SPINDLE MEMBRANES DURING SPERMATOGENESIS IN DERMATOBIA-HOMINIS (DIPTERA, CUTEREBRIDAE)

During the mitotic and meiotic division in Dermatobia hominis spermatogenesis, the nuclear envelope is fragmented and membranes appear around the spindle. The membranes surrounding the mitotic spindle are formed by two layers of cisterns. The membranes of the meiotic spindle consist in at least 3 or 4 layers of long smooth cisterns which isolate the spindle from the remaining cytoplasm. The presence of this kind of membranes during meiosis seems to be usual in insect male germ cell.

Activity of the Ovarian Germinal Epithelium in the Freshwater Catfish, Pimelodus maculatus (Teleostei: Ostariophysi: Siluriformes): Germline Cysts, Follicle Formation and Oocyte Development

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tumor estromal gastrointestinal (TEGI): estudo morfológico e imunohistoquímico de dez casos.

To study the histogenesis of spindle and epithelioid cell tumors of gastrointestinal tract we evaluated ten cases of gastrointestinal stromal tumors (GIST) previously classified as leiomyomas (6 cases) and leiomyosarcomas (4 cases). The cases were studied by morphological and immunohistochemistry procedures with search of three markers: muscle specific actin (HHF-35), vimentin and S-100 protein. All tumors showed vimentin positivity. Muscle differentiation was demonstrated in three cases (33.3%), all of them benign. One tumor, in small intestine, displayed S-100 protein positivity. The results showed that the GIST represent a heterogeneous group of tumors, most of which consist of primitive mesenchymal cells.

The ultrastructure of the pre-meiotic and meiotic stages of spermatogenesis in Plagioscion squamosissimus (Teleostei, Perciformes, Sciaenidae)

Spermatogenesis of 'corvina' P. squamosissimus starts from a stem cell that gives rise to germ cells. These cells are enveloped by Sertoli cells, forming cysts. The germ cells in the cysts are all at the same stage of development and are interconnected by cytoplasmic bridges. Spermatogonia are the largest germ cells. In the cysts, these cells differentiate into primary spermatogonia and secondary spermatogonia. The primary spermatogonia are isolated in the cyst and give rise to the secondary spermatogonia. After several mitotic divisions, they produce spermatocytes I, which can be identified by synaptonemal complexes in the nucleus. The spermatocytes I enter the first phase of meiosis to produce the spermatocytes II. These are not very frequently seen because they rapidly undergo a second phase of meiosis to produce spermatids.

Desenvolvimento morfolôgico dos ovários em embriões e fetos bovinos da raça Nelore

The morphologic events related to the prenatal development of the ovaries in 81 Nelore breed embryos and fetuses gathered in a local slaughterhouse, with age range from 26 to 240 days following fecundation were studied. The age of fetuses was estimated from measures taken in the cranium-caudal direction. The sex was identified from macroscopic observations and using Polymerase Chain Reaction (PCR) technique. For histology the gonads were fixed in Bourn's fluid for 24 hours and 5 μm thick section's were stained with hematoxylin-eosin. Formation of gonadal ridge and presence of germinal cells were found within it at 29 and 34 days, respectively. Oogonia and primordial follicles, unlike the growing follicles, exhibited significant differences in diameter in the various periods studied. Positive correlation (P<0.05) was found between the diameter of oogonia and their nucleus as well as between primordial and growing follicles with their oocytes and respective nuclei. The gonad was fully formed at 40 days. Primordial follicles, in the growing stage, and antral follicles first appeared, approximately at 95, 140, and 180 days, respectively. Despite the onset and duration of oogenesis being similar to that of taurine breeds, folliculogenesis initiates at an early stages in the Nelore breed.

Organização celular dos testículos em Hylidae e leptodactylidae, no Pantanal (Estado do Mato Grosso do Sul, Brasil)

The objective of this work was to make a comparative analysis of germ cell organization at different stages of cellular differentiation in adult males of Dendropsophus nanus (Boulenger, 1889), Pseudis limellum (Cope, 1862), P. paradoxa (Linnaeus, 1758), and Scinax acuminatus (Cope, 1862), belonging to the family Hylidae; and Leptodactylus chaquensis (Cei, 1950) and L. podicipinus (Cope, 1862), belonging to the family Leptodactylidae, collected in the Pantanal and in Serra da Bodoquena, Mato Grosso do Sul State, Brazil. The testes were removed and fixed, dehydrated in a graded series of ethanol and embedded in methacrylate glycol resin (Historesin Leica®). The sections were stained by 1% toluidine blue and observed under light microscope. It was detected that all individual of the Hylidae family show, throughout the year, the presence of all germ cell types of spermatogenesis. However, all Leptodactylidae family individuals only show the presence of all germ cell types during the rainy season. The variations of characteristics in seminiferous epithelium organization, as well as the evident difference in the amount of spermatozoa inside the tubules, are evidence that the anurans in this work show different forms of spermatogenesis development throughout the year: the cycle is continuous for the Hylidae family, and discontinuous with explosive release of spermatozoa for the Leptodactylidae family.

