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Biomedical subjects

R A Bowen

Publications and source records attributed to R A Bowen.

6 recordsLinked to original sources
PubMed1978

Embryo transfer for cows with reproductive problems.

Surgical embryo recovery and transfer methods were applied to 25 cows and heifers with chronic reproductive problems. In 16 of the 25 animals, abnormalities could not be detected by palpation per rectum and, at laparotomy, the probable cause of low fertility was found to be oviductal obstructions or periovarian adhesions in 6 of them. Four pregnancies were obtained from 3 of these 6 animals. A definitive diagnosis was not obtained through laparotomy in the other 10 animals in this group; however, an abnormal uterine environment associated with senescence may have been responsible for low fertility in the older cows. Eighteen calves were obtained by embryo transfer from 8 of these 10 donor animals. The remaining 9 heifers and cows had lesions detectable by palpation per rectum. Chronic, purulent metritis was found in 2 cows, one of which produced 7 calves by embryo transfer. The other 7 had periovarian adhesions, and 8 calves were obtained from 2 of them. The adhesions in 6 of these 7 cows were attributable to cesarean section. Laparotomy was valuable for defining the extent of the adhesions and establishing a reliable prognosis in some cases.

Animals↗
PubMed1978

Mechanisms of infertility in genital tract infections due to Chlamydia psittaci transmitted through contaminated semen.

Ten heifers inseminated with semen artificially contaminated with Chlamydia psittaci were not pregnant 40 days later, whereas five of 10 control heifers inseminated with the same semen mixed with control diluent became pregnant. Normal embryos were recovered two and one-half or three days after insemination of another group of animals with semen containing C. psittaci, a finding indicating that fertilization failure was not responsible for the infertility. Uterine biopsy samples taken from two heifers in this group contained scattered Chlamydia-infected cells that were detected by immunofluorescence in the subepithelial tissues of the uterine horns. This finding suggests that the infertility may result from an alteration in the uterine environment caused by multiplication of C. psittaci.

Animals↗
PubMed1976

In vitro fertilization, culture, and transfer of rabbit ova.

Ovulated rabbit oocytes were fertilized in vitro in chemically defined media supplemented with bovine serum albumin and either cultured up to the expanding blastocyst stage or transferred to recipients after varying periods of culture. Embryos transferred after up to 72 hours of in vitro culture were born as viable young. Oocytes from young virgin does were superior to oocytes from nonvirgin does for the purpose of in vitro fertilization (54% versus 26% fertilized, P less than 0.01). Capacitated sperm from artificially inseminated capacitators resulted in fertilization rates slightly lower than those from naturally mated does (46% versus 57% fertilized, P less than 0.025). Removal of cumulus and corona cells from oocytes with hyaluronidase and repeated aspiration through a fine pipette resulted in lowered fertilization rates (51% versus 73%, P less than 0.025). Linbro Disposo Tray wells were as good as glass tissue-culture dishes for the in vitro mixing of gametes and were more convenient to use. Modified Ham's F10 medium was used to culture the in vitro-fertilized embryos. However, when a modified Brackett's medium was used instead of modified Ham's F10 for the initial 4-hour period after mixing gametes, more oocytes were fertilized (52% versus 28%, P less than 0.01).

Animals↗