Changes in expression levels of Nod-like receptors in the spleen of ewes

Nucleotide-binding oligomerization domain receptors (NOD-like receptors, NLRs) have critical effects on interfaces of the immune and reproductive systems, and the spleen plays a key role in both innate and adaptive immune functions. It is hypothesized that NLR family participates in maternal splenic immune regulation during early pregnancy in sheep. In this study, maternal spleens were collected on day 16 of the estrous cycle, and days 13, 16 and 25 of gestation (n = 6 for each group) in ewes. Expression of NLR family, including NOD1, NOD2, class II transactivator (CIITA), NLR family apoptosis inhibitory protein (NAIP), nucleotide-binding oligomerization domain, Leucine rich repeat and Pyrin domain containing 1 (NLRP1), NLRP3 and NLRP7, was analyzed using quantitative real-time PCR, Western blot and immunohistochemistry analysis. The results revealed that expression levels of NOD1, NOD2, CIITA and NLRP3 were downregulated at days 13 and 16 of pregnancy, but expression of NLRP3 was increased at day 25 of pregnancy. In addition, expression values of NAIP and NLRP7 mRNA and proteins were improved at days 16 and 25 of pregnancy, and NLRP1 was peaked at days 13 and 16 of pregnancy in the maternal spleen. Furthermore, NOD2 and NLRP7 proteins were limited to the capsule, trabeculae and splenic cords. In summary, early pregnancy changes expression of NLR family in the maternal spleen, which may be related with the maternal splenic immunomodulation during early pregnancy in sheep.(AU)

Postvaccinal pyogranulomas in cattle

Clinical History: The carcasses of seven 30-month-old female cows slaughtered in a local abattoir for meat production were totally condemned during meat inspection due to disseminated gross abnormalities. Gross findings: On internal examination, several skeletal muscles (pectoralis superficialis and profundus, transversus abdominis, diaphragm, obliquus internus abdominis, and rectus abdominis) and random areas of the peritoneal cavity had multifocal to coalescing nodules (1-3 cm in diameter). The nodules were firmly adhered (fibrous adherences) to the adjacent tissues and surface of portions of the forestomach serosa and splenic capsule. On the cut surface of the nodules, there was a central accumulation of a friable and yellow exudate surrounded by a fibrous capsule. No external lesions were seen in any of the cows.(AU)

Early pregnancy affects expression of Toll-like receptor signaling members in ovine spleen

Abstract Toll-like receptors (TLRs) are involved to the maternal immune tolerance. The spleen is essential for adaptive immune reactions. However, it is unclear that early pregnancy regulates TLR-mediated signalings in the maternal spleen. The purpose of this study was to investigate the effects of early pregnancy on expression of TLR signaling members in the ovine spleen. Ovine spleens were collected at day 16 of the estrous cycle, and at days 13, 16 and 25 of pregnancy (n = 6 for each group). Real-time quantitative PCR, western blot and immunohistochemistry analysis were used to detect TLR signaling members, including TLR2, TLR3, TLR4, TLR5, TLR7, TLR9, myeloid differentiation primary-response protein 88 (MyD88), tumor necrosis factor receptor associated factor 6 (TRAF6) and interleukin-1-receptor-associated kinase 1 (IRAK1). The results showed that expression levels of TLR2, TLR4 and IRAK1 were downregulated, but expression levels of TLR3, TLR5, TLR7, TLR9, TRAF6 and MyD88 were increased during early pregnancy. In addition, MyD88 protein was located in the capsule, trabeculae and splenic cords of the maternal spleen. This paper reports for the first time that early pregnancy has effects on TLR signaling pathways in the ovine spleen, which is beneficial for understanding the maternal immune tolerance during early pregnancy.

Vagotomy associated with splenectomy reduces lipid accumulation and causes kidneys histological changes in rats with hypothalamic obesity