Expression of acid phosphatase in the seminiferous epithelium of vertebrates

Acid phosphatases (AcPs) are known to provide phosphate to tissues that have high energy requirements, especially during development, growth and maturation. During spermatogenesis AcP activity is manifested in heterophagous lysosomes of Sertoli cells. This phagocytic function appears to be hormone-independent. We examined the expression pattern of AcP during the reproductive period of four species belonging to different vertebrate groups: Tilapia rendalli (Teleostei, Cichlidae), Dendropsophus minutus (Amphibia, Anura), Meriones unguiculatus (Mammalia, Rodentia), and Oryctolagus cuniculus (Mammalia, Lagomorpha). To demonstrate AcP activity, cryosections were processed for enzyme histochemistry by a modification of the method of Gömöri. AcP activity was similar in the testes of these four species. Testes of T. rendalli, D. minutus and M. unguiculatus showed an intense reaction in the Sertoli cell region. AcP activity was detected in the testes of D. minutus and O. cuniculus in seminiferous epithelium regions, where cells are found in more advanced stages of development. The seminiferous epithelium of all four species exhibited AcP activity, mainly in the cytoplasm of either Sertoli cells or germ cells. These findings reinforce the importance of AcP activity during the spermatogenesis process in vertebrates. © FUNPEC-RP.

Gametogenesis and reproductive cycle of Melanorivulus aff. punctatus (Boulenger, 1895) (Cyprinodontiformes, Rivulidae) in Chapada dos Guimarães, Mato Grosso, Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Immunoexpression of aromatase and estrogen receptors β in stem spermatogonia of bullfrogs indicates a role of estrogen in the seasonal spermatogonial mitotic activity

Bullfrog stem spermatogonia, also named primordial germ cells (PGCs), show strong testosterone immunolabeling in winter, but no or weak testosterone immunoexpression in summer. Thus, the role of testosterone in these cells needs to be clarified. In this study, we proposed to evaluate whether PGCs express aromatase and estrogen receptors, and verify a possible role of estrogen in PGCs seasonal proliferation. Testes of male adult bullfrogs, collected in winter (WG) and summer (SG), were fixed and embedded in historesin, for quantitative analysis, or paraffin for immunohistochemistry (IHC). The number of haematoxylin/eosin stained PGCs/lobular area was obtained. Proliferating cell nuclear antigen (PCNA), aromatase, estrogen receptor β (ERβ) and PCNA/ERβ double immunolabeling were detected by IHC. The number of PCNA-positive PGCs and the histological score (HSCORE) of aromatase and ERβ immunolabeled PGCs were obtained. Although the number of PGCs increased significantly in WG, a high number of PCNA-positive PGCs was observed in summer. Moreover, aromatase and ERβ HSCORE was higher in SG than WG. The results indicate that PGCs express a seasonal proliferative activity; the low mitotic activity in winter is related to the maximal limit of germ cells which can be supported in the large lobules. In SG, the increased ERβ and aromatase HSCORE suggests that testosterone is converted into estrogen from winter to summer. Moreover, the parallelism between the high PGCs mitotic activity and ERβ immunoexpression suggest a participation of estrogen in the control of the PGCs seasonal proliferative activity which guarantee the formation of new germ cysts from summer to next autumn. © 2012 Elsevier Inc.

Avaliação do espermograma de cães submetidos à administração de cisplatina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da expressão da cicloxigenase-2 de macrófagos em diferentes graus histológicos de mastocitoma canino

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alterações no número de cópias genômicas em mastocitomas cutâneos caninos

Pós-graduação em Medicina Veterinária - FCAV

Estudo retrospectivo dos aspectos cirúrgicos do protocolo cooperativo brasileiro para o tratamento dos tumores de células germinativas na infância: repercussão no prognóstico em função da adesão do cirúrgião ao protocolo cirúrgico

Pós-graduação em Bases Gerais da Cirurgia - FMB

Mastocitoma canino: abordagem histopatológica e imunoistoquímica na busca de biomarcadores prognósticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização do ciclo nucleolar e da formação do corpo cromatóide na espermatogênese de alguns vertebrados

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)