Anatomy of the levator claviculae, with an overview and a literature survey.

We report here an anatomical study of the levator claviculae discovered during an anatomical dissection course for medical students. The muscle was identified on the left side, and followed a typical topography to previous detections, originating from the transverse process of the fourth cervical vertebra and attaching to the upper facet of the middle part of the clavicle. Innervation to this muscle came from both the third and fourth rami of the cervical spinal nerves. Blood supply to the muscle could not be identified clearly. In this report, we undertook a comprehensive literature survey of this muscle dating back ca. 170 years, and attempted to ascertain the phylogenic and ontogenetic explanations for the development of this muscle.

Histochemical analysis of renal dysplasia with ureteral atresia.

Unilateral small kidney with ureteral obstruction was discovered in a 74-year-old female cadaver during an anatomical dissection course. In order to elucidate the histogenesis of renal dysplasia, we carried out histochemical and immunohistochemical analyses. On macroscopic view, the kidney was approximately 3 cm in length, 2 cm in width and weighed only 9 g. Although the ureter ran from the renal hilus to the bladder, its width was under 2 mm. The renal parenchyma was extremely thin and there was a large congested vein in the renal sinus. On microscopic examination of the kidney, we observed that numerous developing renal tubules had cytokeratin-positive epithelia, most of which were surrounded by concentric fibrosis. However, we could not detect any structures resembling the collecting duct, renal tubules, renal pelvis, or glomeruli. The concentric mesencymal fibrous tissue surrounding the immature renal tubules contained the smooth muscles that were positive for h-caldesmon. Serial sections of the ureter revealed several small and discontinuous lacunae lined by cuboidal and transitional epithelium, which did not constitute a patent lumen through the bladder. This case is a rare case of renal dysplasia with defect in recanalization of the ureteral bud during the early developmental stage.

Rare multiple combined anomaly of the vertebral vessels and bronchial artery.

Reported herein is a rare case of multiple vascular anomalies involving the vertebral vessels and the bronchial artery. In the present case the vertebral artery, which normally originates from the subclavian artery, arose directly from the cranial side of the aortic arch, just between the left common carotid and subclavian artery. Furthermore, the bilateral entry of the vertebral artery deviated to the upper level of the transverse foramen of the cervical vertebrae (C5). In addition, the left vertebral vein went through the transverse canal via the 5th and 7th transverse foramen, and drained into the left venous angle. Another conspicuous variation observed in this cadaver was the bronchial artery stemming from the left subclavian artery. This phenotype is an additional branch of bronchial arteries, which in normal cases arises from the descending aorta. These two anomalies could be explained by the deviation of the anlage for the left subclavian artery. The present report should be of interest for the clinician with regard to vascular anomalies in the neck and thoracic region, and may give insight into elucidating the developmental mechanism of angiogenesis.

Large-caliber persistent sciatic artery with aneurysm.

Herein is reported a rare case of right persistent sciatic artery (PSA) in the cadaver of a 96-year-old woman who did not have any clinical manifestations related to this anomaly when alive. The anomalous PSA originated from the internal iliac artery, directed toward the infrapiriform foramen, and descended the dorsal side of the thigh. Approximately 20 mm inferior to the infrapiriform foramen, the PSA formed a relatively large aneurysm elongating for approximately 30 mm in length. It then passed under the long head of the femoral biceps muscles, and reached the popliteal fossa, maintaining a constant caliber (approx. 13 mm) as it went down distally. In contrast, the femoral artery was very narrow, and tapered at the level of the knee joint. In addition, the popliteal vein gave rise to two branches, one ran along with the sciatic artery and the other pierced the adductor muscles, and appeared on the ventral side of the thigh. It then drained into the deep femoral vein, which reached the pelvis via the femoral vein. The present case is an interesting example for clinicians who work in pelvic surgery.

Mitochondrial accumulation in the distal part of the initial segment of chicken spinal motoneurons.

The axonal initial segment is the initiation site of action potentials and is characterized morphologically by a dense undercoating and fascicles of microtubules connected by cross-bridges. In order to analyze subcellular structures in the initial segment, we made serial transverse sections of initial segments of identified chicken motoneurons by retrograde transport of horseradish peroxidase (HRP) injected into the muscle. The mean (+/-SD) length of the initial segment was 28.1+/-2.3 microm (n=6). Mitochondria accumulated in the distal part of the initial segment, which was 1.4-6.9 microm in length (5-23% of the total length of the initial segment). In the transverse section of the distal part, mitochondrial density was 15.8+/-6.2% (n=5), while in the middle and proximal parts it was 6.1+/-1.6% and 5.6+/-1.4%, respectively. Mitochondrial accumulation was observed in common in phasic and tonic motoneurons in the chicken, and also observed in the distal part of the initial segment of the large ventral horn neurons of the chicken without HRP injection. These findings suggest that accumulated mitochondria play an important role in maintaining the physiological function of the distal part of the motoneuron initial segment.