Purpose To evaluate the influence of autonomic vagal and splenic activities on renal histomorphometric aspects in obese rats. Methods Thirty male Wistar rats were used, of which, 24 received subcutaneous injections of monosodium glutamate (MSG) during the first 5 days of life (4 g/kg body weight) and six control animals received injections of saline solution (CON). Five experimental groups were organized (n = 6/group): falsely-operated control (CON-FO); falsely-operated obese (MSG-FO); vagotomized obese (MSG-VAG); splenectomized obese (MSG-SPL); vagotomized and splenectomized obese (MSG-VAG-SPL). Results The MSG-FO group animals showed a significant reduction in body weight and nasal-anal length when compared to CON-FO group animals (p 0.05). The MSG-VAG-SPL group showed significant reduced in most biometric parameters associated with obesity. Falsely-operated obese animals showed a significant reduction in renal weight, glomerular diameters, glomerular tuff and capsule areas and Bowmans space compared to CON-FO group animals (p < 0.05). There was a significant reduction in diameter, glomerular tuft and capsule areas, and Bowmans space in MSG-VAG, MSG-SPL, MSG-VAG-SPL groups when compared to the MSG-FO group. Conclusions Vagotomy associated with splenectomy induces a reduction in the adiposity and causes histological changes in the kidney of obese rats.(AU)

Early pregnancy affects expression of Toll-like receptor signaling members in ovine spleen

Toll-like receptors (TLRs) are involved to the maternal immune tolerance. The spleen is essential for adaptive immune reactions. However, it is unclear that early pregnancy regulates TLR-mediated signalings in the maternal spleen. The purpose of this study was to investigate the effects of early pregnancy on expression of TLR signaling members in the ovine spleen. Ovine spleens were collected at day 16 of the estrous cycle, and at days 13, 16 and 25 of pregnancy (n = 6 for each group). Real-time quantitative PCR, western blot and immunohistochemistry analysis were used to detect TLR signaling members, including TLR2, TLR3, TLR4, TLR5, TLR7, TLR9, myeloid differentiation primary-response protein 88 (MyD88), tumor necrosis factor receptor associated factor 6 (TRAF6) and interleukin-1-receptor-associated kinase 1 (IRAK1). The results showed that expression levels of TLR2, TLR4 and IRAK1 were downregulated, but expression levels of TLR3, TLR5, TLR7, TLR9, TRAF6 and MyD88 were increased during early pregnancy. In addition, MyD88 protein was located in the capsule, trabeculae and splenic cords of the maternal spleen. This paper reports for the first time that early pregnancy has effects on TLR signaling pathways in the ovine spleen, which is beneficial for understanding the maternal immune tolerance during early pregnancy.(AU)

Morfologia e topografia do baço da paca ( Cuniculus paca Linnaeus, 1766) / Morphology and topography of the spleen of paca ( Cuniculus paca )

A paca é um grande roedor, presente em parte do território brasileiro e na América Latina, cuja importância está na crescente produção comercial de carne exótica e na pesquisa científica como um promissor modelo experimental. Assim, este trabalho objetivou-se descrever a morfologia e a topografia do baço da paca (Cuniculus paca). Foram utilizadas cinco pacas adultas, machos e fêmeas, fixadas em formaldeído a 10% e armazenados em solução salina a 30% para sua conservação. Na paca, o baço tem sua localização relacionada ao estômago, ao fígado, ao rim esquerdo, ao pâncreas e ao omento maior. Possui forma irregular, sendo mais longo do que largo, possui coloração avermelhada-escura e textura lisa. Quanto à descrição histológica, apresenta cápsula de tecido conjuntivo denso que emitiu trabéculas que se projetam no parênquima. A cápsula e as trabéculas apresentam fibras musculares lisas. O parênquima è composto pela polpa branca e polpa vermelha, esta última formada por seios e cordões esplênicos.(AU)

Paca is a large rodent, distributed in part of the Brazilian territory and in Latin America, whose importance is related to the crescent commercial production of exotic meat and in scientific research as a promising experimental model. The morphology and topography of the spleen of paca (Cuniculus paca) is described. Five adult pacas, male and female, were fixed with formaldehyde 10% and stored in 30% saline solution for preservation. The spleen of paca has the anatomical position related to stomach, liver, left kidney, pancreas and greater omentum. The spleenis irregular, longer than larger, with reddish-dark color and smooth texture. Related to the histological description, the spleen has capsule of dense connective tissue that emitted trabeculae projecting into the parenchyma. The capsule and trabeculae has smooth muscle fibers. The parenchyma is composed by the white and red pulp, the latter composed with sinusoids and splenic cords.(AU)

Morfologia e topografia do baço da paca (Cuniculus paca Linnaeus, 1766) / Morphology and topography of the spleen of paca (Cuniculus paca)

