Follicle-Stimulating Hormone Accelerates Mouse Oocyte Development In Vivo1

Abstract

During folliculogenesis, oocytes grow and acquire developmental competence in a mutually dependent relationship with their adjacent somatic cells. Follicle-stimulating hormone (FSH) plays an essential and well-established role in the differentiation of somatic follicular cells, but its function in the development of the oocyte has still not been elucidated. We report here that oocytes of Fshb(-/-) mice, which cannot produce FSH, grow at the same rate and reach the same size as those of wild-type mice. Consistent with this observation, the granulosa cells of Fshb(-/-) mice express the normal quantity of mRNA encoding Kit ligand, which has been implicated in oocyte growth. Oocytes of Fshb(-/-) mice also accumulate normal quantities of cyclin B1 and CDK1 proteins and mitochondrial DNA. Moreover, they acquire the ability to complete meiotic maturation in vitro and undergo transition from non-surrounded nucleolus to surrounded nucleolus. However, these events of late oocyte development are significantly delayed. Following in vitro maturation and fertilization, only a small number of embryos derived from oocytes of Fshb(-/-) mice reach the blastocyst stage. Administration of equine chorionic gonadotropin, which provides FSH activity, 48 h before in vitro maturation increases the number of blastocysts obtained subsequently. These results indicate that FSH is not absolutely required for oocyte development in vivo but that this process occurs more rapidly in its presence. We suggest that FSH may coordinate the development of the germline and somatic compartments of the follicle, ensuring that ovulation releases a developmentally competent egg.

Follicle-stimulating hormone regulates expression and activity of epidermal growth factor receptor in the murine ovarian follicle

“…Nonetheless, there is little or no effect on the expression of GC genes not regulated by FSH (31), and the follicles retain the ability to support the development of fully grown meiotically competent oocytes and to maintain them in prophase arrest (36). Although the oocytes can mature in vitro, they develop poorly after fertilization, indicating that some aspect of their development is abnormal (31,36). Fshb +/− females are fertile (31,36) and served as controls in our experiments.…”

“…By coordinating receptor expression and ligand release, FSH endows fully grown follicles with the capacity to activate EGFR signaling at ovulation. (35,36). Nonetheless, there is little or no effect on the expression of GC genes not regulated by FSH (31), and the follicles retain the ability to support the development of fully grown meiotically competent oocytes and to maintain them in prophase arrest (36).…”

“…Although the oocytes can mature in vitro, they develop poorly after fertilization, indicating that some aspect of their development is abnormal (31,36). Fshb +/− females are fertile (31,36) and served as controls in our experiments. Because the absence of FSH eventually leads to follicular atresia (37), we used prepubertal Fshb −/− females so that we could study the large cohort of follicles that initiates growth shortly after birth in the mouse, reaching full size after about 3 wk.…”

“…1A). Although growing follicles of Fshb −/− females do not form large antra (35,36), we were able to puncture the largest follicles and recover oocytes enclosed by GCs, which we provisionally term "COCs." In contrast to the COCs of Fshb +/− females, COCs from Fshb −/− females of the same age did not expand in response to EGF (Fig.…”

Rapid Genotyping of Animals Followed by Establishing Primary Cultures of Brain Neurons

“…The number of specimens can be scaled up (e.g., 96 samples) yet processed easily and simultaneously. Also the specimen type is not limited to tail clips; other sample types that could be used include ear punches, toe clippings, whole early embryos, and placenta tissues [2][3][4]29,30 . Different animal species can also be used.…”