title: Intracytoplasmic sperm injection of mouse oocytes with 5 mM Ca2+ at different intervals.
abstract: The objective of this investigation was to determine whether intracytoplasmic sperm injection (ICSI) can be performed in the mouse. Metaphase II oocytes were obtained from F1 hybrid mice (C57BL x CBA) by i.p. injections of 10 IU pregnant mare's serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) administered 48 h apart. Oocytes with cumulus oophorus were retrieved 13-14 h post HCG. Cumulus was dispersed with 0.1% hyaluronidase. Mouse spermatozoa were obtained from the cauda epididymides of males of the same strain. The spermatozoa were processed by the standard swim-up procedure. The harvested spermatozoa were then incubated for 1.5 h to allow capacitation. Healthy oocytes were injected with 3-4 pl 5 mM Ca2+, followed by one live morphologically normal spermatozoon into the cytoplasm at intervals of 0, 0.5, 1, 2 and 3 h. The proportion of 2-cell embryos that developed from oocytes injected with Ca2+ and spermatozoa ranged between 29.5 and 36.5% in all groups, with no statistical difference between treatments. Chromosomal analysis showed that two-thirds of the ICSI-derived 2-cell embryos were diploid. The proportion of parthenogenetically activated embryos in the ICSI groups was similar to that in the control group (8-10%) which was injected with Ca2+ and polyvinyl pyrrolidone only. The proportion of blastocysts that developed in culture from the ICSI-derived 2-cell embryos was of the order of 36-42%. Some blastocysts were used for cell number counts. There was a significant increase in total and inner cell mass counts of blastocysts in which the spermatozoon was injected at 2 and 3 h following Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Obstetrics and Gynaecology, National University of Singapore.
authors.forename: A
authors.initials: A
authors.lastname: Ahmadi
authors.forename: S C
authors.initials: SC
authors.lastname: Ng
authors.forename: S L
authors.initials: SL
authors.lastname: Liow
authors.forename: J
authors.initials: J
authors.lastname: Ali
authors.forename: A
authors.initials: A
authors.lastname: Bongso
authors.forename: S S
authors.initials: SS
authors.lastname: Ratnam
mesh_terms: D000818:Animals; D001723:Birth Rate; D002118:Calcium / Q000008:administration & dosage*; D003593:Cytoplasm; D004171:Diploidy; D004334:Drug Administration Schedule; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology; D005260:Female; D005306:Fertilization; D007267:Injections; D008297:Male; D051379:Mice; D009865:Oocytes; D009994:Osmolar Concentration; D013094:Spermatozoa
chemical_list: D002118:Calcium