A paca é um grande roedor, presente em parte do território brasileiro e na América Latina, cuja importância está na crescente produção comercial de carne exótica e na pesquisa científica como um promissor modelo experimental. Assim, este trabalho objetivou-se descrever a morfologia e a topografia do baço da paca (Cuniculus paca). Foram utilizadas cinco pacas adultas, machos e fêmeas, fixadas em formaldeído a 10% e armazenados em solução salina a 30% para sua conservação. Na paca, o baço tem sua localização relacionada ao estômago, ao fígado, ao rim esquerdo, ao pâncreas e ao omento maior. Possui forma irregular, sendo mais longo do que largo, possui coloração avermelhada-escura e textura lisa. Quanto à descrição histológica, apresenta cápsula de tecido conjuntivo denso que emitiu trabéculas que se projetam no parênquima. A cápsula e as trabéculas apresentam fibras musculares lisas. O parênquima è composto pela polpa branca e polpa vermelha, esta última formada por seios e cordões esplênicos.(AU)

Paca is a large rodent, distributed in part of the Brazilian territory and in Latin America, whose importance is related to the crescent commercial production of exotic meat and in scientific research as a promising experimental model. The morphology and topography of the spleen of paca (Cuniculus paca) is described. Five adult pacas, male and female, were fixed with formaldehyde 10% and stored in 30% saline solution for preservation. The spleen of paca has the anatomical position related to stomach, liver, left kidney, pancreas and greater omentum. The spleenis irregular, longer than larger, with reddish-dark color and smooth texture. Related to the histological description, the spleen has capsule of dense connective tissue that emitted trabeculae projecting into the parenchyma. The capsule and trabeculae has smooth muscle fibers. The parenchyma is composed by the white and red pulp, the latter composed with sinusoids and splenic cords.(AU)

Canine visceral leishmaniasis: structural and immune-inflammatory changes in lymphoid organs of naturally infected dogs

Background: Although the canine visceral leishmaniasis be characterized as a severe systemic disease, few studies have been conducted describing the main histopathological alterations found in the various organs of the host affected by the parasite. This paper evaluated the structural and immune-inflammatory changes of the spleen, liver, popliteal lymph nodes (PLN) and skin of naturally infected dogs in different clinical forms of canine visceral leishmaniasis. Material, Methods & Results: Forty seven adult dogs were used, varying in age and weight, selected by Immunofluorescence Assay (IFA), were considered positive IFA titres of ≥ 1:40 and the parasitological examination of L. infantum amastigotes forms in bone marrow smears. The dogs were grouped according to the clinical signs associated to the disease: negative dogs (ND = 7), subclinical dogs (SD = 20) and clinical dogs (CD = 20). After the euthanasia procedure, all animals were weighed, and then the spleen and liver were dissected for relative weights measurements. Fragments of spleen, liver, PLN and skin were collected and subjected to procedures for histology (H&E). The same samples were subjected to immunohistochemical analysis for detection of L. infantum amastigotes. The authors observed increased relative weight of spleen and liver of the CD and SD groups (P < 0.05). Discrete hypoplasia of red and white pulps and capsular thickening, moderate hypertrophy of red and white pulps and intense splenic congestion were observed in the spleen in group SD, whereas a slight thickening of the capsule and hypertrophy of red and white pulps, intense congestion and moderate subcapsular fibrosis and hypoplasia of the splenic red and white pulps were found in the CD group. Histological evaluation of the liver showed moderate periportal inflammatory infiltrate, hypertrophy/hyperplasia of Kupffer cells and congestion, slight thickening of the capsule and intralobular granulomas in the SD group, while moderate peri-portal inflammatory infiltrate, hypertrophy/hyperplasia of Kupffer cells, congestion, thickening of the capsule and intralobular granulomas were found in the CD group. The PLN histologic evaluation presented discrete capsular inflammation, congestion, hemosiderosis and hypertrophy/hyperplasia of lymphatic nodules and moderate hypertrophy/hyperplasia of cortical and medullar in the SD group, while slight capsular inflammation, congestion, hemosiderosis and hypertrophy/hyperplasia of lymphatic nodules and moderate hypertrophy/hyperplasia of cortical and medullar were found in the CD group. The main change observed in the skin was moderate histiolymphocyte inflammatory infiltrate in the SD group. The greatest parasite density of L. infantum amastigotes could be observed in the spleen. Discussion: The capsular thickening, subcapsular fi brosis and hypoplastic spleen can be explained by the disease chronicity. The liver infection caused by L. infantum has the ability to self-resolute through an immune response mediated by Th1 lymphocytes, mono-nuclear cells and involving the Kupffer cells, macrophages and subsequent granuloma formation. The hypertrophy/hyperplasia of cortical and medullary in lymph nodes is considered the most relevant change, because they suggest that the immunopathological status is a characteristic of chronic infection. In dogs infected by L. infantum, the ears are the skin areas where the lesions and inflammatory infiltrates are most evident. This unequal tropism doesn't occurs solely because of the area being the preferred location by transmitting insects, but also by the high incidence of lesions caused by ectoparasites and itchy reactions. It follows that organs and tissues of dogs naturally infected by L. infantum have histological changes consistent with immune-inflammatory response, demonstrating the functional impairment of the same.

