Immunolocalization of activin and inhibin at different stages of follicular development in the lizard Sceloporus torquatus.

The activins and inhibins are glycoproteins with a role in the follicular development of vertebrates, that are found in follicular fluid and somatic follicular cells, with a different pattern among taxa. The principal function of activin (Act) is to modulate the follicle-stimulating hormone (FSH) synthesis and secretion, whereas inhibin (Inh) downregulates it. Both factors are modulators of intraovarian follicular recruitment, oocyte maturation, cell proliferation, and steroidogenic activity. Our aim was to characterize the immunolocalization of Act and Inh in the ovarian follicles during the reproductive cycle of the lizard Sceloporus torquatus. Act was detected in the granulosa cells and oocyte cortex in the different stages of follicular development. On the other hand, we identified Inh in the oocyte cortex and the cytoplasm of pyriform and small cells of previtellogenic follicles. Also, we found immunoreactivity in the oocyte cortex, theca, and small cells of vitellogenic and preovulatory follicles. Our data provide evidence that Act and Inh have changes related to the stage of follicular development. This dynamic appears to be conserved among vertebrates and is fundamental to ensure an adequate follicular development in this specie.

[Cytokines and growth factors as autocrine and paracrine modulators in the peri-implantation period]. / Las citocinas y los factores de crecimiento como reguladores autocrinos y paracrinos durante el periodo peri-implantacional.

The embryo implantation is a complex event that involve a interactions sequence among conceptus and uterine endometrium. Several cytokines and growth factors participate as autocrine/paracrine modulators in such interrelations. In this paper the role and expression and functions of cytokines and growth factors in early pregnancy are analyzed. Post-coito expression of cytokines in uterine cells and leukocytes promoting a uterine inflammatory response to semen. The growth factors are expressed in early pregnancy for several uterine tissues. The ovarian steroid hormones modulate the synthesis and secretion of this molecules in uterus. Autocrine and paracrine regulation are require for embryo implantation. At least interleukin-1, leukemia inhibitor factor and epidermal growth factor receptor are indispensable to mice embryo implantation.

[Regulation of uterine cellular proliferation with estrogens and growth factors]. / Regulación de la proliferación celular uterina por estrógenos y factores de crecimiento.

In this paper the role of estrogen and growth factors in the uterine cellular proliferation is analyzed. The evidences indicate that the estradiol-stimulate cell division is associated with the induction of expression of a variety of growth factors from the all major uterine cell types (epithelia, stroma and myometrium). These growth factors amplify the estrogen proliferation signal in autocrine and/or paracrin fashion. The best-studied growth factors in the uterine response to estradiol are epidermal growth factor (EGF) and insulin-like growth factor (IGF-1). Uterine cell proliferation is a complex process that involves interactions of several growth factors, ovarian steroids hormones action and cell to cell signaling.