A comparative anatomical and histological study on the presence of an apical splenic nerve in mice and humans.

The cranial pole of the mouse spleen is considered to be parasympathetically innervated by a macroscopic observable nerve referred to as the apical splenic nerve (ASN). Electrical stimulation of the ASN resulted in increased levels of splenic acetylcholine, decreased lipopolysaccharide-induced levels of systemic tumor necrosis factor alpha and mitigated clinical symptoms in a mouse model of rheumatoid arthritis. If such a discrete ASN would be present in humans, this structure is of interest as it might represent a relatively easily accessible electrical stimulation target to treat immune-mediated inflammatory diseases. So far, it is unknown if a human ASN equivalent exists. This study aimed to provide a detailed description of the location and course of the ASN in mice. Subsequently, this information was used for a guided exploration of an equivalent structure in humans. Microscopic techniques were applied to confirm nerve identity and compare ASN composition. Six mice and six human cadavers were used to study and compare the ASN, both macro- and microscopically. Macroscopic morphological characteristics of the ASN in both mice and humans were described and photographs were taken. ASN samples were resected, embedded in paraffin, cut in 5 µm thin sections where after adjacent sections were stained with a general, sympathetic and parasympathetic nerve marker, respectively. Neural identity and nerve fiber composition was then evaluated microscopically. Macroscopically, the ASN could be clearly identified in all mice and was running in the phrenicosplenic ligament connecting the diaphragm and apical pole of the spleen. If a phrenicosplenic ligament was present in humans, a similar configuration of potential neural structures was observed. Since the gastrosplenic ligament was a continuation of the phrenicosplenic ligament, this ligament was explored as well and contained white, potential discrete nerve-like structures as well which could represent an ANS equivalent. Microscopic evaluation of the ASN in mice and human showed that this structure did not represent a nerve, but most likely connective tissue strains. White nerve-like structures, which could represent the ASN, were macroscopically observed in the phrenicosplenic ligament in both mice and human and in the gastrosplenic ligament in humans. The microscopic investigation did not confirm their neural identity and therefore, this study disclaims the existence of a parasympathetic ASN in both mice and human.

Sympathetic nerve distribution in human lymph nodes.

Various lymph node functions are regulated by the sympathetic nervous system as shown in rodent studies. If human lymph nodes show a comparable neural regulation, their afferent nerves could represent a potential therapeutic target to treat, for example, infectious or autoimmune disease. Little information is available on human lymph node innervation and the aim of this study is to establish a comprehensive and accurate representation of the presence and location of sympathetic nerves in human lymph nodes. Since previous studies mention sympathetic paravascular nerves to occasionally extent into T cell-rich regions, the relation of these nerves with T cells was studied as well. A total number of 15 inguinal lymph nodes were resected from six donated human cadavers. Lymph node sections were stained with HE and a double T/B cell staining for evaluation of their morphology and to screen for general pathologies. A triple stain was used to identify blood vessels, sympathetic nerves and T cells, and, to study the presence and location of sympathetic nerves and their relation to T cells. To evaluate whether the observed nerves were en route to other structures or were involved in local processes, adjacent slides were stained with a marker for varicosities (synaptophysin), which presence is suggestive for synaptic activity. All lymph nodes contained sympathetic nerves, both as paravascular and discrete structures. In 15/15 lymph nodes, nerves were observed in their capsule, medulla and hilum, whereas only 13/15 lymph nodes contained nerves in their cortex. The amount of sympathetic nerves varied between compartments and between and within individuals. In general, if a lymph node contained more paravascular nerves in a specific compartment, more discrete nerves were observed as well. Occasionally, discrete nerves were observed in relation to T cells in lymphoid tissues of the cortex and medulla. Furthermore, discrete nerves were frequently present in the capsule and hilum. The presence of varicosities in a portion of these nerves, independently to their compartment, suggested a local regulatory function for these nerves. Human lymph nodes contain sympathetic nerves in their capsule, trabeculae, cortex, medulla and hilum, both as paravascular or as discrete structures. Discrete nerves were observed in relation to T cells and non-T cell-rich areas such as the hilar and capsular connective tissue. The presence of discrete structures suggests neural regulation of structures other than blood vessels, which was further supported by the presence of varicosities in a portion of these nerves. These observations are of relevance in further understanding neural regulation of lymph node immune responses and in the development of neuromodulatory immune therapies.