Estabelecimento e implementação de protocolo de hematotoxicidade para utilização em ensaios pré-clínicos de medicamentos: estudo em ratos

O objetivo do presente estudo foi o de investigar, pela primeira vez: os efeitos da administração prolongada de sementes Senna occidentalis (S. occidentalis) em órgãos hematopoiéticos de ratos, utilizando metodologias que poderão ser sugeridas para estudo pré-clínico de medicamentos. Avaliou-se nestes animais: consumo de ração e água; peso médio semanal; parâmetros hematológicos e bioquímicos; padrões histopatológicos; estoque de ferro e ensaios clonogênicos. O estudo foi realizado em ratos Wistar machos de 90 dias de idade, os quais foram expostos a diferentes concentrações de S. occidentalis na ração, a saber: 0% (controle), 0,5% (So0,5%), 1% (So1%) e 2% (So2%) durante 90 dias. Foi importante incluir um grupo pair-fed (PF), o qual recebeu a mesma quantidade de ração consumida pelo grupo So2%, porém, isenta da planta, uma vez que a S. occidentalis é sabidamente anorexígena. O presente estudo demonstrou que os ratos do grupo So2% apresentaram diminuição no número de leucócitos totais bem como alterações nos parâmetros referentes a série vermelha, tais como diminuição do VCM e HCM, caracterizando uma anemia microcítica hipocrômica. Os dados do hemograma corroboram as alterações observadas no mielograma destes animais, uma vez que foi constatada a redução significante da relação Mielóide/Eritróide (M/E) e, portanto, um possível efeito tóxico da S. occidentalis sobre a medula óssea durante o tratamento de 90 dias. A redução significante da relação M/E nos animais pertencentes aos diferentes grupos experimentais ocorreu devido ao aumento progressivo de eritroblastos jovens e policromáticos na medula óssea destes animais. Índices baixos da relação M/E podem estar associados a uma anemia regenerativa em função de hemólise extravascular ou, ainda, à eritropoiese ineficaz. A partir do mielograma observou-se, também, redução significante de células blásticas e de todos os tipos celulares, especialmente, da linhagem granulocítica, com predomínio da linhagem linfocitária. No entanto, uma vez que os linfócitos estão, continuadamente, recirculando, o aumento ou a diminuição destas células não reflete, necessariamente, alteração na linfopoiese. A análise anatomopatológica da medula óssea de animais dos grupos experimentais apontou um aumento progressivo da celularidade, caracterizando hiperplasia medular. Estes resultados se correlacionam aos dados do mielograma. Na anemia regenerativa ocorre diminuição da sobrevida das hemácias na circulação, resultante de hemólise extravascular realizada por macrófagos, especialmente, do tecido esplênico. Assim, o tratamento prolongado com S. occidentalis poderia estar associado ao um processo hemolítico, haja vista a observação de aumento do peso relativo deste órgão; acúmulo de hemossiderina no baço e ainda, reticulocitose em animais tratados com esta planta. O tratamento de 90 dias com S. occidentalis promoveu, também, redução significante na celularidade do baço bem como alterações anatomopatológicas, incluindo espessamento de cápsula e rarefação celular. Os ensaios clonogênicos padronizados neste estudo apontaram redução da porcentagem de colônias BFU-E e CFU-E em animais do grupo So2%, indicando uma provável ação tóxica da S.occidentalis sobre os progenitores medulares. A partir dos dados apresentados no presente estudo, pode-se concluir que o tratamento por 90 dias com S. occidentalis na ração é hematotóxico. Além disto, os resultados aqui obtidos bem como as metodologias empregadas poderão contribuir para o estabelecimento de um protocolo de hematotoxicidade, haja vista que informações relacionadas aso mecanismos de hematopoiese; metabolismo de ferro; características histológicas e citológicas de órgãos hematopoiéticos (baço e medula óssea) de ratos foram levadas em consideração para a realização deste estudo.

