The acrosomic reaction in stallion spermatozoa: inductive effect of the mare preovulatory follicular fluid

In the female genital tract, spermatozoa must undergo capacitation and acrosome reaction prior to fertilization. A number of factors may induce physiological acrosome reaction assayed in vitro. The aims of this study are to determine the inductive effect of the preovulatory follicular fluid on the sperm acrosomal status in the equine, once some characteristics of the follicular fluid during folliculogenesis had been evaluated. The spermatozoa were obtained from cauda epididymes of adult stallion. Follicular fluid was taken from mare ovarian follicles classified according to their diameter. In these fluids, total protein, progesterone, estradiol and osmolarity were determined. Afterwards, the effect of preovulatory follicular fluid (50) upon induction of the acrosomic reaction in stallion capacitated spermatozoa was assayed. Results show that during folliculogenesis the ratio progesterone/estrogen is below 1. In large preovulatory follicles, there is a sharp increase of progesterone, reaching a ratio progesterone/estrogen close to 4. Protein concentration and osmolarity increase together with follicular development, being osmolarity very high at the preovulatory stage. Follicular fluid--in vitro--increases the percentage of spermatozoa with acrosome reaction, maintaining high rates of vitality and motility. The characteristics of follicular fluid undergo dynamic changes during the folliculogenesis, such as steroid level, protein concentration and osmolarity. These events may play a role in the reproductive process in vivo, considering that in vitro the follicular fluid is a very effective inductor of the acrosome reaction, with optimum levels of vitality and motility.

Genesis y uso del termino pre-embrion en la literatura cientifica actual / Present use of the term pre-embryo

Durante estos últimos años el debate sobre el carácter humana del embrión ha continuado. Uno de los hechos que pueden percibirse en este debate, contrariamente a lo que sucedió en los primeros anos, es el olvido sistemático de la palabra ®pre-embrión¼ para referirse al embrión preimplantatorio. En este trabajo, tras analizar el nacimiento de esta palabra y los intentos de dotarla de una conceptualización adecuada, describimos y constatamos mediante un sencillo estudio bibliométrico el poco éxito que ha tenido esta palabra así como el estancamiento de esta desde su aparición. En conclusión, no sólo se puede certificar la carencia conceptual de éste término, es decir, su no correspondencia con realidad alguna, sino también certificar a nivel fenomenológico el escaso uso de ella, con lo que también se avala el carácter artificial del término.