Ana Carolina Furlanetto Mançanares

Immunolocalization of proteins in the spermatogenesis process of canine

Spermatogenesis is a process in which differentiated cells are produced and the adult stem cell population-known as spermatogonial stem cells (SSCs)-is continuously replenished. However, the molecular mechanisms underlying these processes are not fully understood in the canine species. We addressed this in this study by analysing the expression of specific markers in spermatogonia of seminiferous tubules of canine testes. SSCs at different stages of reproductive development (prepubertal and adult) were examined by immunohistochemistry and flow cytometry. Glial cell-derived neurotrophic factor family receptor alpha-1 (GFRA1), deleted in azoospermia-like (DAZL) and promyelocytic leukaemia zinc finger (PLZF) were expressed in SSCs, while stimulated by retinoic acid gene 8 (STRA8) was detected only in undifferentiated spermatogonia in prepubertal testis and differentiated spermatogonia and spermatocytes in adult canine. Octamer-binding transcription factor 4 (OCT4) showed an expression pattern, and the levels did not differ between the groups examined. However, C-kit expression varied as a function of reproductive developmental stage. Our results demonstrate that these proteins play critical roles in the self-renewal and differentiation of SSCs and can serve as markers to identify canine spermatogonia at specific stages of development.

Relação entre a quantidade de AgNORS, atividade proliferativa e o estágio de desenvolvimento placentário em equinos

The Nucleolar Organizer Regions (NORs - nucleolar organizer regions) are used to describe regions of chromatin stained with silver nitrate and are related to the activity of rRNA synthesis and to the agility and speed of cell proliferation in the tissues studied. The objective of this study was to relate the amount of AgNORs, proliferative activity and stage of pregnancy in horses, using the coloring of Silver Nitrate. The embryonic attachments were collected, fixed in 10% buffered formaldehyde, embedded in paraplast and stained by silver nitrate. The groups were determined according to the gestational age. The amount of the corium NOR found in early pregnancy indicates the onset of cell activity, and in that the pregnancy progresses, the amount of NOR increases, suggesting higher activity and increased synthesis of their importance in maintaining the fetus. Contrary to what occurs in the corium, the quantification of NORs was higher in late pregnancy than in the beginning, suggesting the stabilization of these membranes in late pregnancy. The chorionic girdle and the yolk sac were found in early pregnancy and had lots of NORs, suggesting synthesis function and proliferation in early pregnancy, since their functions is maintenance of the embryo until the complete formation of the true placenta (chorio-allantoic membranes). We conclude that the membranes that develop in a progressive manner in accordance with the growing embryo/fetal (chorion, amnion and allantoic membranes) have an increased number of NORs and the membranes that involute after the formation of the embryo/fetus (yolk sac and chorionic girdle) have a decrease in number, suggesting a reduction in proliferative activity in these membranes.

Análise proliferativa nas células trofoblásticas em bovinos

The aim of the present study was to evaluate the cell proliferative activity, by AgNORs number, in different regions of bovine placenta throughout gestation. A total of 28 bovine placentas were separated into four groups: group I (60 to 120 days), group II (121 to 170 days), group III (171 to 220 days), and group IV (221 to 290 days). It was found a greater number of AgNORs in giant trophoblastic cells (GTC) when compared with mononuclear trophoblastic cells (MTC) (p<0,001) in all regions and gestational groups analyzed, that confirms their intensive synthesis activity in trophoblast epithelium. The central region of the placentome begins an intense proliferative activity in group II, observed by clusters, while placentomes edges showed a higher number of clusters on group III. These data suggest that the central region of the placentomes began an intense proliferative activity prior to its edge, both declines at the end of pregnancy. Interplacentomal area showed a higher number of AgNORs in the group IV, suggesting a higher proliferative activity of these cells at the end of pregnancy. The results of this study indicate that the proliferative activity, as determined by the amount of intranuclear AgNORs, exhibits patterns that are not only specific to each type of trophoblastic cells, but also for each specific region of bovine placenta throughout pregnancy.