Cell repertoire and proliferation of germinative cells of the model cestode Mesocestoides corti.

The phylum Platyhelminthes shares a unique population of undifferentiated cells responsible for the proliferation capacity needed for cell renewal, growth, tissue repair and regeneration. These cells have been extensively studied in free-living flatworms, whereas in cestodes the presence of a set of undifferentiated cells, known as germinative cells, has been demonstrated in classical morphology studies, but poorly characterized with molecular biology approaches. Furthermore, several genes have been identified as neoblast markers in free-living flatworms that deserve study in cestode models. Here, different cell types of the model cestode Mesocestoides corti were characterized, identifying differentiated and germinative cells. Muscle cells, tegumental cells, calcareous corpuscle precursor cells and excretory system cells were identified, all of which are non-proliferative, differentiated cell types. Besides those, germinative cells were identified as a population of small cells with proliferative capacity in vivo. Primary cell culture experiments in Dulbecco's Modified Eagle Medium (DMEM), Echinococcus hydatid fluid and hepatocyte conditioned media in non-reductive or reductive conditions confirmed that the germinative cells were the only ones with proliferative capacity. Since several genes have been identified as markers of undifferentiated neoblast cells in free-living flatworms, the expression of pumilio and pL10 genes was analysed by qPCR and in situ hybridization, showing that the expression of these genes was stronger in germinative cells but not restricted to this cell type. This study provides the first tools to analyse and further characterise undifferentiated cells in a model cestode.

Key characteristics of the ovary and uterus for reproduction with particular reference to poly ovulation in the plains viscacha (Lagostomus maximus, chinchillidae).

One of the dogmas of mammalian reproduction states is that primordial germ cells in females are restricted to the intrauterine phase, and that only a small portion of oocytes is available for ovulation during the adult life. Among the rare exceptions to this rule is the plains viscacha. This specie polyovulates up to 800 oocytes per cycle, from which 10 to 12 are implanted, but only 1-2 conceptuses survive. To better understand the key mechanisms of this pattern of embryonic to uterine interactions, we analyzed 19 female genital systems by means of gross morphology, histology, stereology and immunohistochemistry. Data showed that a specialized, highly convoluted structure of the ovarian cortex developed during the intrauterine phase as a prerequisite for the massive super-ovulation, likely associated with the inhibition of apoptosis and continued proliferation of germ cells, as well as maintenance of several corpora lutea during the adult life. In addition, specializations of uterine vasculature and musculature were demonstrated. Altogether, these key morphological characteristics evolved in order to contribute as compensatory or controlling mechanism for polyovulation and polyimplantation that led these species into becoming an unique enigma in reproductive biology, and a potential animal model to provide explanations regarding to developmental specializations.

Ovarian dysgerminoma causing multifocal metastases in young bitch / Disgerminoma ovariano causando metástases multifocais em cadela jovem

The ovarian neoplasias are unusual in canine species, mainly originated from germinative cells. Among these, dysgerminoma is a rare neoplasm in bitches, predominantly affecting senile and small and medium breeds. They are large, rounded, smooth surface, painless and firm in consistency. The clinical signs commonly demonstrated by patients with this neoplasia are abdominal distension and secondary signs of hyperestrogenism. The diagnosis should be based on the association of history, clinical signs, radiographic, ultrasonographic, cytological, histopathological and immunohistochemical exams. The treatment is the surgical castration and metastases are uncommon. Due to the rarity in bitches, specifically the young animals, this study aimed to describe a case of left ovarian dysgerminoma, of considerable size and adherence in adjacent organs, in a Brazilian Fila, whose showed considerable increase in abdominal volume and progressive weight loss. The diagnosis was confirmed by means of complementary x-ray, ultrasound, histopathological and immunohistochemical tests. Even with the recommended surgical treatment (castration), the patient demonstrated severe respiratory symptoms and increased abdominal volume after two months, and the complementary exams suggested pulmonary and multifocal metastases and the tutor chose euthanasia. As presented by the results, although rare in bitches, dysgerminoma should be included in the differential of ovarian neoplasias, including the young ones.

