Spermatozoa and spermatids retrieved from frozen reproductive organs or frozen whole bodies of male mice can produce normal offspring.
Cryopreservation of male germ cells is a strategy to conserve animal species and strains of animals valuable to biomedical research. We tested whether mouse male germ cells could be cryopreserved without cryoprotection by simply freezing epididymides, testes, or whole bodies. The reproductive organs were isolated from killed mice and frozen for 1 week to 1 year at -80 degrees C before spermatozoa and spermatids were collected and injected into mature oocytes. Normal pups were born irrespective of strains tested (ICR and C57BL/6). Epididymides and testes frozen and transported internationally to another laboratory by air could produce pups of inbred C57BL/6 mice. Testicular spermatozoa retrieved from the bodies of male mice (BALB/c nude and C3H/He strains) that had been kept frozen (-20 degrees C) for 15 years could also produce normal offspring by microinsemination. Thus, freezing of either male reproductive organs or whole bodies is the simplest way to preserve male germ cells. Restoration of extinct species could be possible if male individuals are found in permafrost.
Ogonuki
Narumi
N
Institute of Physical and Chemical Research RIKEN Bioresource Center, Tsukuba, Ibaraki 305-0074, Japan.
Mochida
Keiji
K
Miki
Hiromi
H
Inoue
Kimiko
K
Fray
Martin
M
Iwaki
Takamasa
T
Moriwaki
Kazuo
K
Obata
Yuichi
Y
Morozumi
Kazuto
K
Yanagimachi
Ryuzo
R
Ogura
Atsuo
A
D000818:Animals; D015925:Cryopreservation; D004622:Embryo, Mammalian / Q000196:embryology; D004822:Epididymis / Q000378:metabolism; D005260:Female; D005307:Fertilization in Vitro; D005615:Freezing; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009865:Oocytes / Q000378:metabolism; D012098:Reproduction / Q000502:physiology*; D013048:Specimen Handling; D013087:Spermatids / Q000166:cytology / Q000502:physiology*; D013696:Temperature; D013737:Testis / Q000166:cytology; D013997:Time Factors