Bone Marrow, Blood Cells, and the Lymphoid/Lymphatic System

Bone Marrow and Peripheral Blood Mononuclear Cell Phenotype Changes after Cultivation and Autologous Infusion in Patients with Primary Biliary Cholangitis

Background

Primary biliary cholangitis (PBC) is a condition affecting the liver and immune system. In this study, the impact of autologous bone marrow-derived mononuclear cell (BM-MNC) transplantation on PBC patients was investigated.

Methods

Sixteen eligible PBC patients participated at the National Scientific Medical Center in Astana, Kazakhstan, between 2017 and 2022, and BM-MNCs were harvested from their anterior iliac crest. After isolating and cultivating the BM-MNCs, they were infused back into the patient's peripheral veins. Changes in BM-MNC and peripheral blood mononuclear cell (PB-MNC) phenotypes were assessed before and after a 24-hour cultivation period and 72 hours post-transplantation. We monitored liver function parameters over 6-month intervals and conducted flow cytometry analysis to assess CD markers on BM-MNCs before and after cultivation and PB-MNCs before and after transplantation. Statistical analysis included the Friedman test for liver parameters and the Wilcoxon signed-rank test for BM-MNC and PB-MNC comparisons.

Results

Our findings revealed significant reductions in liver function tests after multiple transplantations. Flow cytometry analysis before and after a 24-hour culture and autologous BM-MNC infusion revealed the expansion of specific cell populations, with significant increases in CD3+, CD4+, CD16+, CD20+, CD25+, CD34+, CD105+, CD73+, СD117+, and CD34+populations, while CD4+25+, CD34+105+, and CD4+FOXP3+ populations decreased. Interestingly, a contradictory finding was observed with a decrease in bone marrow CD34+105+ cell lines (P=0.03) alongside an increase in peripheral CD34+105+ population (P=0.03).

Conclusion

In summary, our study shows that BM-MNC transplantation in PBC patients leads to changes in immune cell populations and liver function. These findings suggest potential therapeutic applications of BM-MNC transplantation in managing PBC and offer insights into the dynamics of immune cells associated with this treatment approach.

Linking bone marrow fat with decreased bone mineral density among Indian patients with osteoporotic fracture

Osteoporosis is a systemic skeletal disorder with low-bone mass causing micro-architectural deterioration and an increase in bone fragility and susceptibility to fractures. According to a worldwide report by IOF, 1 in 3 females and 1 in 5 males will experience fractures due to the osteoporotic changes in their bones. Fractures may be the first clinical manifestation of the disease. They have been causes for morbidity and mortality imposing economic burden to osteoporosis. Bone marrow fat is a negative regulator of bone-turnover and a key integrator of bone and energy metabolism. Hence we assess the bone marrow fat and BMD in patients with osteoporotic bone fractures. This cross-sectional study was conducted in 30 patients from the department of orthopaedic surgery. Biopsy samples were received from excised bone during surgery. Biochemical parameters and bone marrow fat were quantified by established methods. A negative correlation between BMD versus serum adiponectin, FGF21 and similar observation with BMD versus bone marrow fat is seen. Therefore, increased bone-marrow fat and adiponectin, FGF21 levels and decreased BMD in osteoporosis. This observation might be useful for prevention, management and therapeutic potential of osteoporosis. Based on our study findings, understand the bone-fat relationship to implications with low BMD in patients with osteoporosis.

Influence of Maternal BLV Infection on miRNA and tRF Expression in Calves

Small non-coding RNAs, such as microRNAs (miRNA) and tRNA-derived fragments (tRF), are known to be involved in post-transcriptional gene regulation. Research has provided evidence that small RNAs may influence immune development in calves. Bovine leukosis is a disease in cattle caused by Bovine Leukemia Virus (BLV) that leads to increased susceptibility to opportunistic pathogens. No research has addressed the potential influence that a maternal BLV infection may have on gene regulation through the differential expression of miRNAs or tRFs in progeny. Blood samples from 14-day old Holstein calves born to BLV-infected dams were collected. Antibodies for BLV were assessed using ELISA and levels of BLV provirus were assessed using qPCR. Total RNA was extracted from whole blood samples for small RNA sequencing. Five miRNAs (bta-miR-1, bta-miR-206, bta-miR-133a, bta-miR-133b, and bta-miR-2450d) and five tRFs (tRF-36-8JZ8RN58X2NF79E, tRF-20-0PF05B2I, tRF-27-W4R951KHZKK, tRF-22-S3M8309NF, and tRF-26-M87SFR2W9J0) were dysregulated in calves born to BLV-infected dams. The miRNAs appear to be involved in the gene regulation of immunological responses and muscle development. The tRF subtypes and parental tRNA profiles in calves born to infected dams appear to be consistent with previous publications in adult cattle with BLV infection. These findings offer insight into how maternal BLV infection status may impact the development of offspring.