As neoplasias ovarianas são de ocorrência incomum na espécie canina, principalmente as originadas de células germinativas. Dentre estas, o disgerminoma é uma neoplasia rara em cadelas, acometendo predominantemente fêmeas senis e de raças pequenas e médias. Apresentam-se como massas grandes, arredondadas, de superfície lisa, indolores e de consistência firme. Os sinais clínicos comumente demonstrados por pacientes com este tipo neoplásico incluem distensão abdominal e sinais secundários de hiperestrogenismo. O diagnóstico deve ser baseado na associação do histórico, sinais clínicos, exames radiográficos, ultrassonográficos, citológicos, histopatológicos e imunohistoquímicos. O tratamento de escolha é a castração cirúrgica, sendo que as metástases são incomuns. Perante a raridade em cadelas, em específico as jovens, este relato teve como propósito discorrer um caso de disgerminoma ovariano esquerdo, de tamanho considerável e aderência em órgãos adjacentes, em uma Fila Brasileira, cuja sintomatologia incluiu considerável aumento de volume abdominal e emagrecimento progressivo. O diagnóstico foi confirmado por meio de exames complementares de raios-x, ultrassom, histopatológico e imunohistoquímicos. Mesmo com a instituição dotratamento cirúrgico preconizado (castração), a paciente demonstrou grave sintomatologia respiratória e aumento de volume abdominal após dois meses e, como os exames complementares foram sugestivos de metástases pulmonares e multifocais, o tutor optou pela eutanásia. Diante dos resultados, pode-se admitir que apesar de raro em cadelas, o disgerminoma deve ser incluído no diferencial das neoplasias ovarianas, incluindo as jovens.

The quantification of testicular cells during the postnatal development in two Caviomorph rodents: the guinea pig (Cavia porcellus) and the cutia (Dasyprocta agouti)

ABSTRACT The germinative, Sertoli and Leydig cells of two caviomorph rodents (Cavia porcellus and Dasyprocta agouti) were counted as well as the estimation of the total volume of the testis and the total volume of seminiferous tubules and interstitium in prepubertal, pubertal and adult animals. The number of spermatogonia, spermatocytes and spermatids cells increased during the pubertal phase in both rodents, notably the spermatid cells. The spermatocyte and spermatid slightly decreased in the adult of both rodents, but the increment in spermatogonia cells number was seen, mainly in cutias. The number of Sertoli cells increased in pubertal rodents, but in the adult the number reduced. Substantial number of Leydig cells was counted in pubertal and adult guinea pigs. In cutias, the number of Leydig cells increased in pubertal phase and decline in adults. The design-based stereological method has proven to be unbiased and reliable to be applied in reproduction studies.

Recent advances in Echinococcus genomics and stem cell research.

Alveolar and cystic echinococcosis, caused by the metacestode larval stages of the tapeworms Echinococcus multilocularis and Echinococcus granulosus, respectively, are life-threatening diseases and very difficult to treat. The introduction of benzimidazole-based chemotherapy, which targets parasite ß-tubulin, has significantly improved the life-span and prognosis of echinococcosis patients. However, benzimidazoles show only parasitostatic activity, are associated with serious adverse side effects and have to be administered for very long time periods, underlining the need for new drugs. Very recently, the nuclear genomes of E. multilocularis and E. granulosus have been characterised, revealing a plethora of data for gaining a deeper understanding of host-parasite interaction, parasite development and parasite evolution. Combined with extensive transcriptome analyses of Echinococcus life cycle stages these investigations also yielded novel clues for targeted drug design. Recent years also witnessed significant advancements in the molecular and cellular characterisation of the Echinococcus 'germinative cell' population, which forms a unique stem cell system that differs from stem cells of other organisms in the expression of several genes associated with the maintenance of pluripotency. As the only parasite cell type capable of undergoing mitosis, the germinative cells are central to all developmental transitions of Echinococcus within the host and to parasite expansion via asexual proliferation. In the present article, we will briefly introduce and discuss recent advances in Echinococcus genomics and stem cell research in the context of drug design and development. Interestingly, it turns out that benzimidazoles seem to have very limited effects on Echinococcus germinative cells, which could explain the high recurrence rates observed after chemotherapeutic treatment of echinococcosis patients. This clearly indicates that future efforts into the development of parasitocidal drugs should also target the parasite's stem cell system.

Histology of the gonads of the hybrid Pseudoplatystoma punctifer X Leiarius marmoratus / Histologia das gônadas do híbrido Pseudoplatystoma punctifer X Leiarius marmoratus

Considering the rapid expansion of fish farming in intensive systems and the use of hybrids in Brazil, the study regarding the breeding capacity of the most recent hybrid is of ecological importance. If these animals are fertile, they may breed with the parental species in the wild and can negatively affect the genetic variability of the population (parental species in the wild). Fragments of the gonads were collected and submitted to histological evaluation. Histological cuts were stained with eosin/hematoxilin and toluidine, and slides were randomly selected for observation of three fields each animal, through light microscopy. Gonads of all fishes were paired structures of elongated shape in the abdominal cavity, covered by an albuginea tunic. Male juveniles presented primary spermatocytes while juvenile females presented chromatine nucleolus oocytes. Adult females presented chromatin-nucleolus oocytes, perinuclear, cortical alveoli, and vitellogenic oocytes visible in various sizes. The presence of oocytes in different stages and primary spermatocytes indicate that these fish may be fertile. Fish hybridization represents a threat to the conservation of native species.