Where do human sperm and egg meet?

Summary: Although it is commonly accepted that fertilisation in humans occurs in the ampulla of the fallopian tube, the peritoneal cavity might represent an alternative fertilisation site. Studies substantiating both fertilisation sites were reviewed and new insights on the fertilisation site in humans are discussed, including their implications for reproductive medicine.

Splenic artery loops: Potential splenic plexus stimulation sites for neuroimmunomodulatory-based anti-inflammatory therapy?

INTRODUCTION: The splenic plexus might represent a novel neuroimmunomodulatory therapeutic target as electrical stimulation of this tissue has been shown to have beneficial anti-inflammatory effects. Tortuous splenic artery segments (splenic artery loops), including their surrounding nerve plexus, have been evaluated as potential stimulation sites in humans. At present, however, our understanding of these loops and their surrounding nerve plexus is incomplete. This study aims to characterize the dimensions of these loops and their surrounding nerve tissue. MATERIALS AND METHODS: Six formaldehyde fixed human cadavers were dissected and qualitative and quantitative macro- and microscopic data on splenic artery loops and their surrounding nerve plexus were collected. RESULTS: One or multiple loops were observed in 83% of the studied specimens. These loops, including their surrounding nerve plexus could be easily dissected free circumferentially thereby providing sufficient space for further surgical intervention. The splenic plexus surrounding the loops contained a significant amount of nerves that contained predominantly sympathetic fibers. CONCLUSION: The results of this study support that splenic artery loops could represent suitable electrical splenic plexus stimulation sites in humans. Dimensions with respect to loop height and width, provide sufficient space for introduction of surgical instruments and electrode implantation, and, the dissected neurovascular bundles contain a substantial amount of sympathetic nerve tissue. This knowledge may contribute to further development of surgical techniques and neuroelectrode interface design.

Sympathetic nerve tissue in milky spots of the human greater omentum.

Omental milky spots (OMSs), small lymphoid structures positioned in the greater omentum, are involved in peritoneal immune homeostasis and the formation of omental metastases. Sympathetic nerve activity is known to regulate immune function in other lymphoid organs (e.g. spleen and lymph nodes) and to create a favourable microenvironment for various tumour types. However, it is still unknown whether OMSs receive sympathetic innervation. Therefore, the aim of this study was to establish whether OMSs of the adult human greater omentum receive sympathetic innervation. A total of 18 OMSs were isolated from five omenta, which were removed from 3% formaldehyde-perfused cadavers (with a median age of 84 years, ranging from 64 to 94). OMSs were embedded in paraffin, cut and stained with a general (PGP9.5) and sympathetic nerve marker (TH and DBH), and evaluated by bright field microscopy. A T-cell, B-cell, and macrophage staining was performed to confirm OMS identity. In 50% of the studied OMSs, sympathetic nerve fibres were observed at multiple levels of the same OMS. Nerve fibres were represented as dots or elongated structures and often observed in relation to small vessels and occasionally as individual structures residing between lymphoid cells. The current study shows that 50% of the investigated OMSs contain sympathetic nerve fibres. These findings may contribute to our understanding of neural regulation of peritoneal immune response and the involvement of OMSs in omental metastases.

A Retrospective Analysis of Female Müllerian Duct Anomalies in Association With Congenital Renal Abnormalities.

