Cell death in metamorphosis

Lockshin, Richard A.

doi:10.1007/978-94-011-6921-9_4

Cited by 56 publications

(31 citation statements)

References 151 publications

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“…Indeed, prefunctional zooids were found to exhibit a PVEM immunostaining pattern characteristic of midcycle individuals. From this standpoint, the takeover process in BotryZEus exhibits close parallels with metamorphosis of anuran amphibians, in which a complete remodeling of body architecture takes place under the control of thyroid hormones (Lockshin, 1981). One of the first morphological alterations that occurs is the retraction of the tail fin, a process during which the extracellular matrix is degraded.…”

Section: Discussionmentioning

confidence: 99%

“…Cell death plays a fundamental role in various schemes, 0 1992 WILEY-LISS, INC. amongst which include the swift removal of larval organs in anuran amphibians (Lockshin, 1981;Yoshizato, 1989) and ascidians (Schiaffino et al, 1974) at metamorphosis, and holometabolous insects during adult emergence (Schwartz and Truman, 19841, sculpting of the nervous system (Hamburger and Oppenheim, 1982), remodeling of limbs and digits (Saunders, 1966;Hinchcliffe, 19811, and the establishment of selftolerance in the vertebrate immune system (Smith et al, 1990;Murphy et al, 1990). The elimination of transient or obsolete organs and structures is also believed to play an integral part in the morphogenetic changes leading to the acquisition of form and function (Glucksmann, 1951;Saunders, 1966).…”

Section: Introductionmentioning

confidence: 99%

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A cyclical, developmentally‐regulated death phenomenon in a colonial urochordate

Lauzon

Ishizuka

Weissman

1992

Developmental Dynamics

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Botryllus schlosseri is a colonial ascidian whose asexually derived, clonally modular systems of zooids exhibit developmental synchrony. The blastogenic cycle culminates in a phase of programmed cell and zooid death called takeover, in which all functional zooids die over a 30 hr period, and are replaced by a new generation of individuals. Because of the weekly recurrence and magnitude of visceral death in this model organism, we have begun to characterize the mechanisms that govern takeover. Here we describe a monoclonal antibody (B3F12.9) that recognizes a novel 57 Kd polypeptide (under reducing conditions) localized to the perivisceral extracellular matrix (PVEM) of buds and zooids, as well as blood cells of Botryllus by immunofluorescence and immunogold labeling of tissue sections. During their active feeding phase, zooids exhibited a uniform labeling pattern of PVEM along their anteroposterior (A-P) axis. At the onset of takeover (T = 3 hr), B3F12.9 immunostaining became diffuse or absent at the anterior end, which paralleled the axis of contraction of the dying zooid, whereas the posterior end retained its labeling integrity. During mid (T = 15 hr) to late (T = 28 hr) takeover, issue damage was extensive, large blood macrophages and other B3F12.9 immunoreactive blood cells invaded the peribranchial cavity, whereas PVEM labeling gradually disappeared along the entire A-P axis. These findings indicate that takeover is a dynamic process in which extracellular matrix breakdown proceeds in a polarized fashion, beginning at the anterior end of each zooid and gradually propagating toward the posterior end. o 1992 WiIey-Liss, Inc.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A cyclical, developmentally‐regulated death phenomenon in a colonial urochordate

Lauzon

Ishizuka

Weissman

1992

Developmental Dynamics

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“…In this remodelling process, programmed cell death (apoptosis) occurs widely in larval-specific organs (tail, gill, pronephros) but also in larva-toadult organs such as skin, intestine or liver (Lockshin, 1981 ;Yoshizato, 1989 ;Ishizuya-Oka, 1996). The term apoptosis was proposed for controlled cell deletion during development and in cell turnover in many healthy and adult tissues (Kerr et al 1972) as well as for tissue destruction in metamorphic tadpoles (Kerr et al 1974) based on morphological observations.…”

Section: mentioning

confidence: 99%

Regression of blood vessels in the ventral velum of Xenopus laevis Daudin during metamorphosis: light microscopic and transmission electron microscopic study

Bartel¹,

Lametschwandtner²

2000

Journal of Anatomy

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Structural changes of the ventral velum of Xenopus laevis tadpoles from late prometamorphosis (stage 58) to the height of metamorphic climax (stage 62) were examined by light and transmission electron microscopy. Special emphasis was given to the blood vessel regression. Early changes of velar capillaries were formation of luminal and abluminal endothelial cell processes, vacuolation, and cytoplasmic and nuclear chromatin condensation. At the height of metamorphic climax, transmission electron microscopy revealed apoptotic endothelial cells with nuclear condensation and fragmentation, intraluminal bulging of rounded endothelial cells which narrowed or even plugged the capillary, and different stages of endothelial cell detachment ('shedding') into the vessel lumen. These changes explain the 'miniaturisation' of the velar microvascular bed as well as the typical features found in resin-casts of regressing velar vessels which have been observed in a previous scanning electron microscopy study of the ventral velum.

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“…Insects provide clear examples of cell deletion as part of their normal development and metamorphosis (Lockshin, 1981). Interestingly, in insects, plants, and some other invertebrates a manifestly genetically programmed cell death with concomitant selective gene expression, new mRNA, and protein synthesis leads to a nonapoptotic form of cell death involving DNA synthesis and endoreduplication (rather than endonuclease-induced laddering).…”

Section: Introductionmentioning

confidence: 99%