High starch diets attenuate the immune function of Micropterus salmoides immune organs by modulating Keap1/Nrf2 and MAPK signaling pathways

Based on their good physiological functions and physical properties, carbohydrates are widely used in fish feed. However, excessive use of carbohydrates such as starch in fish feed may reduce the immunity of the fish and cause a series of health problems. In order to more clearly clarify the effects of different starch levels in feed on the immune organs of Micropterus salmoides, this study took the immune organs as the entry point and explored it from several perspectives, including differences in enzyme activity in plasma, changes in gene expression in immune organs, and resistance to pathogenic bacteria. The results showed that (1) high starch feed activates inflammatory responses in the spleen and head kidney through the MAPK signaling pathway. This leads to a decrease in the number of lymphocytes and weakens the resistance to pathogens; (2) high starch diet affects the antioxidant capacity of the trunk kidney by regulating the Keap1/Nrf2 pathway; (3) There was a strong correlation between gene expression patterns in the head kidney and lysozyme content in plasma. This implies that the high starch diet may regulate lysozyme production by affecting gene expression in the head kidney and further affect immune function. This study helps to reveal the interaction between starch and the immune system and provide scientific basis for the development of reasonable dietary recommendations and disease prevention.

An Intelligent Attention-Based Transfer Learning Model for Accurate Differentiation of Bone Marrow Stains to Diagnose Hematological Disorder

Bone marrow (BM) is an essential part of the hematopoietic system, which generates all of the body's blood cells and maintains the body's overall health and immune system. The classification of bone marrow cells is pivotal in both clinical and research settings because many hematological diseases, such as leukemia, myelodysplastic syndromes, and anemias, are diagnosed based on specific abnormalities in the number, type, or morphology of bone marrow cells. There is a requirement for developing a robust deep-learning algorithm to diagnose bone marrow cells to keep a close check on them. This study proposes a framework for categorizing bone marrow cells into seven classes. In the proposed framework, five transfer learning models-DenseNet121, EfficientNetB5, ResNet50, Xception, and MobileNetV2-are implemented into the bone marrow dataset to classify them into seven classes. The best-performing DenseNet121 model was fine-tuned by adding one batch-normalization layer, one dropout layer, and two dense layers. The proposed fine-tuned DenseNet121 model was optimized using several optimizers, such as AdaGrad, AdaDelta, Adamax, RMSprop, and SGD, along with different batch sizes of 16, 32, 64, and 128. The fine-tuned DenseNet121 model was integrated with an attention mechanism to improve its performance by allowing the model to focus on the most relevant features or regions of the image, which can be particularly beneficial in medical imaging, where certain regions might have critical diagnostic information. The proposed fine-tuned and integrated DenseNet121 achieved the highest accuracy, with a training success rate of 99.97% and a testing success rate of 97.01%. The key hyperparameters, such as batch size, number of epochs, and different optimizers, were all considered for optimizing these pre-trained models to select the best model. This study will help in medical research to effectively classify the BM cells to prevent diseases like leukemia.

