Ultrastructural Study of the Early Development of the Sheep Embryo

Ferrer, Fernando J.; Garcia, C.; Villar, J. M.; Arias, María Elena

doi:10.1111/j.1439-0264.1995.tb00034.x

Cited by 12 publications

(22 citation statements)

References 24 publications

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“…Before the late morula stage, the cristae are sparse and lamelliform. This has been reported for the sea urchin (Berg and Long, 1964), wasp (Amy, 1975), pig (Hytell and Niemann, 1990), sheep (Ferrer et al, 1995;Calarco and McLaren, 1976), monkey (Enders and Schlafke, 1981), and human (Trounson and Sathananthan, 1984;Sundstrom et al, 1981). For the late morula through neural tube closure, the immature delamellated stage has been observed in the chick (dePaz et al, 1986;Bancroft and Bellars, 1975;Kowazaki and Hiruma, 1994), rat (Mackler et al, 1971;Takeuchi, 1980;Merker, 1970;Yang et al, 1995), and rabbit (Anderson et al, 1997;Sordhal et al, 1972).…”

Section: Discussionmentioning

confidence: 57%

Ultrastructural study of mitochondria and their cristae in embryonic rats and primate (N. nemistrina)

1998

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Information on the morphology of mitochondria during embryogenesis is scattered in the literature but there appears to be a developmental pattern characterized by vesiculation of the mitochondrial cristae. During early organogenesis, the embryo is in a relative state of hypoxia and this is associated with decrease of terminal electron transport system activity and a marked increase in glycolysis. Ultrastructural studies of a 14 somite monkey embryo, and day 10 and 12 rat embryos, along with a review of the literature led us to determine that this hypoxic stage is characterized by vesiculation of the mitochondrial cristae. Starting in the late morula stage and continuing during early postimplantation embryogenesis the cristae increase and appear tubular or vesicular. After the end of neurulation, and with onset of vascular perfusion, the cristae gradually become lamellated and by the limb bud stage appear more mature. We suggest that new cristae form from blebs of the inner mitochondrial membrane and that subsequently with maturation these blebs collapse giving them a lamelliform appearance. The delamellated state of the cristae may protect the embryo from toxic respiratory end-products of oxidative respiration which could accumulate in an embryo lacking vascular perfusion. In the heart of monkey and rat embryos, the mitochondria had diameters which were approximately twice those found in skin and neural tube. Anat.

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Section: Discussionmentioning

confidence: 57%

Ultrastructural study of mitochondria and their cristae in embryonic rats and primate (N. nemistrina)

1998

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“…In this paper we investigate differences in ultrastructure between frozenthawed ovine embryos cryopreserved with either ethylene glycol or glycerol in comparison to the ultrastructure of fresh embryos as controls. Although the ultrastructural characteristics of fresh embryos have already been reported [11,12], this is to our knowledge the first time that ovine frozen-thawed embryos have been evaluated at the electron microscopic level.…”

Section: Discussionmentioning

confidence: 99%

“…Injuries or anomalies detected at this level, but not with conventional light microscopy, could account for the loss of viability found after transfer. Ultrastructure of fresh sheep embryos has been studied before [11,12], but as far as we know, this is the first report showing an ultrastructural analysis of frozen-thawed sheep embryos.…”

Section: Introductionmentioning

confidence: 97%

Ultrastructural Characteristics of Fresh and Frozen-Thawed Ovine Embryos Using Two Cryoprotectants1