The purpose of this study was to investigate, for the first time: the effects of long term administration of Senna occidentalis (S. occidentalis) seeds in hematopoietic organs of rats, using methodology that can be suggested for pre-clinical studies. We evaluated some parameters in these animals: feed intake and water; weight body; hematological and biochemical parameters; histopathology; iron stores and clonogenic assays. The study was conducted in 90-day-old male Wistar rats, which were exposed to different concentrations of S. occidentalis in feed, ie: 0% (control), 0.5% (So0.5%), 1% (So1%) and 2 % (So2%) for 90 days. It was important to include a pair-fed group (PF), which received the same amount of feed consumed by So2% group, however, without the plant, once S. occidentalis is known anorectic. This study showed that rats from So2% group presented a decrease in the number of total leukocytes as well as changes in the parameters for the red series, such as decrease in MCV and MCH values, featuring a hypochromic anemia. The blood count results corroborate the findings from bone marrow smears of these animals, since it was found the significant reduction ratio Myeloid / Erythroid (M / L) and, therefore, a possible toxic effect of the S. occidentalis on the bone marrow during the treatment of 90 days. The significant reduction in the ratio M / E in animals belonging to different experimental groups occurred due to the progressive increase of young and polychromatic erythrocytes in the bone marrow of these animals. Low levels of M / E ratio may be associated with a regenerative anemia in extravascular hemolysis function or even the ineffective erythropoiesis. From the myelogram there was also a significant reduction of blast cells and all cell types, especially of granulocytic lineage, with a predominance of lymphoid lineage. However, since lymphocytes are, continuously by recirculating the increase or decrease in these cells do not necessarily reflect changes in lymphopoiesis. The pathological examination of the bone marrow of the experimental group animals showed a progressive increase in cellularity, featuring medullary hyperplasia. These results correlate to myelogram. In the regenerative anemia occurs a decreased survival of red blood cells in the circulation, resulting from extravascular hemolysis performed by macrophages, especially in the splenic tissue. Thus, the long term administration of S. occidentalis seeds could be associated with hemolytic process, due to the observation of an increase in the relative weight of this body; hemosiderin accumulation in the spleen and also increased reticulocytes in animals treated with this plant. The treatment with S. occidentalis promoted also significant reduction in cellularity of the spleen and pathological changes, including capsule and cell thinning thickening. Clonogenic assays showed decreased percentage of BFU-E and CFU-E colonies in animals from So2% group, indicating a probable toxic action of S.occidentalis on medullary progenitors. Therefore, the treatment for 90 days with S. occidentalis in feed is promotes blood toxicity.

Aspectos histológicos de fragmentos esplênicos autotransplantados em ratos / Histopathologic aspects of splenic fragments autotransplanted in rats

Estudou-se a viabilidade do autotransplante de tecido esplênico, um terço do baço, associado à esplenectomia parcial, e verificou-se a cinética evolutiva de sua regeneração, sob o aspecto macroscópico e histológico. Foram utilizados 28 ratos Wistar, adultos, machos, com média de peso de 300g, distribuídos em quatro grupos experimentais. Cada animal foi submetido à esplenectomia parcial, e um fragmento de baço foi transplantado para o omento maior, por períodos de 30, 60, 90 e 120 dias. Após cada período pré-estipulado, os tecidos esplênicos autotransplantados foram coletados e analisados histologicamente. Os resultados mostraram regeneração da cápsula esplênica, dos vasos sanguíneos e das polpas branca e vermelha. Aos 90 dias, a arquitetura microscópica apresentava-se semelhante à do baço normal.(AU)

The splenic tissue autograft viability (one third of the spleen) associated to parcial splenectomy was studied to verify the evolutive kinetic of its regeneration by macroscopic and histological aspects. Twenty-eight adult male Wistar rats, weighting 300g, were distributed in four experimental groups. Each animal was submitted to parcial splenectomy and one fragment of each spleen was autotransplanted to the greater omentum, for a period of 30, 60, 90, and 120 days. After each period, the autotransplanted splenic tissues were collected and histopathologically analyzed. The results showed regeneration of the splenic capsule, blood vessels, white pulp, and red pulp. After 90 days, the microscopic architecture was similar to the normal spleen.(AU)

Utilização da cápsula esplênica de bovino na ceratoplastia lamelar em coelhos / The use of bovine esplenic capsule in lamellar keratoplasty with rabbits / Utilización de cápsula esplénica de bovino en la queratoplastía lamelar en conejos

