TY - JOUR

T1 - Post-hatching development of the porcine and bovine embryo-defining criteria for expected development in vivo and in vitro

AU - Vejlsted, Morten

AU - Du, Yutao

AU - Vajta, Gábor

AU - Maddox-Hyttel, Poul

PY - 2006

Y1 - 2006

N2 - Particular attention has been paid to the pre-hatching period of embryonic development although blastocyst development is a poor indicator of embryo viability. Post-hatching embryonic dev elopment in vitro would allow for establishment of more accurate tools for evaluating developmental potential without the need for transfer to recipient animals. Such a system would require (1) definition of milestones of expected post-hatching embryonic development in vivo; and (2) development of adequate culture systems. We propose a stereomicroscopical staging system for post-hatching embryos defining the following stages: (1)Expanded hatched blastocyst stage where the embryo presents an inner cell mass (ICM) covered by trophoblast. (2) Pre-streak stage 1 where the embryonic disc is formed. (3) Pre-streak stage 2 where a crescent-shaped thickening of the caudal portion of the embryonic disk appears. (4) Primitive streak stage where the primitive streak has developed as an axis of cell ingression of cells for meso- and endoderm formation. (5) Neural groove stage where the neural groove is developing from the rostral pole of the embryo along with a proportional shortening of the primitive streak; and (6) Somite stage(s) where paraxial mesoderm gradually condensates to form somites. Post-hatching development of bovine embryos in vitro is compromised and although hatching occurs and elongation can be physically provoked by culture in agarose tunnels, the embryonic disk characterizing the pre-streak stage 1 is never established. Thus, particular focus should be placed on establishing culture conditions that support at least some of the above-mentioned critical phases of development that in vivo occur within the initial two (pig) to three (cattle) weeks.

AB - Particular attention has been paid to the pre-hatching period of embryonic development although blastocyst development is a poor indicator of embryo viability. Post-hatching embryonic dev elopment in vitro would allow for establishment of more accurate tools for evaluating developmental potential without the need for transfer to recipient animals. Such a system would require (1) definition of milestones of expected post-hatching embryonic development in vivo; and (2) development of adequate culture systems. We propose a stereomicroscopical staging system for post-hatching embryos defining the following stages: (1)Expanded hatched blastocyst stage where the embryo presents an inner cell mass (ICM) covered by trophoblast. (2) Pre-streak stage 1 where the embryonic disc is formed. (3) Pre-streak stage 2 where a crescent-shaped thickening of the caudal portion of the embryonic disk appears. (4) Primitive streak stage where the primitive streak has developed as an axis of cell ingression of cells for meso- and endoderm formation. (5) Neural groove stage where the neural groove is developing from the rostral pole of the embryo along with a proportional shortening of the primitive streak; and (6) Somite stage(s) where paraxial mesoderm gradually condensates to form somites. Post-hatching development of bovine embryos in vitro is compromised and although hatching occurs and elongation can be physically provoked by culture in agarose tunnels, the embryonic disk characterizing the pre-streak stage 1 is never established. Thus, particular focus should be placed on establishing culture conditions that support at least some of the above-mentioned critical phases of development that in vivo occur within the initial two (pig) to three (cattle) weeks.

KW - Former LIFE faculty

KW - Bovine

KW - Porcine

KW - Embryo

KW - Post-hatching

KW - Gastrulation

KW - Staging

KW - Development

U2 - 10.1016/j.theriogenology.2005.09.021

DO - 10.1016/j.theriogenology.2005.09.021

M3 - Journal article

VL - 65

SP - 153

EP - 165

JO - Theriogenology

JF - Theriogenology

SN - 0093-691X

IS - 1

ER -