Comparative ultrastructure of hatched human, mouse and bovine blastocysts

Abstract

A hatched human blastocyst obtained after in-vitro fertilization and culture was examined by transmission electron microscopy and the ultrastructural features compared with hatched mouse and bovine blastocysts. The human blastocyst contained a continuous layer of trophoblast cells with apical junctional complexes, an inner cell mass and the beginning of a primitive endoderm layer. Certain ultrastructural features were common to the blastocysts of all 3 species; these included characteristic junction regions between adjacent trophoblast cells, an abundance of microvilli on the external surfaces of the blastocysts and the presence of well developed mitochondria and numerous ribosomes in the trophoblast cells. The features that were dissimilar included the extent of development of the endoderm layer, the appearance of the inner cell mass and the nature and extent of vesicular inclusions in the trophoblast cells.

Bovine conceptus of Bos indicus produced by somatic cell nuclear transfer and parthenogenesis present morphological variations since the blastocyst stage

“…In contrast, IVF embryos showed few changes at the microscopic level, exhibiting morphology similar to embryos produced by natural mating. These findings corroborate other studies (Calarco and McLaren, 1976;Massip et al, 1981;Mohr and Trounson, 1982;Plante and King, 1994;Talbot et al, 2000;Maddox-Hyttel et al, 2003;), which also analyzed the morphology of these types of embryos. However, ours was a pioneer study in comparing D7 embryos produced via the tree techniques discussed.…”

“…This differentiation has been confirmed in other studies, which indicate that each cell group -trophectoderm, ICM, hypoblast or epiblast -has a specific role in embryonic development (Mohr and Trounson, 1982;Talbot et al, 2000).…”

“…Using light and transmission electron microscopy, this study described the morphology of bovine embryos derived from in vitro production techniques, and we inferred that the general morphology of these embryos did not differ from that found in other mammalian embryos, such as humans, rats, and sheep (Mohr and Trounson, 1982;Calarco and McLaren, 1976). However, several differences at the microscopic level could be observed when comparing the embryos with each other.…”

“…However, cases of malformation beginning in the earliest stages of pregnancy have also been found (Mohr and Trounson, 1982;Camargo et al, 2005). This occurs mainly in embryos produced by IVF, somatic cell nuclear transfer (SCNT) and parthenogenesis.…”

Glucose utilization and the PI3-K pathway: mechanisms for cell survival in preimplantation embryos

“…In addition, agents such as staurosporine do induce apoptosis very early during development (Weil et al 1996, Matwee et al 2000. In mammalian development, apoptosis normally occurs at the blastocyst stage and arises in both the ICM and TE (Mohr & Trounson 1982, Handyside & Hunter 1986, Brison & Schultz 1997, Jurisicova et al 1998. During this stage of development, one purpose of programmed cell death may be to eliminate cells with TE potential from the ICM (Pierce et al 1989).…”