Para reparo de ceratectomias superficiais de 15 coelhos, foi utilizada cápsula esplênica de bovino conservada em glicerina a 98%. Os animais foram separados em cinco grupos de igual número e submetidos às observações clínicas e histopatológicas ao final do 3, 7, 15 ,30 e 60 dias de pós-operatório (PO). Os animais apresentaram boa evolução clínica, com presença de blefaroespasmo e neovascularização de intensidade moderada nas fases iniciais, com regressão e desaparecimento nos períodos intermediários e tardios de observações. O material implantado ocasionou edema de córnea, infiltração de polimorfonucleares, neoformação vascular e mínima reação inflamatória. O que permitiu regeneração do tecido corneal aos 30 dias de PO. A cápsula esplênica de bovinos conservada em glicerina a 98% foi eficiente na reparação de feridas lamelares em córnea de coelhos.(AU)

A 98%-glycerin-preserved bovine capsule was used to fix superficial ceractomonies in rabbits. . The animals were separated into five groups of equal number, and submitted to both clinical and histological observation at the end of the 3rd, 7th, 15th, 30th, and 60th (PO) postoperative days. The animals presented good clinical evolution, moderate blefaroespasm and neovascularization in the former stages, regression and disappearing in the intermediate and latter observation ones. The implanted material caused corneal edema, nuclear polymorphous infiltration, neovascularization and minimum inflammatory reaction, which allowed the regeneration of the corneal tissue in 30 days. The 98%-glycerin-preserved bovine capsule was efficient in the repairing of the lamellar wounds in rabbits´cornea.(AU)

Para el reparo de ceratectomías superficiales de 15 conejos, fue utilizada cápsula esplénica de bovino conservada en glicerina a 98%. Los animales fueron separados en cinco grupos de igual número y sometidos a las observaciones clínicas e histopatológicas al final del 3, 7, 15, 30 y 60 días de posoperatorio (PO). Los animales presentaron buena evolución clínica, con presencia de blefaroespasmo y neovascularización de intensidad moderada en las fases iniciales, con regresión y desaparición en los períodos intermediarios y tardíos de observaciones. El material implantado ocasionó edema de córnea, infiltración de polimorfonucleares, neoformación vascular y mínima reacción inflamatoria. Lo que permitió regeneración de tejido corneal a los 30 días de PO. La cápsula esplénica de bovinos conservada en glicerina a 98% fue eficiente en la reparación de heridas lamelar en córnea de conejos.(AU)

Estudo histológico da regeneração esplênica de ratos submetidos a esplenectomia subtotal

An increase susceptibility to overwhelming infection is now a well-recognized complication of splenectomy. A number of alternatives to splenectomy have been proposed that could possibly prevent this complication of the asplenic state. The present study analize the histological regeneration of the splenic tissue in rats underwent to subtotal splenectomy. Thirty adult male Wistar rats were used, weighing 160 to 210g. The rats were underwent to subtotal splenectomy, divided into three groups of ten rats each, and analized after 15, 30, and 45 days. After this period of time the splenic tissue were withdrawn and submitted to histological examination. The splenic tissue structure on the 15th day was irregular without necrosis. The histological examination on the 30th day, the splenic tissue in the capsule was now with a greater development. After 45th day, an important similarity was observed between the splenic tissue recovered and the normal spleen in all its details. The present study showed that the spleen underwent to subtotal splenectomy regenerat completely in a period of 45 days.

Um aumento da susceptibilidade à infecção severa é uma complicação reconhecida da esplenectomia. Um grande número de alternativas tem sido propostas que poderiam impedir esta complicação do estado asplênico. O presente estudo analisa a regeneração histológica do tecido esplênico em ratos submetidos a esplenectomia subtotal. Foram utilizados trinta ratos machos da linhagem Wistar, adultos, pesando entre 160 e 210g. Os animais foram submetidos a esplenectomia subtotal e divididos em três grupos contendo dez ratos cada onde foram estudados após 15, 30 e 45 dias. Após este período de observação o tecido esplênico foi recuperado e submetido a exame histológico. A estrutura tecidual esplênica no 15º dia se apresentava irregular, porém sem necrose. Após 30 dias , a cápsula se apresentava histologicamente espessada e com maior desenvolvimento. Em 45 dias foi observado semelhança considerável entre o tecido esplênico remanescente e o baço normal. O presente estudo mostra que o baço submetido a esplenectomia subtotal se regenera completamente em um período de 45 dias.