The venous sinus of Kelch (VSK) represents a rare but clinically significant venous variant of the middle cranial fossa, with very limited documentation in the existing literature. This study aimed to understand the morphology, course, and morphometry of VSK along with associated variations in the drainage pattern of the superficial middle cerebral vein (SMCV) and middle meningeal sinus (MMS). This study was conducted over the period from 2022 to 2025 at Zoram Medical College and Hospital, Aizawl, Mizoram. In the present study, VSK was observed in 9.26% of the 54 middle cranial fossae examined from 27 cadavers. Moreover, SMCV and MMS, which normally drain into either the spheno-parietal sinus or cavernous sinus, drained into VSK. From an embryological perspective, VSK can be understood as a persistent primitive tentorial sinus (PTS). The variable course and termination of PTS may also result in other reported venous variants like Spheno-basal sinus, Spheno-petrosal sinus and Petro-basal sinus, which underscore the complexity of venous adaptations influenced by hemodynamic factors. Clinically, awareness of such variants is crucial for accurate radiological interpretation and for minimising the risk of iatrogenic injury during surgical and endovascular procedures involving the middle cranial fossa. Importantly, recognition of these alternative venous pathways may have future implications in facilitating novel endovascular approaches for neuromodulation, targeted therapy, and minimally invasive access to the temporal lobe and trigeminal nerve.
A mouse lymph node develops inside of five lymph sacs in the trunk. However, there are uninvestigated, numerous peripheral nodes. We chose histological sections from 38 human fetuses at approximately 8-31 weeks of gestational age (36 to 260 mm of crown-rump length). Three sites of the extremity and seven sites of the trunk were examined. Lymphocyte aggregations developed within the jugular, para-aortic and iliac lymph sacs by 10 weeks. The aggregation lost lymph endothelia at the lumen side and, in the external side, it was attached to the surrounding mesenchymal tissue. Shortly thereafter, in place of the sac endothelia, abundant lymph vessels (LVs) surrounded the aggregation. In the posterior intercostal space, two to seven LVs fused to build a small sac-like structure and, within it, a lymphocyte aggregation developed by 12 weeks and maintained a contact to the surrounding mesenchymal tissue. The same manner was seen in the inguinal, popliteal and cubital regions. In the jejunal mesentery, LVs drastically increased in thickness at 9-11 weeks and, shortly thereafter, they fused to build a very long sac-like structure. However, in the pulmonary hilum at 9-10 weeks, LVs did not fuse together but simply thickened. Thus, keeping a wide mesenchymal connection, a lymphocyte aggregation protruded into a single LV. Being independent of the lymph sac, lymphocytes aggregated in the mesenchymal tissue adjacent to peripheral LVs, followed by its protrusion into a sac-like structure that was usually built by fusion of multiple LVs or a thickened LV.
The circumaortic left renal vein (CLRV) is a critical retroperitoneal vascular variant. Current classification systems frequently omit possible morphologies. This study aims to delineate intricate CLRV patterns and propose a preliminary classification framework. Contrast-enhanced abdominal computed tomography (CT) scans of 380 adult patients (199 males and 181 females, with a mean age of 63.8±15.1 years) were retrospectively evaluated using multiplanar and three-dimensional volume-rendered reconstructions. CLRV variants were categorized into four groups: Type A (bifurcation), Type B (independent double veins), Type C (single interconnection close to the hilum), and Type D (double interconnection). Seventeen CLRV cases were identified, demonstrating a prevalence of 4.5% (10 females, 7 males). Type A was observed in 8 cases (2.1%), Type B in 2 cases (0.5%), Type C in 6 cases (1.6%), and Type D in 1 case (0.3%). The unique Type D configuration featured a double anastomosis with a renal artery passing between the interconnections. A statistically significant association was found between the morphological type and vertebral span (P=0.002), where interconnected variants (Types C and D) exhibited a significantly narrower span (0.9±0.1 vertebrae) than non-interconnected types (1.8±0.8 vertebrae); however, this finding must be interpreted cautiously due to the small subgroup sizes. This novel classification system successfully bridges a literature gap by accounting for complex configurations, offering an exploratory anatomical map to enhance safety during retroperitoneal surgeries and renal transplantations.
