Infertility is a known major health concern and is estimated to impact ~15% of couples in the U.S. The majority of failed pregnancies occur before or during implantation of the fertilized embryo into the uterus. Understanding the mechanisms regulating development by studying mouse reproductive organs could significantly contribute to an improved understanding of normal development of reproductive organs and developmental causes of infertility in humans. Towards this goal, we report a three-dimensional (3D) imaging study of the developing mouse reproductive organs (ovary, oviduct, and uterus) using optical coherence tomography (OCT). In our study, OCT was used for 3D imaging of reproductive organs without exogenous contrast agents and provides micro-scale spatial resolution. Experiments were conducted in vitro on mouse reproductive organs ranging from the embryonic day 14.5 to adult stages. Structural features of the ovary, oviduct, and uterus are presented. Additionally, a comparison with traditional histological analysis is illustrated. These results provide a basis for a wide range of infertility studies in mouse models. Through integration with traditional genetic and molecular biology approaches, this imaging method can improve understanding of ovary, oviduct, and uterus development and function, serving to further contribute to our understanding of fertility and infertility.
Since mouse is a superior model for genetic analysis of human disorders, reproductive studies in mice have significant
implications on further understanding of fertility and infertility in humans. Fertilized oocytes are transported through the
reproductive tract by motile cilia lining the lumen of the oviduct as well as by oviduct contractions. While the role of
cilia is well recognized, ciliary dynamics in the oviduct is not well understood, largely owing to the lack of live imaging
approaches. Here, we report in vivo micro-scale mapping of cilia and cilia beat frequency (CBF) in the mouse oviduct
using optical coherence tomography (OCT). This functional imaging method is based on spectral analysis of the OCT
speckle variations produced by the beat of cilia in the oviduct, which does not require exogenous contrast agents. Animal
procedures similar to the ones used for production of transgenic mice are utilized to expose the reproductive organs for
imaging in anesthetized females. In this paper, we first present in vivo structural imaging of the mouse oviduct capturing
the oocyte and the preimplantation embryo and then show the result of depth-resolved high-resolution CBF mapping in
the ampulla of the live mouse. These data indicate that this structural and functional OCT imaging approach can be a
useful tool for a variety of live investigations of mammalian reproduction and infertility.
Studying the dynamic events involved in early preimplantation embryo development during their transport from the ovary to the uterus is of great significance to improve the understanding of infertility, and eventually to help reduce the infertility rate. The mouse is a widely used mammalian model in reproductive biology, however, dynamic imaging studies of mouse preimplantation embryos have been very limited due to the lack of proper imaging tools for such analysis. Here, we introduce an innovative approach, which can potentially be used for three-dimensional imaging and tracking of murine oocytes with optical coherence tomography (OCT) as they exit the ovary and migrate through the oviduct to the uterus. The imaging is performed with spectral-domain OCT system operating at 70 kHz A-scan rate. The preimplantation embryos and surrounding cumulus cells can be clearly visualized. Results from our experiments indicate that OCT has great potential for dynamic imaging of the oviduct and oocyte tracking, which provides the foundation for future investigations aimed at understanding dynamic events during preimplantation stages in normal development as well as in mouse models of infertility.