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.

Striated muscle insertions into the skin and mucosa are present in the head, neck, and pelvic floor. We reexamined the histology of these tissues to elucidate their role in transmission of the force. We examined histological sections of 25 human fetuses (gestational ages of ~11–19 weeks and ~26–40 weeks) and 6 cadavers of elderly individuals. Facial muscle insertion or terminal almost always formed as an interdigitation with another muscle or as a circular arrangement in which muscle fiber insertions were sandwiched and mechanically supported by other muscle fibers (like an in-series muscle). Our examination of the face revealed some limited exceptions in which muscle fibers that approached the dermis were always in the nasalis and mentalis muscles, and often in the levator labii superioris alaeque nasi muscle. The buccinator muscle was consistently inserted into the basement membrane of the oral mucosa. Parts of the uvulae muscle in the soft palate and of the intrinsic vertical muscle of the tongue were likely to direct toward the mucosa. In contrast, the pelvic floor did not contain striated muscle fibers that were directed toward the skin or mucosa. Although ‘cutaneous muscle’ is a common term, the actual insertion of a muscle into the skin or mucosa seemed to be very rare. Instead, superficial muscle insertion often consisted of interdigitated muscle bundles that had different functional vectors. In this case, the terminal of one muscle bundle was sandwiched and fixed mechanically by other bundles.

We used a scanning electron microscope for identification of the two ticks which were found parasitic on two women.
(1) The patients were women of 69 and 62 years old.The main complaints were a tumour-formation on the skin of the upper abdominal region with itching in one case and the pain at the cicatrice of a past operation of the chest in another.In both cases a purulent inflamation appeared after 7 to 10 days at the site of bite and healed after 10 to 14 days with pigmentation.
(2) In our study through a scanning electron microscope we examined the morphological characters of marginal body setae, porose area, internal as well as external spurs of coxa I, and genital pore. The scanning electron microscope was effective especially to observe marginal body setae, spiracular plate, and internal as well as external spurs of coxa I, which are important for discriminating Ixodes nipponensis from Ixodes persulcatus.
We would expect that the morphological and physiological study of Ixodes species will develop hereafter concurrently with the parasitism of man by Ixodes nipponensis from the epidemiological standpoint.