Bone Marrow Changes in Septic Shock: A Comprehensive Review

Septic shock is a life-threatening condition characterized by systemic inflammation resulting from a severe infection. Although the primary focus of sepsis research has traditionally been on the dysfunctional immune response, recent studies have highlighted the important role of bone marrow in the pathophysiology of septic shock. The bone marrow, traditionally regarded as the hematopoietic organ responsible for blood cell production, undergoes significant changes during sepsis, contributing to the overall immune dysregulation observed in this condition. This comprehensive review aims to provide a detailed overview of the bone marrow changes associated with septic shock. It explores the alterations in the bone marrow microenvironment, hematopoietic progenitor cells, and the subsequent effects on leukocyte production and function. Key cellular and molecular mechanisms involved in bone marrow dysfunction during septic shock are discussed, including the dysregulation of cytokines, chemokines, growth factors, and signaling pathways. Furthermore, this review highlights the clinical implications of bone marrow changes in septic shock. It emphasizes the impact of altered hematopoiesis on immune cell populations, such as neutrophils, monocytes, and lymphocytes, and their role in the progression and outcome of sepsis. The potential prognostic value of bone marrow parameters and the therapeutic implications of targeting bone marrow dysfunction are also addressed. The review summarizes relevant preclinical and clinical studies to comprehensively understand the current knowledge of bone marrow changes in septic shock. The limitations and challenges of studying bone marrow in the context of sepsis are acknowledged, and future directions for research are proposed.

Haematology, biochemistry and morphological features of peripheral blood cells in captive Boa constrictor

The common boa (Boa constrictor) belongs to the family Boidae and represents one of the most popular traded and kept snake species in captivity. The early diagnosis, prevention and prophylaxis of diseases in this species, and in reptiles in general, still pose major challenges, also due to the lack of reliable reference values. This prompted us to conduct a study on clinically healthy captive B. constrictor to assess their basic health parameters in the blood (haematological and biochemical values, stress markers). Several parameters differed significantly between younger (<3 years) and older (≥3 years) boas; in the latter, the percentages of eosinophils, the haemoglobin and haematocrit levels, as well as the albumin and total protein levels, were higher. In male snakes, cholesterol levels were significantly higher than in females. Light and electron microscopy as well as immunohistochemistry served to identify and determine the morphological features of peripheral blood cells, that is, heterophils, basophils, eosinophils, azurophils, monocytes, lymphocytes, thrombocytes and erythrocytes. Leukocyte subpopulations, that is, T and B cells and monocytes, were also identified based on specific marker expression. The study provides data on haematological, biochemical and stress hormone levels, suitable as reference values, and on the blood cell morphology of B. constrictor which can serve as a guideline for further research on this species.

Automated Bone Marrow Cell Classification for Haematological Disease Diagnosis Using Siamese Neural Network

The critical structure and nature of different bone marrow cells which form a base in the diagnosis of haematological ailments requires a high-grade classification which is a very prolonged approach and accounts for human error if performed manually, even by field experts. Therefore, the aim of this research is to automate the process to study and accurately classify the structure of bone marrow cells which will help in the diagnosis of haematological ailments at a much faster and better rate. Various machine learning algorithms and models, such as CNN + SVM, CNN + XGB Boost and Siamese network, were trained and tested across a dataset of 170,000 expert-annotated cell images from 945 patients' bone marrow smears with haematological disorders. The metrics used for evaluation of this research are accuracy of model, precision and recall of all the different classes of cells. Based on these performance metrics the CNN + SVM, CNN + XGB, resulted in 32%, 28% accuracy, respectively, and therefore these models were discarded. Siamese neural resulted in 91% accuracy and 84% validation accuracy. Moreover, the weighted average recall values of the Siamese neural network were 92% for training and 91% for validation. Hence, the final results are based on Siamese neural network model as it was outperforming all the other algorithms used in this research.

Multiple Myeloma with Skin and Renal Involvement and Anaplasma Phagocytophilum Co-Infection in a Dog

An 11-year-old male Cocker Spaniel was presented with acute onset of apathy, polyuria and polydipsia. Blood examination showed hypoalbuminemia and hyperglobulinemia, while electrophoresis revealed monoclonal gammopathy. Subsequent tests showed glycosuria, proteinuria, a positive serology test for Anaplasma spp. and ultrasonographical changes of the liver and spleen. Urine electrophoresis confirmed the presence of Bence-Jones protein. The dog’s condition deteriorated, and the dog had developed skin lesions on the neck and body. The owner decided to euthanize the dog and agreed to bone marrow and skin biopsy. Bone marrow cytology revealed an increased number of plasma cells and several cellular atypia. Histopathology of the skin lesions showed a round cell tumor of lymphoid or plasmacytoid origin. Subsequent immunohistology supported the diagnosis of multiple myeloma cutaneous involvement.

This case report describes unusual features observed in a dog with multiple myeloma.

