J. Morphol. Sci., 2013, vol. 30, no. 1, p. 21-27 21 Original article Morphologic features from mdx mice spleens, used for duchenne muscular dystrophy studies Santos, AC. 1 *, Oliveira, DM. 1 , Bertassoli, BM. 1 , Viana, DC. 2 , Vasconcelos, BG. 2 and Assis Neto, AC. 3 1 Masters degree, Department of Wild and Domestic Animals, Faculty of Veterinary Medicine and Animal Science – FMVZ, São Paulo University – USP, Av. Professor Doutor Orlando Marques de Paiva, 87, CEP 05508-270, São Paulo, SP, Brazil 2 PhD student, Department of Wild and Domestic Animals, Faculty of Veterinary Medicine and Animal Science – FMVZ, São Paulo University – USP, Av. Professor Doutor Orlando Marques de Paiva, 87, CEP 05508-270, São Paulo, SP, Brazil 3 PhD Professor, Descriptive Anatomy of Domestic Animals, Department of Wild and Domestic Animals, Faculty of Veterinary Medicine and Animal Science – FMVZ, São Paulo University – USP, Av. Professor Doutor Orlando Marques de Paiva, 87, CEP 05508-270, São Paulo, SP, Brazil *E-mail: amiltonsantoss@usp.br Abstract The mdx mice model is widely used for Duchenne muscular dystrophy (DMD) studies, which is present in a high percentage from newborns human males. Therefore, the aim of this study was to evaluate possible morphological changes from spleens in these mice and to compare with normal mice (Mus musculus) in contribution to DMD understanding and its consequences on immune system by affected individuals. The study was performed by light and scanning electron microscopy (SEM) techniques beyond immunohistochemistry. Was found microscopically an increased number of lymph nodes and decreased in red pulp region by mdx, beyond a larger VEGF-C (vascular endothelial growth factor C) expression stimulates lymphangiogenesis in red pulp region from spleen. These indings suggest a spleen adaptation in order to supply immunological demand due upper respiratory infection, which are common in individuals affected by Duchenne muscular dystrophy. Keywords: lymph nodes, lymphocytes, muscular dystrophy, red pulp, respiratory inlammation. 1 Introduction The Duchenne Muscular Dystrophy (DMD) is a neuromuscular hereditary disease, which is character-linked recessive X chromosome. This disease is found only in boys at rate one to each 3500 newborns. Muscular dystrophies linked to X chromosome are described in other species such as mice (mdx), dogs (GRMD) and cats (HFMD). Thus, because these animals are homologous to DMD, it has been widely used as a model for the disease (FADIC, 2005). The absence of dystrophin protein gene in dystrophic diseases provides increased permeability in muscle membranes, increasing calcium concentration, leading enzymes activation that cause breakdown in muscle cells (BERGMAN, INZANA, MONROE et al., 2002). The loss of ability to regeneration could be a result from myogenic cells exhaustion caused by an excessive degeneration and regeneration cycles (LUZ, MARQUES and SANTO-NETO, 2002). In this regard, the mdx mice are a widely used model for human DMD studies due easier reproduction, genetic uniformity, economy and convenience for laboratory experiments (SEIXAS, LAGROTA-CANDIDO, WILSON et al., 1997; LYNCH, HINKLE and FAULKNER, 2001; GOSSELIN, BARKLEY, SPENCER et al., 2003). Therefore, the aim here was to verify possible morphophysiological changes due muscular dystrophy from mdx mice spleen and thus contribute to the clinical, surgical and pathological anatomy, since there are few studies related to the changes of the immune system by Duchenne muscular dystrophy affected individuals. 2 Material and methods 2.1 Animals Were utilized ive mdx mice males and ive normal mice (Mus musculus) aged ive months from Science Biomedical Institute (ICB) by São Paulo University, São Paulo, Brazil. This research was approved by the bioethics committee of the Faculty of Veterinary Medicine and Animal Science at São Paulo University (FMVZ/USP). 2.2 Euthanasia and collects The animals were euthanized by anesthetic ketamine 50 mg/kg (Ketamin-S ® , Cristália) associated with 2 mg/kg xilazina hydrochloride (Calmiun ® , Union Agener) by intraperitoneal way. The spleens were macroscopically analyzed, measured, collected and ixed on paraformaldehyde 4%. 2.3 Laboratories To the performance this work we used Histology, Embryology and Electron Microscopy Laboratories of Faculty of Veterinary Medicine and Animal Science at São Paulo University, São Paulo-SP.