STUDY OBJECTIVE: Müllerian (paramesonephric) duct anomalies (MDAs) are associated with several coexisting congenital abnormalities, including renal abnormalities. Although congenital renal abnormalities may remain asymptomatic, the consequences should not be underestimated. In both the literature and clinical practice, it remains necessary to improve awareness of the co-occurrence of different congenital renal abnormalities in women with MDAs. To gain further insight into this co-occurrence and to estimate whether guidelines for women with MDAs should be optimized, this study was performed. DESIGN: A descriptive retrospective analysis. SETTING: University Medical Centre Utrecht in the Netherlands. PARTICIPANTS: Women with MDAs diagnosed or treated between 1980 and 2015. INTERVENTIONS: None. MAIN OUTCOME MEASURES: The prevalence of the co-occurrence of congenital renal abnormalities in women with MDAs. RESULTS: Renal status was recorded in 186 of 255 women (72.9%), and the other women (27.1%) did not have a retrievable renal status. Congenital renal abnormalities were present in 90 of 186 women (48.4%) and were observed most frequently in women having a duplex uterus with obstructed hemivagina. The most common renal abnormality was unilateral renal agenesis, which was observed in 58 of 90 women (64.4%). CONCLUSIONS: MDAs are highly associated with different congenital renal abnormalities, and these results emphasize that women with MDAs should be routinely screened for their co-occurrence. However, these results also highlight that there remains a lack of awareness of this association. Whether all women with congenital renal abnormalities should be routinely screened for MDAs requires further investigation.

Age-Related Variation in Sympathetic Nerve Distribution in the Human Spleen.

Introduction: The cholinergic anti-inflammatory pathway (CAIP) has been proposed as an efferent neural pathway dampening the systemic inflammatory response via the spleen. The CAIP activates the splenic neural plexus and a subsequent series of intrasplenic events, which at least require a close association between sympathetic nerves and T cells. Knowledge on this pathway has mostly been derived from rodent studies and only scarce information is available on the innervation of the human spleen. This study aimed to investigate the sympathetic innervation of different structures of the human spleen, the topographical association of nerves with T cells and age-related variations in nerve distribution. Materials and Methods: Spleen samples were retrieved from a diagnostic archive and were allocated to three age groups; neonates, 10-25 and 25-70 years of age. Sympathetic nerves and T cells were identified by immunohistochemistry for tyrosine hydroxylase (TH) and the membrane marker CD3, respectively. The overall presence of sympathetic nerves and T cells was semi-automatically quantified and expressed as total area percentage. A predefined scoring system was used to analyze the distribution of nerves within different splenic structures. Results: Sympathetic nerves were observed in all spleens and their number appeared to slightly increase from birth to adulthood and to decrease afterward. Irrespective to age, more than halve of the periarteriolar lymphatic sheaths (PALSs) contained sympathetic nerves in close association with T cells. Furthermore, discrete sympathetic nerves were observed in the capsule, trabeculae and red pulp and comparable to the total amount of sympathetic nerves, showed a tendency to decrease with age. No correlation was found between the number of T cells and sympathetic nerves. Conclusion: The presence of discrete sympathetic nerves in the splenic parenchyma, capsule and trabecular of human spleens could suggest a role in functions other than vasoregulation. In the PALS, sympathetic nerves were observed to be in proximity to T cells and is suggestive for the existence of the CAIP in humans. Since sympathetic nerve distribution shows interspecies and age-related variation, and our general understanding of the relative and spatial contribution of splenic innervation in immune regulation is incomplete, it remains difficult to estimate the anti-inflammatory potential of targeting splenic nerves in patients.

Morphological hallmarks facilitating distinction of omental milky spots and lymph nodes: an exploratory study on their discriminative capacity.

BACKGROUND: Omental milky spots (OMSs) are the primary lymphoid structures of the greater omentum. However, the presence of lymph nodes (LNs) has occasionally been mentioned as well. Understanding which lymphoid structures are present is of significance, especially in gastric tumor metastasis; tumor deposits in omental LNs suggest local lymphatic spread, whereas tumor deposits in OMSs suggest peritoneal spread and hence extensive disease. Since LNs and OMSs share morphological characteristics and OMSs might be wrongly identified as LNs, reliable hallmarks facilitating easy discrimination are needed. MATERIALS AND METHOD: A series of microscopic morphological hallmarks unique to LNs were selected as potential candidates and were assessed for their discriminative capacity: 1) capsule, 2) trabeculae, 3) subcapsular sinus, 4) afferent lymphatic vessels, 5) distinct B- and T cell regions, and 6) a layered organization with, from the outside in a capsule, cortex, paracortex, and medulla. These hallmarks were visualized by multiple staining techniques. RESULTS: Hallmarks 1, 2 5 and 6 were shown to be the most efficient as these were consistent and discriminative. They were best visualized by Picrosirius red, smooth muscle actin and a B-cell / T-cell double staining. CONCLUSION: The presence of a capsule, trabeculae, distinct B- and T-cell regions and a layered organization represent consistent and reliable morphological features which allow to easily distinguish LNs from OMSs, especially when applied in combination.