Method comparison for serum protein electrophoretic M-protein quantification: Agarose gel electrophoresis and capillary zone electrophoresis in canine and feline sera

BACKGROUND

Densitometric quantification of myeloma paraproteins (M-proteins) is used to monitor secretory myeloma related disorders in humans and dogs. The previous work in dogs used agarose gel electrophoresis (AGE) but did not establish if other methods of serum protein electrophoresis, such as capillary zone electrophoresis (CZE), were comparable.

OBJECTIVES

We aimed to determine if the densitometric quantification of M-proteins using CZE would yield results comparable to AGE methods.

METHODS

Fifty-one serum samples from 22 dogs and 18 cats with confirmed monoclonal gammopathies and previously performed AGE were evaluated using CZE on a Sebia Minicap system. Samples were run in duplicate, and their M-proteins were densitometrically measured using the corrected perpendicular drop method previously described. Human-based quality control samples were used to determine the inter-run coefficient of variation (CV). Patient samples were used to calculate the intra-run CV. Method comparison was performed using simple linear regression, Passing-Bablok regression, and Bland-Altman analyses, and Medx evaluations.

RESULTS

Inter-run and intra-run CVs for CZE were 3.71%-7.65% and 2.89%-4.74%, respectively. Simple linear regression demonstrated an excellent correlation (r > 0.98). Passing-Bablok regression was compatible with the presence of proportional bias in the entire population, and Bland-Altman plots revealed a proportional bias in the feline cases. The Medx evaluation suggested that the two methods did not perform similarly in clinical samples with poor performance at a decision limit of 0.5 gm/dL.

CONCLUSIONS

Capillary zone electrophoresis is an acceptable method for M-protein densitometric quantification in canine and feline sera but cannot be used interchangeably with AGE-based evaluations.

Splenomegaly development and disseminated intravascular coagulation syndrome in acute canine babesiosis

Disseminated intravascular coagulation (DIC) syndrome is the main defining process in the pathogenetic axis of complications in canine babesiosis. The involvement of the spleen with further irreversible changes in the organ largely determines the severity of the animal’s condition after spontaneous babesiosis. The work presented here aimed to determine the role of the DIC syndrome as a triggering factor for lesions of the spleen. Clinical and laboratory studies (haematological, biochemical, hemodynamic) have been carried out. Pathological studies of the removed spleen were carried out by histological methods using universal and specific staining. After suffering acute spontaneous babesiosis, the development of hypersplenism and splenomegaly was found in dogs. The diagnosis was confirmed haematologically by the detected cytopenia, normochromic type anaemia. An additional parameter was a significantly increased erythrocyte sedimentation rate. The biochemical profile indicated the development of bilirubinaemia due to the conjugated fraction, hyperfermentation of transaminases, hypoalbuminemia, which reflected the development of hepatitis and liver failure. Markers of DIC syndrome in laboratory studies are represented by reliable hypofibrinogenemia, increased level of fibrinogen/fibrin degradation products, including D-dimer, and soluble fibrin monomer complexes. The multidirectional indices of coagulation tests (activated partial thromboplastin and prothrombin time) made it possible to classify the stage of “consumption coagulopathy” of the DIC syndrome. The haemodynamic parameters of the sick dogs were characterized by a significant deficit in the circulating blood volume. Together with the indicators of the “consumption coagulopathy” stage of the DIC syndrome, the hemodynamic indexes indicate a moderate degree of shock stage II – the stable reversibility, but the magnitude of the circulating blood volume deficit determines the tendency towards shock irreversibility. Histological studies have established a significant proliferation of the stromal elements of the organ, the formation of specific complexes of vessels with sinuses, clogging with blood clots, and the organ's parenchyma dystrophy. Such changes characterize complete splenomegaly, which is based on the organo-pathology of the DIC syndrome. The deposition of “old” fibrin in the connective tissue structures of the spleen indicates that DIC syndrome continues throughout the entire period of hyperplastic changes in the organ. The presence of hyalinosis in blood vessel walls of the spleen parenchyma determines irreversible changes in them. Thus, DIC syndrome is the basis for splenomegaly development in dogs after acute spontaneous babesiosis. It is confirmed by laboratory blood tests and histologically by the presence of fibrin thrombi in the structures of the organ, which determine the organopathology of the syndrome. The information obtained serves to expand the concepts of the pathogenesis of blood protozoal disease, define the high risk of complications that can become fatal for the health and life of animals.