Cocero

Espina

Aguilar

2002

Biology of Reproduction

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Cryopreservation of sheep embryos with ethylene glycol as a protectant appears to be more effective than glycerol, particularly at the morula stage, as has been demonstrated on the basis of in vitro and in vivo development rates after thawing. In this study we compare the ultrastructure of fresh morulae, thawed morulae, and blastocysts cryopreserved with either ethylene glycol or glycerol at the electron microscopic level, to look for cellular damage that could be responsible for proven differences in embryo survival after transfer. Embryos cryopreserved with glycerol showed unequal degrees of conservation even among blastomeres within a single embryo. In morulae, inner blastomeres were completely damaged, whereas external ones appeared to be intact. Both morulae and blastocysts cryopreserved with ethylene glycol showed a higher uniformity in blastomere conservation than embryos with glycerol. The most remarkable features in this experimental group were the presence of desmosomes following tight junctions between blastomeres and the presence of many microvilli on the outer surface of external blastomeres. These characteristics are similar in fresh embryos of the control group. Our results show that ethylene glycol protects membrane and cytoplasmic structures of embryonic cells from cryoinjury much better than glycerol. In vivo survival of embryos confirmed the ultrastructural observations. A limited permeability of glycerol would explain the observed ultrastructural differences in blastomere integrity, which depends on blastomere location and the differences between morulae and blastocysts. We conclude that the low reproductive yield after cryopreservation using glycerol can be attributed to the lack of protection of inner cells. early development, embryo, pregnancy, reproductive technology, trophoblast

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“…Cytoplasmic vacuoles are present in bovine [34,35] and ovine [49] embryos produced in vivo and become fewer in number as development progresses. However, the functional capacity of these vacuoles within embryonic cells remains unknown.…”

Section: Effects Of Treatment On Blastocyst Ultrastructurementioning

confidence: 99%

Ultrastructural Morphometry of Bovine Blastocysts Produced In Vivo or In Vitro1

Crosier

Farin

Dykstra

et al. 2001

Biology of Reproduction

151

100

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The objective of this study was to compare the ultrastructure of bovine blastocysts produced in vivo or in vitro by using morphometric analysis. Blastocysts produced in vivo (multiple ovulations, MO) were obtained from superovulated Holstein cows. For blastocysts produced in vitro, cumulus-oocyte complexes aspirated from ovaries of Holstein cows were matured and fertilized in vitro. At 20 h postinsemination (hpi), zygotes were distributed into one of three culture media: 1) IVPS (in vitro produced with serum): TCM-199 + 10% estrous cow serum (ECS); 2) IVPSR (in vitro produced with serum restriction): TCM-199 + 1% BSA until 72 hpi, followed by TCM-199 + 10% ECS from 72 to 168 hpi; and 3) mSOF (modified synthetic oviductal fluid): mSOF + 0.6% BSA. At 168 hpi, six or seven grade 1 blastocysts from each of the four treatments (MO, IVPS, IVPSR, and mSOF) were fixed and prepared for transmission electron microscopy. Random micrographs of each blastocyst were used to determine the volume density of cellular components. Overall, as blastocysts progressed in development, the volume densities of cytoplasm and intercellular space decreased (P < 0.05) and the volume densities of mature mitochondria, nuclei, blastocoele, and apoptotic bodies increased (P < 0.05). Across treatments, the proportional volumes of nuclei and inclusion bodies were increased in inner cell mass cells compared with trophectoderm cells for mid- and expanded blastocysts. For blastocysts produced in vitro, the volume density of mitochondria was decreased (P < 0.05) as compared with that of blastocycts produced in vivo. The proportional volume of vacuoles was increased (P < 0.05) in blastocysts from the mSOF treatment as compared with blastocysts produced in vivo. For mid- and expanded blastocysts from all three in vitro treatments, the volume density of lipid increased (P < 0.05) and the volume density of nuclei decreased (P < 0.05) compared with those of blastocysts produced in vivo. In conclusion, blastocysts produced in vitro possessed deviations in volume densities of organelles associated with cellular metabolism as well as deviations associated with altered embryonic differentiation. However, the specific nature of these deviations varied with the type of culture conditions used for in vitro embryo production.

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Ultrastructural Study of the Early Development of the Sheep Embryo

Cited by 12 publications

References 24 publications

Ultrastructural study of mitochondria and their cristae in embryonic rats and primate (N. nemistrina)

Ultrastructural study of mitochondria and their cristae in embryonic rats and primate (N. nemistrina)

Ultrastructural Characteristics of Fresh and Frozen-Thawed Ovine Embryos Using Two Cryoprotectants1

Ultrastructural Morphometry of Bovine Blastocysts Produced In Vivo or In Vitro1

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