Evaluation of apoptosis as a mechanism of follicular cell atresia in the ovaries of cattle (bos indicus) and buffalo (bubalus bubalis) fetuses

The objective of this study was to investigate the occurrence of apoptosis in the ovaries of cattle and buffalo fetuses between 4 and 8 months old by the terminal deoxynucleotidyltransferase - mediated dUTP nick end labeling (TUNEL) assay . Histological analysis of the ovarian t issue showed that apoptosis occurred at all ages evaluated , presenting a similar pattern among different fetal stages in both species . Within species, secondary follicles displayed a higher (P 0.05) of apoptotic follicular cells among the three follicular classes compared . C omparing resul ts between species, secondary follicles had a higher (P < 0.05) mean number of TUN EL positive cells in bovine fetuses; however , this difference was proportional to the larger number of follicular cells present in secondary follicles in this species . In summary, the TUNEL method was effective for the detection of apoptosis in the support ing cells of ovarian follicles from bovine and buffalo fetuses with apoptosis occurring at similar rates in both species between 4 and 8 months of gestational age. Further studies are needed to better understand the dynamics of apoptosis as a regulator of follicular atresia in fetal ovaries from these species, as well as the potential involvement of the oocyte in this process.

Morphological and morphometric aspects of Crassostrea rhizophorae (Guilding, 1828) oocytes in three stages of the gonadal cycle / Aspectos Morfológicos y Morfométricos de Oocitos de Crassostrea rhizophorae (Guilding, 1828) en Tres Fases del Ciclo Gonadal

Crassostrea rhizophorae (Guilding, 1828) es una de las especies de ostras tropicales cultivadas en la costa brasilera, que presenta alto valor comercial, no existiendo información sobre las características gonadales, durante las fases reproductivas de esta especie. El objetivo de este trabajo fue analizar la morfología de los ovocitos y de los folículos gonadales de Crassostrea rhizophorae, en tres fases del ciclo gonadal. Analizando los cortes histológicos de las gónadas y considerando los ovocitos que presentaban núcleo y nucléolo evidentes, fueron determinadas tres fases del ciclo gonadal: gametogénesis inicial, crecimiento y maduración. En la fase de gametogénesis inicial, el diámetro de los folículos y de los ovocitos era de 180,29 (+ - 41,91) e 18,66 (+ - 6,85) µm, respectivamente; también identificamos gran cantidad de tejido conjuntivo interfolicular y un número mayor de ovocitos previtelogénicos. En la fase de crecimiento, el diámetro de los folículos y de los ovocitos era de 218,02 (+ - 43,19) y 25,92 (+ - 9,94) µm, respectivamente. Este fase fue caracterizada por una pequeña cantidad de tejido conjuntivo interfolicular y predominio de ovocitos vitelogénicos. En la fase de maduración, el diámetro de los folículos y de los ovocitos era de 298,16 ( + - 99,24) y 35,27 (+ - 6,2) µm, respectivamente, existiendo gran número de ovocitos maduros. De esta manera, concluimos que durante la implantación del cultivo, Crassostrea rhizophorae tolera la influencia de los factores intrínsecos y extrínsecos y no presenta alteraciones significativas en su actividad reproductiva.

Crassostrea rhizophorae (Guilding, 1828) is one of the tropical species of oysters cultivated on the Brazilian shore. Despite its high commercial value, there is no information on the gonadal characteristics during the reproductive stages of this species. The objective of this work was to analyze the morphology and morphometry of Crassostrea rhizophorae oocytes and follicles in three stages of the gonadal cycle. Were analized histological sections of gonads considering that the oocytes presented visible nuclei and nucleoli, it was observed three gonadal cycle stages: early gametogenesis, growth and maturation. In the early gametogenesis stage, follicles and oocytes presented diameters of 180.29 (± 41.91) and 18.66 (± 6.85) µm, respectively, and presence of large amount of connective tissue and previtellogenic oocyte. In the growth stage, follicles and oocytes presented diameters of 218.02 (± 43.19) and 25.92 (± 9.94) µm, respectively, this stage was characterized by a small amount of interfollicular connective tissue with vitellogenic oocyte predominate. In the maturation stage, follicles and oocytes presented diameters of 298.16 (± 99.24) and 35.27 (± 6.2) µm, respectively, and presence of large number of mature oocytes. We concluded that during culture Crassostrea rhizophorae tolerates the influence of intrinsic and extrinsic factors and does not undergo significant changes in reproductive activity.