RESUMEN
During the ovarian ontogeny in birds, five fundamental events can be recognized: migration and colonization of the primordial germ cells, differentiation and proliferation of oogonies, an organization of germinal nests, beginning of the meiotic process and folliculogenesis. The knowledge of these events is fundamental for the interpretation of the processes involved in the differentiation of female gametes. However, there are only references for some model species such as Gallus gallus domesticus and Coturnix coturnix. In a previous study, the histological structure of embryonic ovaries of Columba livia was revealed. Therefore, the objective of this work is to characterize the processes of meiosis and folliculogenesis C. livia from the analysis of the expression of the GnRH receptor, the 3ßHSD enzyme and the cell proliferation protein PCNA in embryonic and postnatal ovaries. Therefore, the expression of GnRHR, 3ßHSD, and PCNA was revealed in histological testicular and ovarian preparations in embryos (stages 41-43) and neonates (2, 5, 7, 10 and 75â¯days post-hatching). The present study demonstrates that the fate of germline cells is dictated by their location during gonadal development. Thus, the germline cells located in the cortex of the left gonad enter meiosis, while those in the right gonad and those in the medulla of the left ovary fail to go into meiosis. This indicates that somatic signals, instead of an autonomous cellular mechanism, regulate the entry of the germline cells into meiosis in the C. livia embryo. Future studies will be focused on the analysis of proteins associated with meiotic events and folliculogenesis in embryonic and neonatal ovaries of C. livia, to evaluate the regulation of meiosis in vitro.
Asunto(s)
3-Hidroxiesteroide Deshidrogenasas/metabolismo , Columbidae/metabolismo , Meiosis , Folículo Ovárico/crecimiento & desarrollo , Receptores LHRH/metabolismo , Animales , Proliferación Celular , Columbidae/embriología , Embrión no Mamífero/citología , Femenino , Células Germinativas/metabolismo , Inmunohistoquímica , Oocitos/citología , Oocitos/metabolismo , Folículo Ovárico/metabolismo , Antígeno Nuclear de Célula en Proliferación/metabolismoRESUMEN
The spatial organization of cells during tissue differentiation is a crucial process in the morphogenesis of vertebrates. This process involves the movement, separation, and connection of cells. It is essential to elucidate the molecular mechanisms involved in these processes for the understanding of animal morphogenesis. Cell-cell adhesion molecules, called cadherins, are involved in the selective adhesion of cells. In the case of birds, the expression of these molecules in various organ systems during embryonic development has been reported in Gallus gallus domesticus. In this work, we present the immunohistochemical analysis of the differential expression of E and N-cadherin binding molecules in Columba livia embryos at various stages of gonadal morphogenesis. The expression of E and N-cadherin in embryos corresponding to the stages 41, 43 and in neonates of 2, 5, 7 and 75 post-hatching days were assessed by immunohistochemistry. Results revealed the expression of N-cadherin in the plasma membrane and the perinuclear zone of germline cells in ovaries and testes. However, the expression of E-cadherin was noticed with similar immunoreactivity pattern, in Sertoli cells and in the cells of the follicular nests. The differential expression of follicular cells and Sertoli cells positive for E-cadherin and germline cell N-cadherin positive cells were evidenced in the present work at the cell-cell interaction level. Future studies will focus on determining the expression of E and N-cadherin molecules during the migration of the primordial germ cells and the colonization of the genital ridge.
Asunto(s)
Cadherinas/metabolismo , Pollos/metabolismo , Morfogénesis/fisiología , Testículo/metabolismo , Animales , Columbiformes , Femenino , Inmunohistoquímica/métodos , Masculino , Ovario/metabolismo , Células de Sertoli/citologíaRESUMEN
In this work, testicular ontogeny is analyzed at the anatomical, histological and immunohistochemical levels; the latter through the detection of GnRHR and PCNA in the testicles of embryos, neonates and juveniles of Columba livia. We analyzed 150 embryos, 25 neonates and 5 juveniles by means of observations under a stereoscopic magnifying glass and scanning electron microscope (SEM). The histological analysis was performed using hematoxylin-eosin staining techniques and the PAS reaction. For the immunohistochemical analysis, the expression of GnRHR and PCNA in embryos corresponding to stages 41, 43 and in neonates of 2, 5, 7 and 75 days post-hatch was revealed in testicular histological preparations. That gonadal outline is evident in stage 18. In stage 29, the testes are constituted of a medulla in which the PGCs are surrounded by the Sertoli cells, constituting the seminiferous tubules. From stage 37 a greater organization of the tubules is visualized and at the time of hatching the testicle is constituted of the closed seminiferous tubules, formed of the PGCs and Sertoli cells. The Leydig cells are evident outside the tubules. In the juvenile stages, the differentiation of germline cells and the organization of small vessels that irrigate the developing testicle begin to be visible. In the analyzed stages, the immunodetection of the GnRHR receptor and PCNA revealed specific marking in the plasma membrane and in the perinuclear zone for GnRHR and in the nucleus of the germline cells in juvenile testicles for PCNA. These results can be used as a basis for further study of endocrine regulation events during testicular ontogeny in avian species.