Efficient Superovulation and Egg Collection from Mice

Miyuki Shindo; Kenji Miyado; Woojin Kang; Maki Fukami; Mami Miyado

doi:10.21769/BioProtoc.4439

Efficient Superovulation and Egg Collection from Mice

Bio Protoc. 2022 Jun 5;12(11):e4439. doi: 10.21769/BioProtoc.4439.

Authors

Miyuki Shindo¹, Kenji Miyado², Woojin Kang², Maki Fukami³, Mami Miyado^{3

4}

Affiliations

¹ Division of Laboratory Animal Resources, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo 157-8535, Japan.
² Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo 157-8535, Japan.
³ Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo 157-8535, Japan.
⁴ Department of Food and Nutrition, Beppu University, 82 Kita-Ishigaki, Beppu, Oita 874-8501, Japan.

Abstract

Superovulation is a method used to reduce the number of mice used per experiment by increasing the egg number. Conventionally, superovulation for obtaining mouse eggs involves the use of equine chorionic gonadotropin (eCG) for stimulation and human CG for induction. Female mice of the C57BL/6 inbred strain spontaneously ovulate approximately 10 eggs. The average number of eggs ovulated using the conventional superovulation method is approximately twice as high as that obtained by spontaneous ovulation. Here, we describe the conventional and non-conventional methods of intraperitoneal injection of superovulation reagents in mice and subsequent egg collection. The non-conventional superovulation method combining anti-inhibin serum (AIS) plus eCG for stimulation is more efficient than conventional superovulation. Appropriate intervals from each injection to sampling induce large numbers of high-quality eggs. Immediately after ovulation, eggs are surrounded by cumulus cells, forming an egg-cumulus complex. These cumulus cells are then removed from the egg-cumulus complex by treatment with hyaluronidase to obtain the exact number of eggs. This protocol is suitable for further manipulations such as intracytoplasmic sperm injection and cryopreservation of eggs, as well as for the analyses of responsivity to superovulation reagents in genetically modified mice obtained by genome editing.

Keywords: Anti-inhibin serum; Chorionic Gonadotropin; Cumulus cells; Egg; Hyaluronidase; Mouse; Oocyte; Superovulation.