title: Ovulated oocytes collected from PMSG/hCG-treated and cycling Djungarian or Siberian hamsters (Phodopus sungorus) are structurally similar with no evidence of polar body formation, indicating arrest in meiosis I.
abstract: This study was undertaken (1) to devise a method of inducing multiple follicular development and subsequent ovulation in the Djungarian or Siberian hamster (Phodopus sungorus) and (2) to assess the quality of ovulated oocytes collected from PMSG/hCG treated animals in comparison to naturally ovulating animals. Hamsters (4-5 weeks; n = 70) received 5 IU PMSG followed 50-52 hr later by 10 IU hCG. Ovulated oocytes were collected 14-20 hr after hCG injection. Ovulated oocytes were flushed from oviducts of cycling animals (7-12 weeks; n = 30) exhibiting two consecutive estrous cycles. Oocytes were fixed and subjected to triple fluorescence immunostaining using anti-tubulin antibodies, fluorescein phalloidin, and Hoechst 33258. The mean number of ovulated oocytes collected from cycling animals was 4.8 +/- 0.4 (range 1-7). Ovulation occurred in 73% of the PMSG/hCG-stimulated animals. The mean number of oocytes ovulated from stimulated animals was 9.2 +/- 0.8 (range 0-22). The ovaries of animals that did not ovulate or that ovulated few oocytes did respond to PMSG, as indicated by the presence of multiple follicular development and pre-ovulatory stigmata. There was no evidence of a polar body in ovulated oocytes collected from PMSG/hCG-treated or cycling animals, indicating that oocytes were arrested in meiosis I. In the majority (80%) of ovulated oocytes from PMSG/hCG-treated and cycling animals, cortically placed chromosomes were aligned on a metaphase plate equidistant from a bipolar spindle. Sparse f-actin staining was observed in the region of the ooplasm surrounding the chromosomes.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Anatomy and Cellular Biology, Tufts University, School of Veterinary Medicine, Boston, Massachusetts 02111, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Murray
authors.forename: S L
authors.initials: SL
authors.lastname: Laprise
mesh_terms: D000818:Animals; D006224:Cricetinae; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology*; D006801:Humans; D008540:Meiosis; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010060:Ovulation / Q000502:physiology*; D017111:Phodopus / Q000502:physiology*
chemical_list: D006064:Gonadotropins, Equine