Considerando a rápida expansão da piscicultura em sistemas intensivos e do uso de híbridos no Brasil, o estudo sobre a capacidade de reprodução do híbrido é de importância ecológica. Caso estes animais sejam férteis, podem afetar negativamente a variabilidade genética da população (espécies parentais em estado selvagem). Fragmentos das gônadas foram coletados e submetidos à avaliação histológica. Os cortes histológicos foram corados com eosina/hematoxilina e toluidina, e selecionados aleatoriamente para observação de três campos de cada animal, através de microscopia de luz. Gônadas de todos os peixes apresentaram-se como estruturas emparelhadas de forma alongada na cavidade abdominal, cobertas por uma túnica albugínea. Juvenis do sexo masculino apresentaram espermatócitos primários, enquanto as fêmeas juvenis apresentaram ovócitos cromatina nucléolo nos ovários. Fêmeas adultas apresentaram ovócitos cromatinanucléolo nos ovários, alvéolo cortical, perinuclear e vitelogênico, visíveis em vários tamanhos. A presença de ovócitos em diferentes fases e espermatócitos primários indicam que estes peixes podem ser férteis. A hibridação de peixes pode representar uma ameaça à conservação das espécies nativas.

Histology of the gonads of the hybrid Pseudoplatystoma punctifer X Leiarius marmoratus / Histologia das gônadas do híbrido Pseudoplatystoma punctifer X Leiarius marmoratus

Considering the rapid expansion of fish farming in intensive systems and the use of hybrids in Brazil, the study regarding the breeding capacity of the most recent hybrid is of ecological importance. If these animals are fertile, they may breed with the parental species in the wild and can negatively affect the genetic variability of the population (parental species in the wild). Fragments of the gonads were collected and submitted to histological evaluation. Histological cuts were stained with eosin/hematoxilin and toluidine, and slides were randomly selected for observation of three fields each animal, through light microscopy. Gonads of all fishes were paired structures of elongated shape in the abdominal cavity, covered by an albuginea tunic. Male juveniles presented primary spermatocytes while juvenile females presented chromatine nucleolus oocytes. Adult females presented chromatin-nucleolus oocytes, perinuclear, cortical alveoli, and vitellogenic oocytes visible in various sizes. The presence of oocytes in different stages and primary spermatocytes indicate that these fish may be fertile. Fish hybridization represents a threat to the conservation of native species.(AU)

Considerando a rápida expansão da piscicultura em sistemas intensivos e do uso de híbridos no Brasil, o estudo sobre a capacidade de reprodução do híbrido é de importância ecológica. Caso estes animais sejam férteis, podem afetar negativamente a variabilidade genética da população (espécies parentais em estado selvagem). Fragmentos das gônadas foram coletados e submetidos à avaliação histológica. Os cortes histológicos foram corados com eosina/hematoxilina e toluidina, e selecionados aleatoriamente para observação de três campos de cada animal, através de microscopia de luz. Gônadas de todos os peixes apresentaram-se como estruturas emparelhadas de forma alongada na cavidade abdominal, cobertas por uma túnica albugínea. Juvenis do sexo masculino apresentaram espermatócitos primários, enquanto as fêmeas juvenis apresentaram ovócitos cromatina nucléolo nos ovários. Fêmeas adultas apresentaram ovócitos cromatinanucléolo nos ovários, alvéolo cortical, perinuclear e vitelogênico, visíveis em vários tamanhos. A presença de ovócitos em diferentes fases e espermatócitos primários indicam que estes peixes podem ser férteis. A hibridação de peixes pode representar uma ameaça à conservação das espécies nativas.(AU)

Maintenance of the corneal epithelium is carried out by germinative cells of its basal stratum and not by presumed stem cells of the limbus

The purpose of this investigation was to analyze the proliferative behavior of rabbit corneal epithelium and establish if any particular region was preferentially involved in epithelial maintenance. [3H]-thymidine was injected intravitreally into both normal eyes and eyes with partially scraped corneal epithelium. Semithin sections of the anterior segment were evaluated by quantitative autoradiography. Segments with active replication (on) and those with no cell division (off) were intermingled in all regions of the tissue, suggesting that the renewal of the epithelial surface of the cornea followed an on/off alternating pattern. In the limbus, heavy labeling of the outermost layers was observed, coupled with a few or no labeled nuclei in the basal stratum. This suggests that this region is a site of rapid cell differentiation and does not contain many slow-cycling cells. The conspicuous and protracted labeling of the basal layer of the corneal epithelium suggests that its cells undergo repeated cycles of replication before being sent to the suprabasal strata. This replication model is prone to generate label-retaining cells. Thus, if these are adult stem cells, one must conclude that they reside in the corneal basal layer and not the limbal basal layer. One may also infer that the basal cells of the cornea and not of the limbus are the ones with the main burden of renewing the corneal epithelium. No particular role in this process could be assigned to the cells of the basal layer of the limbal epithelium.