TY - JOUR
T1 - The ovulated ovum of the horse
T2 - cytology of nonfertilized ova to pronuclear stage ova.
AU - Enders, A. C.
AU - Liu, Irwin
AU - Bowers, J.
AU - Lantz, K. C.
AU - Schlafke, S.
AU - Suarez, S.
PY - 1987/1/1
Y1 - 1987/1/1
N2 - Fertilization and early development in the horse were studied by recovering oviductal ova at various times after postovulatory mating. Ova collected between 7 and 22 h post coitum (pc) were examined for evidence of fertilizing sperm, cellular changes accompanying fertilization, and pronuclear development. Five ova collected between 7 and 9 h pc contained a marginal metaphase plate, but had no indication of sperm components; three of these, however, showed reduced numbers of cortical granules. Two activated ova (10 and 14 h pc) were in telophase of the second meiotic division, following incorporation of the fertilizing sperm. The fertilizing sperm was situated in a slight elevation; the nucleus was expanding but lacked a nuclear envelope. The pronuclear stage in the horse began as early as 12 h pc, and lasted at least until 21 h pc. Sperm tail remnants were seen in 5 of 7 pronuclear-stage ova, although the crowding of the cytoplasm with clusters of lipid and vacuoles made discerning sperm tail remnants difficult. The spindles of the metaphase stage of the second meiotic division were oriented radially, that is, at right angles to the cell surface, in all but one ovum, so this orientation is not a response to fertilization.
AB - Fertilization and early development in the horse were studied by recovering oviductal ova at various times after postovulatory mating. Ova collected between 7 and 22 h post coitum (pc) were examined for evidence of fertilizing sperm, cellular changes accompanying fertilization, and pronuclear development. Five ova collected between 7 and 9 h pc contained a marginal metaphase plate, but had no indication of sperm components; three of these, however, showed reduced numbers of cortical granules. Two activated ova (10 and 14 h pc) were in telophase of the second meiotic division, following incorporation of the fertilizing sperm. The fertilizing sperm was situated in a slight elevation; the nucleus was expanding but lacked a nuclear envelope. The pronuclear stage in the horse began as early as 12 h pc, and lasted at least until 21 h pc. Sperm tail remnants were seen in 5 of 7 pronuclear-stage ova, although the crowding of the cytoplasm with clusters of lipid and vacuoles made discerning sperm tail remnants difficult. The spindles of the metaphase stage of the second meiotic division were oriented radially, that is, at right angles to the cell surface, in all but one ovum, so this orientation is not a response to fertilization.
UR - http://www.scopus.com/inward/record.url?scp=0023408381&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0023408381&partnerID=8YFLogxK
U2 - 10.1095/biolreprod37.2.453
DO - 10.1095/biolreprod37.2.453
M3 - Article
C2 - 3676399
AN - SCOPUS:0023408381
VL - 37
SP - 453
EP - 466
JO - Biology of Reproduction
JF - Biology of Reproduction
SN - 0006-3363
IS - 2
ER -