Hepatic lesions associated with iron accumulation in captive kori bustards (Ardeotis kori)

There are anecdotal reports of iron storage disease in captive kori bustards (Ardeotis kori), but detailed descriptions of this disease have not been reported. The goals of this retrospective, multi-institutional study were to (1) describe microscopic findings associated with iron accumulation in postmortem tissues of kori bustards and (2) use an adapted grading scale to score iron accumulation and associated hepatic lesions. Tissue sections from 19 adult captive kori bustards (age range 3-28 years; 12 males and 7 females) were evaluated histologically with hematoxylin and eosin, Masson's trichrome, and Prussian blue stains, and scored for iron accumulation. Hemochromatosis was diagnosed in cases with iron storage (in hepatocytes and/or Kupffer cells) and concurrent parenchymal damage (defined as having both necrosis and fibrosis). Hemosiderosis was diagnosed in animals with evidence of iron storage without necrosis or fibrosis. Ten of the 19 cases (age range 8-27 years; 7 males and 3 females) were diagnosed with hemochromatosis, including 6 with mild disease, 3 with moderate disease, and 1 with severe disease. Histologic evidence of iron accumulation was also identified in kidney, intestinal tract, adrenal gland, and spleen, but there were no associations between severity of iron accumulation in the liver and accumulation in other organs.

Coformulation with Tattoo Ink for Immunological Assessment of Vaccine Immunogenicity in the Draining Lymph Node

Characterization of germinal center B and T cell responses yields critical insights into vaccine immunogenicity. Nonhuman primates are a key preclinical animal model for human vaccine development, allowing both lymph node (LN) and circulating immune responses to be longitudinally sampled for correlates of vaccine efficacy. However, patterns of vaccine Ag drainage via the lymphatics after i.m. immunization can be stochastic, driving uneven deposition between lymphoid sites and between individual LN within larger clusters. To improve the accurate isolation of Ag-exposed LN during biopsies and necropsies, we developed and validated a method for coformulating candidate vaccines with tattoo ink in both mice and pigtail macaques. This method allowed for direct visual identification of vaccine-draining LN and evaluation of relevant Ag-specific B and T cell responses by flow cytometry. This approach is a significant advancement in improving the assessment of vaccine-induced immunity in highly relevant nonhuman primate models.

Porcine Babesiosis Caused by Babesia sp. Suis in a Pot-Bellied Pig in South Africa

Babesiosis is a worldwide, tick-borne disease of economic importance in livestock caused by Babesia spp., which are hemoparasitic piroplasms that target the host erythrocytes. Cattle, dogs, small ruminants, and wild ruminants are the species most commonly affected, while in cats, horses, and pigs, it is less frequently reported. Although babesiosis has been observed worldwide, porcine babesiosis remains an uncommon disease with a very limited number of cases reported. Here, we describe a case in a 12-year old pot-bellied pig from South Africa that died after a history of anorexia and reluctance to rise for 2 days. A complete necropsy, blood smear cytology, reverse line blot (RLB) hybridization and 18S rRNA sequencing were performed. Numerous Babesia spp. hemoparasites and a moderate regenerative anemia were identified on blood smear, and a urine dipstick test yielded 4+ heme. Diffuse icterus and splenomegaly were observed upon gross examination. Histopathology revealed hemoglobin casts within renal tubules and collecting ducts, pulmonary edema, splenic congestion, and intrahepatic cholestasis. BLASTN homology of the 18SrRNA sequence revealed a 100% identity to the published sequence of Babesia sp. Suis isolated from pigs in Italy. This case of babesiosis in a pig highlights the clinical manifestations and gross and pathological findings of porcine babesiosis.

Chlamydia pecorum-Induced Arthritis in Experimentally and Naturally Infected Sheep

