title: Morphological aspects of in vivo cleavage in Myocastor coypus (coypu).
abstract: The objective of the present work was to characterize the in vivo cleavage stage of Myocastor coypus embryos. For this purpose a colpocytological follow-up and controlled mating of 18 females were performed. Specimens from the beginning of the first cleavage to the acquisition of a morula appearance were considered to be in cleavage stage. Embryos in cleavage were collected between days 3 and 6 post-coitus. Of the collected embryos, 80% presented an even number of blastomeres and the remaining 20% an odd number. Embryos from 3 to 7 cells were blastomere associations in a spherical disposition within the zona pellucida. Blastomeres were spherical or ovoid, presenting slight flattening in areas contacting with other blastomeres. Embryos of 8 and 9 cells were as a group of blastomeres slightly elongated, surrounded by a spherical zona pellucida. The percentage of peri-vitelline space occupied by the embryonic mass ranged from 74.1 to 95.8% for all the substages. The cleavage pattern, developed in the oviduct, was of a rotational holoblastic type and asynchronic.
authors.affiliation: Areas de Ciencias Morfológicas y de Reproducción, Núcleo FISFARVET, Facultad de Ciencias Veterinarias, UNCPBA, B7000GHG-Tandil, Buenos Aires, República Argentina. aefelipe@vet.unicen.edu.ar
authors.forename: A E
authors.initials: AE
authors.lastname: Felipe
authors.forename: M T
authors.initials: MT
authors.lastname: Teruel
authors.forename: J A
authors.initials: JA
authors.lastname: Cabodevila
authors.forename: S S
authors.initials: SS
authors.lastname: Callejas
mesh_terms: D000818:Animals; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D005314:Embryonic and Fetal Development; D005260:Female; D008297:Male; D009028:Morula / Q000502:physiology; D011247:Pregnancy; D012377:Rodentia / Q000196:embryology*