the spinal cord during the 1st and 2nd weeks. The spinal cord area achieved a peak at an average of 5.9 weeks after decompressive surgery, when it displayed isointensity on T1- and high-intensity on T2-weighted images. The main histological findings were spongy changes in the white matter, which persisted for 4 months postsurgery. There was a significant correlation between the presurgical spinal cord area and the postsurgical decreased number of motor neuron cells. Based on the MR imaging and histopathological studies, although the deformed spinal cord that underwent compression for 3 months was immediately restored morphologically after decompressive surgery, the change in quality in the spinal cord persisted at least 4 months.

Increase in number of Weibel-Palade bodies and endothelin-1 release from endothelial cells in the cadmium-treated rat thoracic aorta.

Male rats received daily intraperitoneal injections of cadmium sulphate (2.0 mg/kg) for 3 (Cd-3 group), 6 (Cd-6 group) and 8 days (Cd-8 group). The blood samples were prepared for endothelin (ET)-1 assay, and the thoracic aorta was investigated by both electron microscopy and immunoelectron microscopy using anti ET-1 sera. The plasma ET-1 concentrations of both Cd-6 and Cd-8 groups increased significantly in a cumulative dose-dependent manner. The cadmium-treated rat aorta showed an increase in the number of Weibel-Palade (WP) bodies in endothelial cells, and degranulation and exocytosis of WP bodies occurred exclusively in the Cd-8 group. Immunoreaction for ET-1 was localized preferentially in WP bodies of both cadmium-treated and control groups, and in the rough endoplasmic reticulum of the cadmium-treated groups only. Reactivity was also found on the WP bodies undergoing exocytosis in the Cd-8 group. Cadmium intoxication induces an increase in number of ET-1-storing WP bodies in the rat aorta endothelium. The enhancement of extracellular release of their contents by exocytosis results in elevation of the plasma ET-1 concentration.

Histochemical and immunological analyses of differentiating skeletal muscle fibers of the postnatal rat.

Fiber type differentiation as revealed by myosin ATPase activities and the immunological analysis of myosin light chains (MLC) by the Western blotting method were done on the postnatal rat soleus and extensor digitorum longus (EDL) muscles. In the soleus, type 1 (slow-twitch) muscle fibers gradually increase in percentage after postnatal day 10, and, in the EDL, the differentiation of type 2A and 2B (fast-twitch) muscle fibers is also pronounced between postnatal days 10 and 15. The present immunological analysis of MLC indicates that the antigenicity of Lc1S becomes more intense with a rapid decrease in antigenicity of Lc2F from postnatal day 7 in the soleus, while the antigenicity of Lc1F becomes noticeable during the same period in the EDL. These results suggest that the differentiation of slow-twitch fibers is mainly due to that of Lc1S in the soleus and the differentiation of fast-twitch fibers is mainly due to that of Lc1F in the EDL.

Cadmium toxicity in the thyroid gland of pregnant rats.

The toxic effects of cadmium on the thyroid gland of pregnant rats were studied with an electron microscope and an X-ray microanalyzer. Serum levels of thyroid hormones (T3 and T4) were also analyzed. Deterioration of the rough-surfaced endoplasmic reticulum occurred in the thyroid follicular epithelium on the fifth day of cadmium treatment. Large intracellular vacuoles, which arose from dilated cisternae of the rough-surfaced endoplasmic reticulum, were fused together, and marked swelling of the mitochondria was also noted. Thyroglobulin-secreting granules at the apical cytoplasm were decreased in number. By energy dispersive X-ray microanalysis, cadmium peaks were preferentially obtained from swollen mitochondria in the follicular epithelial cells. Serum levels of T3 and T4 were significantly decreased in cadmium-treated rats dams when compared to those of controls. In the present experiment, cycloheximide also caused degenerative changes in the rough-surfaced endoplasmic reticulum and the disappearance of thyroglobulin-secreting granules. Cycloheximide is a known inhibitor of protein synthesis on cytosolic ribosomes. These results indicated that accumulated cadmium in the mitochondria of thyroid follicular epithelial cells might disturb the oxidative phosphorylation of this organelle and the loss of energy supply possibly caused the inhibition of the synthesis and release of thyroid hormones.

Cadmium toxicity in perinatal rat hepatocytes: electron microscopy, X-ray microanalysis, and morphometric analysis.

Effects of cadmium on the fetal and postnatal rat hepatocytes were studied with an electron microscope and an X-ray microanalyzer. Pregnant and lactating Wistar rat dams at 15 and 21 days of pregnancy and at 3 days after delivery received intraperitoneal injections of cadmium sulfate (1 mg/kg body weight) for 3 days. On the day following the last injection, the livers were isolated from the fetal and suckling rats and provided for electron microscopy. The livers from the untreated fetal and newborn rats served as control. Large bile canaliculi, which were formed by five or more hepatocytes, were frequently observed in the cadmium-treated perinatal rat livers. The intercellular space between each adjacent hepatocyte was widened. By X-ray microanalysis, cadmium peaks were preferentially detected out from intramitochondrial granules of the cadmium-treated hepatocytes. By morphometric analysis, the increase both in the mitochondria volume and in the number of intramitochondrial granules was evident in the cadmium-treated hepatocytes when compared to those of control. These data suggest the preferential accumulation of cadmium in mitochondria of the hepatocytes interferes with the morphogenesis of the perinatal rat liver.

Cadmium toxicity to the cornea of pregnant rats: electron microscopy and x-ray microanalysis.

Cadmium toxicity to the cornea of pregnant rats was studied using the electron microscope and x-ray microanalyzer. In in-vivo experiments, severe corneal edema occurred in pregnant dams that received intraperitoneal injections of cadmium sulphate for 4 days during gestation, but not in nonpregnant rats. Prominent swelling of mitochondria and the occurrence of intra- and intercellular vacuoles in the corneal endothelium were observed only in pregnant dams. In in-vitro experiments, electron-dense deposits consisting of cadmium-oxine complexes were preferentially found in swollen mitochondria of the endothelial cells. Cadmium peaks were obtained from these deposits with x-ray microanalysis. These data suggest that the corneal edema observed after administration of cadmium may imply the disturbance of pump function and barrier function of the corneal endothelium due to the primary toxic effects of this metal on mitochondria.