Chlamydia pecorum is an obligate intracellular pathogen with a wide host range including livestock such as sheep, cattle, goats, and pigs as well as wildlife species such as koalas. Chlamydial polyarthritis is an economically important disease resulting in swollen joints, lameness, stiffness, and weight loss in young sheep. In the present study, tissues from sheep experimentally or naturally infected with Chlamydia pecorum were assessed by histopathology and immunohistochemistry. Carpal, hock, and stifle joints as well as spleen, liver, kidney, lymph nodes, lung, and brain of 35 sheep from different inoculation groups were available. Two different C. pecorum strains (IPA and E58), different routes of administration (intraarticular or intravenous), UVA-irradiated IPA strain, and corresponding noninfected control groups were investigated. Similar investigations on tissues from 5 naturally infected sheep were performed. The most obvious inflammatory lesions were observed in synovial tissues and, notably, in the renal pelvis from the experimentally infected group and naturally infected animals. This resulted in chronic or chronic-active arthritis and pyelitis. Intralesional chlamydial inclusions could be demonstrated by immunohistochemistry in both tissues. Immunohistochemical evaluation of the presence and distribution of macrophages, T and B cells in synovial tissues revealed macrophages as the most prevalent inflammatory cell population. Previous observations indicated that C. pecorum isolates can infect circulating monocytes. Together with the finding of the histological lesions in synovial tissues and internal organs alongside the presence of C. pecorum DNA, these observations suggest chlamydial arthritis in lambs is the result of hematogeneous spread of C. pecorum.

Review of clinical aspects, epidemiology and diagnosis of haemotropic Mycoplasma ovis in small ruminants: current status and future perspectives in tropics focusing on Malaysia

Mycoplasma ovis (formerly Eperythrozoon ovis) is an epierythrocytic parasitic bacterium of small ruminants known as haemotropic mycoplasma, which is transmitted mechanically by biting flies and contaminated instruments. Acute mycoplasmosis causes severe haemolytic anaemia and mortality in young animals. At the same time, chronic disease may produce mild anaemia and varying degrees of morbidity depending on several factors, including age, reproductive status, the plane of nutrition, immunological status and the presence of concurrent infection. Haemotropic Mycoplasma ovis is currently recognised as an emerging zoonotic pathogen which is widely distributed in the sheep and goat producing areas of tropics and subtropics, where the disease is nearly endemic. Human infection has been reported in pregnant women, immunocompromised patients and people exposed to animals and arthropods. The current diagnosis of haemoplasma relies on microscopic evaluation of Giemsa-stained blood smear and PCR. Although there are few published reports on the incidence of haemotropic Mycoplasma ovis infection of small ruminants in Malaysia, information on its prevalence, risk factors, severity and economic impacts is grossly inadequate. Therefore, a large-scale survey of small ruminant flocks is necessary to elucidate the current seroprevalence status and molecular characteristics of haemotropic M. ovis infection in Malaysia using ELISA and PCR sequencing technologies. In the future, surveillance programs, including vector forecast, quarantine, monitoring by periodic surveys and public enlightenment, will limit the internal and transboundary spread of M. ovis, enhance control efforts and mitigate production losses in Malaysia.

Otodectes cynotis (Sarcoptiformes: Psoroptidae): New Records on Wild Carnivores in Brazil With a Case Report

The genus Otodectes Canestrini 1894, comprises an unique species, Otodectes cynotis (Hering, 1838), that is responsible for the 'ear mange' in terrestrial carnivores worldwide. Here we report its occurrence in four Brazilian host species from the southeastern region, based on records from Carnivora in the Acari Collection of the Butantan Institute, São Paulo state (IBSP). We also register a case report of a crab-eating fox, Cerdocyon thous L. 1758 found parasitized by this mite species.

The spleen morphophysiology of fruit bats

Spleen is one of the important lymphoid organs with wide variations of morphological and physiological functions according to species. Morphology and function of the spleen in bats, which are hosts to several viral strains without exhibiting clinical symptoms, remain to be fully elucidated. This study aims to examine the spleen morphology of fruit bats associated with their physiological functions. Spleen histological observations were performed in three fruit bats species: Cynopterus titthaecheilus (n = 9), Rousettus leschenaultii (n = 3) and Pteropus vampyrus (n = 3). The spleens of these fruit bats were surrounded by a thin capsule. Red pulp consisted of splenic cord and wide vascular space filled with blood. Ellipsoids in all three studied species were found numerously and adjacent to one another forming macrophages aggregates. White pulp consisted of periarteriolar lymphoid sheaths (PALS), lymphoid follicles and marginal zone. The lymphoid follicle contained a germinal centre and a tingible body macrophage that might reflect an active immune system. The marginal zone was prominent and well developed. This study reports some differences in spleen structure of fruit bats compared to other bat species previously reported and discusses possible physiological implications of the spleen based on its morphology.