In a student course of gross anatomy dissection at Kanagawa Dental University in 2011, we encountered anomalous case of the right subclavian artery arising from the aortic arch as the last branch in an 84-year-old Japanese male cadaver. The anomalous artery ran obliquely upward, passed behind the esophagus and trachea, and ultimately ran toward right scalene gap. The area of distribution of the anomalous artery was normal. We report a case of retroesophageal right subclavian artery, and discuss its development, or relation with the thoracic duct, and its clinical importance. Despite this type of variation being relatively rare, reports on such a case have been accumulating. Owing to the recent development of CT and MRI, the number of clinical reports on this anomaly has been increasing.

The teres major and latissimus dorsi muscles (TM, LD) are considered to be the so-called brother muscles. Actually, being similar to the TM, an uppermost part of the LD usually arises from the scapular plate. In embryos of 11 mm CRL, anlagen of the TM and LD appeared to be fused to provide a single mass at an angle between the axillary and radial nerves. However, splitting had already finished in not only the TM and LD but also the other muscles at and around the shoulder in specimens of 14 mm CRL. Thus, muscle splitting at the region appeared to occur simultaneously at a short stage of 12-13 mm CRL.The TM and LD carried a common tendon still at 6 weeks (14-16 mm CRL), but their muscle bellies were separated clearly. A concept of brother muscles might be applied to the TM and LD according to a bias from the gross and comparative anatomy, not from the embryological view.

The superior mesenteric vein was considered to develop in situ in the midgut mesentery secondary to regression of the left vitelline vein. We revisited the morphology using serial sections of 20 embryos at 5-6 weeks (CRL 9-15 mm). The regressing vitelline vein provided a long peritoneal fold in the immediately superior side of the midgut mesentery containing the thick superior mesenteric artery. Notably, in a half of specimens, there were tissue clefts along the superior mesenteric artery in the mesentery and they were communicated with the left vitelline vein at the superior end of the peritoneal fold. The tissue clefts appeared not to carry the endothelial lining. We considered the cleft as the initial superior mesenteric vein. Conversely, the initial vein seemed not to develop from budding or venous plexus.

Interleukin-18 (IL-18), which is involved in the inflammatory response, is also found in the cerebral cortex. IL-18 receptor-immunoreactive (IL-18R-ir) neurons are present in layer V of the retrosplenial cortex (RSC). In the adult IL-18 knock out (KO) mice, no IL-18R-ir neurons but many degenerated neurons are present in layer V of the RSC, suggesting that any changes in the neurons of layer V have occurred during postnatal development. We examined changes of IL-18R expression during postnatal development. In the wild-type mice, many IL-18R-ir neurons were present in layers II, III and VI of the RSC in 2-week-old mice, whereas they were sparsely observed in only layer III in 3-week-old mice. No IL-18R-ir neurons were present in 4- and 5-week-old mice. In older than 6-week-old mice, many IL-18R-ir neurons were present in layers V and VI. The IL-18KO mice showed IL-18R-ir neurons in layers II, III and VI at 2-weeks-old, and a few in layer III at 3-week-old mice, similar to that in the wild-type mice. No IL-18R-ir neurons were found in mice older than 4 weeks of age. Thus, IL-18 or IL-18R seem to be involved in the construction of neural circuits corresponding to events after 3-weeks of age.

The purpose of this study is to describe the Hasner's membrane which is the main factor of congenital nasolacrimal duct obstruction. Hasner's membrane at the nasal end of the fetal nasolacrimal duct (NLD) is considered to rupture at and after birth. However, topographical anatomy around the membrane as well as a mechanism of rupture seems to be still obscure. We observed frontal or sagittal sections of 20 late-stage fetuses (28-33 weeks) and found the on-going rupture in 2 specimens. The present sections demonstrated that 1) the nasal dilation was not a simple ball-like structure but extended posteriorly and laterally; 2) dilation of the NLD consistently involved the lacrimal sac; 3) Hasner's membrane and ductal mucosal layer contained no macrophages and no or few arteries and nerves. The posterior extension of the NLD end ranged from 1-2 mm, while the lateral extension 3-5 mm although a site of the thinnest membrane varied in location between specimens. Moreover, the thickest NLD due to dilation was in the slightly orbital or upper side of the nasal end. Therefore, before surgical treatment of Hasner's membrane, evaluation using medical images seems to be necessary. Since the nasal epithelium on Hasner's membrane was most likely to destroy earlier than the NLD mucosal lining, observations of the membrane from the nasal cavity seemed helpful for diagnosis at which site would be broken and when.

The superficial morphology of the acinus of the mandibular gland in rats, which corresponds to the submandibular gland in humans, is very difficult to observe under scanning electron microscope due to a closely adherent capsule. Therefore, we evaluated the most effective protocol for removing this capsule from the acinus using various solutions, at different temperatures and for different durations of soaking. Based on the data for 50 male Wistar rats, the most effective method was soaking in an 8 N hydrochloric acid solution at 60°C for 70 min, in a water bath, followed by soaking in a 0.1-0.2% collagenase solution at 37°C for 330-350 min.

We microscopically examined the dorsal lingual surface of an adult chimpanzee (Pan troglodytes). The tongue of the chimpanzee was about 13 cm long. Filiform papillae were distributed over the entire dorsal surface of the lingual body. There were many fungiform papillae scattered among the filiform papillae. At the posterior end of the lingual body, a triangular arrangement of the vallate papillae, with the apex of the triangle directed posteriorly, was observed. The filiform papillae on the lingual apex consisted of a main papilla and secondary papillae. The filiform papillae on the lingual body had several pointed processes. There were dome-shaped fungiform papillae scattered among the filiform papillae. The vallate papillae were surrounded by grooves and were flattened-oval shaped. Many foliate papillae were observed on the posterolateral regions of the tongue.

In the case of anatomical dissection as part of medical education, it is difficult for medical students to find the ciliary ganglion (CG) since it is small and located deeply in the orbit between the optic nerve and the lateral rectus muscle and embedded in the orbital fat. Here, we would like to introduce simple ways to find the CG by 1): tracing the sensory and parasympathetic roots to find the CG from the superior direction above the orbit, 2): transecting and retracting the lateral rectus muscle to visualize the CG from the lateral direction of the orbit, and 3): taking out whole orbital structures first and dissecting to observe the CG. The advantages and disadvantages of these methods are discussed from the standpoint of decreased laboratory time and students as beginners at orbital anatomy.