The nasal mucosa and submucosa likely contain both vascular beds against cold and dry air and resident immunoreactive cells against various antigens. Therefore, a specific fibrous structure seems to be necessary. Using histological specimens from 20 elderly cadavers, we examined the nasal mucosal and submucosal architecture. The ciliated columnar epithelium of the nasal mucosa was characterized by 1) a thick basal lamina, 2) few elastin-positive fibers beneath the epithelium, that was quite different from the nearby mucocutaneous junction area with a thick layer (0.3–0.8 mm) of elastic and oxytalan fibers corresponding to the skin dermis, 3) CD34-positive cells distributing diffusely in the submucosal tissue, and 4) few smooth muscle actin (SMA)-positive fibers beneath the epithelium. Some of submucosal fibrous structure appeared to express both elastin and CD34. CD34-positive arterioles were abundant beneath the ciliated epithelium, but they appeared negative for SMA antibody that cross-reacts with endothelium. Notably, the ciliated columnar epithelium was thin in the lateral wall of the nasal cavity, while the inferior concha carried the thick pseudostratified columnar epithelium.Strangely, the inferior or palatal wall of the nasal cavity was covered by the thick stratified epithelium. We found SMApositive mucosal venous plexus in the lateral wall of nasal cavity, but the submucosa was filled with glands in the inferior concha. Vascular beds might be replaced by glands in the nasal submucosa. The site-dependent difference in the mucosal morphology as well as the absence of vascular beds might be a result of secondary change with aging.

Although human lymph node architecture varies by site, the intranodal distribution of interdigitating dendritic cells (DCs) remains poorly understood. To address this, we compared the morphology of submandibular, paratracheal, mesenteric, and inguinal nodes obtained from 24 donated cadavers. Immunoreactivity was evaluated by comparing these cadaveric nodes with surgically resected lymph nodes obtained from five old-aged patients with nonmetastatic cancer.Despite the limited number of dendritic cell-specific ICAM-3–grabbing nonintegrin (DC-SIGN)–positive cells (candidate DCs) in cadaveric specimens, these tissues were deemed suitable for analysis. The submandibular and paratracheal nodes exhibited a belt-like cortex, with paracortical lymph sinus extending from the subcapsular sinus and surrounding the follicle.In contrast, the mesenteric and inguinal nodes contained multiple island-like cortices separated by thick paracortical lymph sinuses. Endothelial cells lining all lymph sinuses showed reactivity for smooth muscle actin and DC-SIGN. Macrophages and candidate DCs were abundant in the paratracheal and mesenteric node sinuses but scarce in the submandibular and inguinal nodes. Notably, the medullary sinus in the submandibular and inguinal nodes was filled with fibrous tissue, and the surrounding paracortical sinuses formed a “sea” around the island-like cortices, often resulting in loss of nodal polarization.Although the proportional area occupied by candidate DCs per nodal section was almost the same at the four sites, the overlap between DCs and macrophage clusters was small in paratracheal and inguinal nodes. The amount of afferent lymph and the retention of efferent lymph might determine the site-dependent architecture. Therefore, in aged nodes, DCs were preferentially localized in the paracortical sinus.

The occipital bone squamosa (OCS) is unique because of its double origin from both endochondral and membranous bones. The present study attempted to demonstrate the process of connection between these two bone types. We examined sagittal and frontal histological sections from 29 human fetuses with a crown-rump length ranging from 38 to 328 mm (approximately 7–39 weeks of gestational age [GA]). An initial cartilage plate appeared in the posterior side of the fourth ventricle at GA 7–8 weeks and extended inferiorly to connect with the cartilaginous basioccipital and condyle. At GA 9–10 weeks, on the superior side of the cartilage plate, membranous bone fragments appeared and adopted an arrangement resembling a chain of irregularly-shaped beads.They did not form a complete plate-like bone until late-term. At GA 11–12 weeks, endochondral ossification centers appeared at the upper and lower ends of the cartilage plate. At GA 12–15 weeks, a bar-like periosteal bone developed near and superior to the upper ossification center. Notably, sinusoidal structures, which were surrounded by growing periosteal bones, contained islandlike clusters of calcified cartilage fragments. Therefore, the upper ossification center appeared likely to “migrate” downward and become distant from membranous bones. The extending periosteal bone reached and joined the membranous bone fragments.Consequently, the periosteal bones connected between the endochondral and membranous bones in the OCS. This connection was quite different from the other components of the calvaria, where membranous bones overlap the skull base cartilages at the margin.