Oocyte‐activating capacity of fresh and frozen–thawed spermatids in the common marmoset (Callithrix jacchus)

• Published in: Molecular reproduction and development 2018-05, Vol.85 (5), p.376-386
• Main Authors: Ogonuki, Narumi, Inoue, Hiroki, Matoba, Shogo, Kurotaki, Yoko K., Kassai, Hidetoshi, Abe, Yukiko, Sasaki, Erika, Aiba, Atsu, Ogura, Atsuo
• Format: Article
• Language: English
• Subjects: Animals; Calcium Signaling; Calcium signalling; Callithrix; Callithrix jacchus; Cell Nucleus - metabolism; Cryopreservation; Cytoplasm; Female; fertilization; Fish; Gestation; Glycerol; ICSI; Injection; Male; Males; Meiosis; Mice; Microinjections; Microscopy; Nuclear Transfer Techniques; Nuclei; Nucleoli; oocyte activation; Oocytes; Oocytes - cytology; Oocytes - metabolism; Oscillations; Reproductive technologies; Reproductive technology; Spermatids; Spermatids - cytology; Spermatids - metabolism; spermiogenesis
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/mrd.22971

The common marmoset (Callithrix jacchus) represents a promising nonhuman primate model for the study of human diseases because of its small size, ease of handling, and availability of gene‐modified animals. Here, we aimed to devise reproductive technology for marmoset spermatid injection using immature males for a possible rapid generational turnover. Spermatids at each step could be identified easily by their morphology under differential interference microscopy: thus, early round spermatids had a round nucleus with a few nucleolus‐like structures and abundant cytoplasm, as in other mammals. The spermatids acquired oocyte‐activating capacity at the late round spermatid stage, as confirmed by the resumption of meiosis and Ca2+ oscillations upon injection into mouse oocytes. The spermatids could be cryopreserved efficiently with a simple medium containing glycerol and CELL BANKER®. Late round or elongated spermatids first appeared at 10–12 months of age, 6–8 months before sexual maturation. Marmoset oocytes microinjected with frozen–thawed late round or elongated spermatids retrieved from a 12‐month‐old male marmoset developed to the 8‐cell stage without the need for artificial oocyte activation stimulation. Thus, it might be possible to shorten the intergeneration time by spermatid injection, from 2 years (by natural mating) to 13–15 months including gestation.