A parapagus dicephalus tripus tribrachius conjoined twin with a unique morphological pattern: a case report.

BACKGROUND: Conjoined twinning is a rare congenital malformation with an incidence of about 1.5 per 100,000 births. Because no consensus has been reached regarding the dysmorphology, thorough descriptions of conjoined twins as part of teratological collections can be useful to increase knowledge of this congenital malformation. In this case report, we describe a parapagus dicephalus twin from the collection of the Department of Anatomy of the University Medical Center Utrecht in the Netherlands. External anatomical characteristics were assessed through a detailed macroscopic examination and internal characteristics by means of whole-body computed tomography and magnetic resonance imaging (3 Tesla). CASE PRESENTATION: Macroscopic examination showed a Caucasian male parapagus dicephalus tripus tribrachius conjoined twin a type of conjoined twinning in which there are two heads side by side, one rump, and three upper and three lower limbs. In addition, anencephaly was observed in the left twin. Radiological imaging showed a normal central nervous system in the right twin and absence of the calvaria, cerebrum, diencephalon, and mesencephalon in the left twin. There was clear duplication of the vertebral column, rib cage, respiratory system, and gastrointestinal system at least up to and including the first part of the duodenum. The heart consisted of a monoatrium with two separate ventricles. There was a fused liver with a single gallbladder, a single spleen, three kidneys, two bladders, and duplication of the penis. The third upper and lower extremities were articulating with a fused glenoid and acetabulum, respectively. The third foot showed both polydactyly and syndactyly of the toes. CONCLUSION: This case report describes a unique case of a male dicephalus parapagus tripus tribrachus conjoined twin discordant for anencephaly. Radiological imaging proved to be an adequate noninvasive method to provide insights into the internal (dys)morphology of this specific specimen, improving its scientific and educational value. This approach could be generally applied to other teratological specimens, thereby strengthening arguments regarding pathogenetic hypotheses, which may lead to new or improved insights into both normal and abnormal embryonic development.

Brain penetration of synthetic adenosine A1 receptor agonists in situ: role of the rENT1 nucleoside transporter and binding to blood constituents.

The blood-brain barrier (BBB) transport of synthetic A(1) receptor agonists was studied in an in situ brain perfusion model in the presence and absence of the selective nucleoside transport inhibitor S-(4-nitrobenzyl)-6-thioinosine (NBTI). For 8-methylamino-N(6)cyclopentyladenosine (MCPA), N(6)-cyclopentyladenosine (CPA), 2'deoxy-N(6)-cyclopentyladenosine (2'dCPA) and 5'deoxy-N(6)-cyclopentyl adenosine (5'dCPA) the brain uptake clearance was low with values of 0.0045+/-0.0012, 0.018+/-0.0020, 0.022+/-0.0028 and 0.12+/-0.054 ml min(-1)g(-1), respectively. In the presence of an average NBTI plasma concentration of 2.6+/-0.3 microg ml(-1) (NBTI dose: 3 mg kg(-1) i.v.) the values of the brain uptake clearance were 0.0062+/-0.0012, 0.013+/-0.0017, 0.014+/-0.0030 and 0.13+/-0.066 ml min(-1)g(-1), respectively and not significantly different from the values in the absence of NBTI. In a separate experiment the brain uptake of MCPA from phosphate buffered saline (PBS) and whole blood were compared. The brain uptake clearance from whole blood (0.0012+/-0.001 ml min(-1)g(-1)) was significantly lower than from PBS (0.0045+/-0.0012 ml min(-1)g(-1)). The results of these studies show that the rENT1 nucleoside transporter does not contribute significantly to the transport of synthetic A(1) receptor agonists across the BBB and that binding to blood constituents restricts the brain uptake.