Veterinary Archives, Vol. 86 No. 5, 2016.
Original scientific paper
The influence of follicle size on the developmental kinetics of bovine embryos.
Martina Lojkić
orcid.org/0000-0003-2718-3348
; Clinic for Reproduction and Obstetrics, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Sara Uvodić
; Postgraduate specialist student, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Iva Getz
; Clinic for Reproduction and Obstetrics, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Marko Samardžija
; Clinic for Reproduction and Obstetrics, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Jasna Aladrović
; Department of Physiology and Radiobiology, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Nino Maćešić
; Clinic for Reproduction and Obstetrics, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Tugomir Karadjole
; Clinic for Reproduction and Obstetrics, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Goran Bačić
; Clinic for Reproduction and Obstetrics, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
Mario Matković
; Center for Reproduction and Animals Breeding of Croatia, Križevci, Croatia
Miroslav Benić
; Croatian Veterinary Institute, Zagreb, Croatia
Abstract
The aim of the present study was to investigate the effect of follicle size on the kinetics of the first cleavage and subsequent blastocyst development of bovine embryos. Cumulus oocytes complexes (COCs), aspirated from small (≤5 mm) and large (>5 mm) follicles of abattoir-derived ovaries, were graded for their morphological appearance, and were cultured to assess their developmental competence. In order to study the kinetics of early cleavage, the number of cleaved embryos was recorded at 24, 27, 30, 33, 36 and 48 hours post insemination (hpi). Morula and blastocyst development was recorded on days 5, 6, 7 and 8. A rapid rise in the rate of cleaved embryos was observed by 27 hpi, for oocytes collected both from ≤5 mm and >5 mm follicles. However, oocytes recovered from follicles >5 mm cleaved in significantly higher proportion at 24 to 30 hpi, which was reflected in a higher overall cleavage rate at 48 hpi. The kinetics of early cleavage were consistent with the subsequent development of the embryos, that is, the oocytes from >5 mm follicles which completed the first cell division faster developed to morula stage on Day 5 and blastocyst stage on Days 6 and 7 in a higher proportion than oocytes from ≤5 mm follicles. The hatching rate on Day 9 was significantly higher when oocytes originated from >5 mm follicles. The total cell number was not affected by follicle size. The results showed that oocytes derived from >5 mm follicles displayed higher developmental competence than oocytes from ≤5 mm follicles, in terms of timing of first cleavage, timing of blastocyst development and overall blastocyst rate. The selection of oocytes based on follicle size and kinetics of cleavage could be useful tools in selecting the best embryos for transfer.
Keywords
oocyte; follicle size; developmental competence; cleavage; cow
Hrčak ID:
167412
URI
Publication date:
23.9.2016.
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