Applications of the SEM to the analysis of morphogenetic events

England, Marjorie A.

doi:10.1111/j.1365-2818.1981.tb01289.x

Cited by 13 publications

(5 citation statements)

References 34 publications

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“…ECM fibrils radiate radially from the chick primitive streak region (England, 1981). This radial organization appears to be the result of tension (Kucera and Monnet-Tschudi, 1987).…”

Section: Forces Bringing the Cells To The Streakmentioning

confidence: 97%

Mechanisms, mechanics and function of epithelial–mesenchymal transitions in early development

Shook

Keller

2003

Mechanisms of Development

508

428

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Epithelial-mesenchymal transitions (EMTs) are an important mechanism for reorganizing germ layers and tissues during embryonic development. They have both a morphogenic function in shaping the embryo and a patterning function in bringing about new juxtapositions of tissues, which allow further inductive patterning events to occur [Genesis 28 (2000) 23]. Whereas the mechanics of EMT in cultured cells is relatively well understood [reviewed in Biochem. Pharmacol. 60 (2000) 1091; Cell 105 (2001) 425; Bioessays 23 (2001) 912], surprisingly little is known about EMTs during embryonic development [reviewed in Acta Anat. 154 (1995) 8], and nowhere is the entire process well characterized within a single species. Embryonic (developmental) EMTs have properties that are not seen or are not obvious in culture systems or cancer cells. Developmental EMTs are part of a specific differentiative path and occur at a particular time and place. In some types of embryos, a relatively intact epithelium must be maintained while some of its cells de-epithelialize during EMT. In most cases de-epithelialization (loss of apical junctions) must occur in an orderly, patterned fashion in order that the proper morphogenesis results. Interestingly, we find that de-epithelialization is not always necessarily tightly coupled to the expression of mesenchymal phenotypes.Developmental EMTs are multi-step processes, though the interdependence and obligate order of the steps is not clear. The particulars of the process vary between tissues, species, and specific embryonic context. We will focus on 'primary' developmental EMTs, which are those occurring in the initial epiblast or embryonic epithelium. 'Secondary' developmental EMT events are those occurring in epithelial tissues that have reassembled within the embryo from mesenchymal cells. We will review and compare a number of primary EMT events from across the metazoans, and point out some of the many open questions that remain in this field.

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“…ECM fibrils radiate radially from the chick primitive streak region (England, 1981). This radial organization appears to be the result of tension (Kucera and Monnet-Tschudi, 1987).…”

Section: Forces Bringing the Cells To The Streakmentioning

confidence: 97%

Mechanisms, mechanics and function of epithelial–mesenchymal transitions in early development

Shook

Keller

2003

Mechanisms of Development

508

428

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“…Special care was taken to avoid damage to the underlying vitelline membrane. A single, straight, longitudinal, or transverse wound, approximately 0.2-0.5 mm long, was made on one side of the neural fold or tube in the midbrain region with a cactus needle (England, 1981). For stage 6 and 8 embryos in which neural folds were present, the rostra1 end of the notochord served as a guide to the midbrain region and wounds were made in the neural folds about halfway between the region of the notochord and the edge of the neural fold.…”

Section: Wound Healing Studiesmentioning

confidence: 99%

Studies on wound healing in the neuroepithelium of the chick embryo

Lawson

England

1992

Anat. Rec.

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Wound healing has been studied by light microscopy, SEM, and TEM in the neuroepithelium of the early neurula (stages 6 and 8) and advanced neurula (stages 10 and 12) chick embryos. Healing involves two major events: (1) apposition of the wound edges and (2) restitution of the neuroepithelium at the wound site (i.e., restoration of the epithelial integrity of neuroepithelium). Apposition of the wound edges occurs within the first 15 minutes of re-incubation and involves the entire length of the wound. The main event during restoration is a change in the shapes of the rounded cells to elongated forms (i.e., spindle, wedge, and inverted wedge shapes). Wounds of younger embryos heal faster than those of older ones.

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“…This region was identified ( Fig. 1) and the hypoblast overlying this border was carefully dissected away in a single piece using Rebutia hybrid cactus needles mounted on wooden cocktail sticks (England, 1981). As the hypoblast was separated up to 30-40 PGCs floated free and came to settle on the underlying ectoderm layer.…”

Section: Isolation Of Pgcs For Culturementioning

confidence: 99%

Isolation of chick primordial germ cells from stages 4–8 embryos

Matsumura

England

1993

Anat. Rec.

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Chick embryo primordial germ cells (PGCs) stages 4-8 were manually isolated for the first time from the late hypoblast layer. They were confirmed to be PGCs by periodic acid-Schiff (PAS) staining and examination by scanning electron microscopy (SEM). They were subsequently introduced onto a variety of artificial substrata. On two dimensional substrata, the cells change from a spherical shape covered with numerous microvilli to a rounded cell with a "skirt" of cytoplasm. Eventually a process projects from one side of the smooth cell. On a three dimensional substrate the PGCs change from a spherical shape covered with numerous microvilli to a smooth surfaced cell with a long single process. It is concluded that the PGCs which are originally spherical in situ in stage 4 alter their morphology both in vivo during their migration and in vitro studies.

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Applications of the SEM to the analysis of morphogenetic events

Cited by 13 publications

References 34 publications

Mechanisms, mechanics and function of epithelial–mesenchymal transitions in early development

Mechanisms, mechanics and function of epithelial–mesenchymal transitions in early development

Studies on wound healing in the neuroepithelium of the chick embryo

Isolation of chick primordial germ cells from stages 4–8 embryos

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