Lithium Chloride and Trypan Blue Induce Abnormal Morphogenesis by Suppressing Cell Population Growth

Abstract

Full primitive streak stage chick embryos were cultured in vitro for 20 hrs and monitored every 4 hr for morphology, cell number and blastoderm area. In normal embryos, the cell population growth is exponential and correlates directly with increasing morphological rank. The chick blastoderm area expands in two waves, one immediately after gastrulation and another after 16 hr in culture, while cell population growth is predominant between 4-16 hr. Trypan blue and LiCl inhibit cell population growth, epiboly and shaping of organ primordia. Both teratogens induce a similar spectrum of abnormalities although the severity of abnormal development is greater with LiCl for the given dose. In most abnormal embryos the cell population size and blastoderm area are inhibited most, which is detectable already after 12 hr of culture. We have established that the cell population growth, morphogenesis and area expansion constitute a parametric hierarchy with the cell population growth as the most independent parameter in regulating normal morphogenesis.

Post‐nodal mesoblast caudalizes the host axis and inhibits cell population growth, and induces new primitive streaks in chick embryos

“…Yamada (1994, 1995) has hypothesized that the antero–posterior specification in the mesoderm and the ectoderm is a combined effect of a positive cell cycle control during dorsalization and a positive cell cycle regulation during caudalization. Thus, caudalization is indeed regulated by a negative cell cycle control (Ghatpande et al 1991, 1993; Modak et al 1993; Joshi 1999; present data). In contrast, examination of the chronology of neural induction (Joshi 1999; Deshmukh et al 2001; Joshi‐Banka et al 2001; Chatterjee et al unpubl.…”

“…The PN region of the full primitive streak contains presumptive postero‐lateral mesoblast (Rawles 1936; Rudnick 1948; Spratt 1952; Aberchrombie & Bellairs 1954; Nicolet 1970, 1971; Khan & Mulherkar 1974, 1978). In this study, we showed that increasing the number of PN grafts transplanted in the anterior half of the area pellucida inhibited cell population growth and development of the anterior axial structures, and promoted caudalization of the host axis similar to the effects of LiCl, Trypan blue and RA (Ghatpande et al 1991, 1993; Modak et al 1993). Furthermore, the head was either of reduced size or absent, and the forebrain and midbrain, but not the tail region, were truncated.…”

“…The lengths of the host axes (anterior extremity of the telencephalon to the anterior end of the regressing streak), the head regions (from the anterior tip of the telencephalon and the posterior extremity of the rhombencephalon) and the remaining tail portions were measured in control and experimental embryos, with a micrometer. Outlines of the area pellucida, opaca and vasculosa were recorded and the surface areas (mm 2 ) at the beginning and end of culture were determined by planimetry (Ghatpande et al 1991, 1993). Host ectoblast reaction to the graft was examined both ventrally and dorsally as previously described (Guttikar et al 1993).…”

“…During early morphogenesis of the chick, the cell population growth controls blastoderm expansion (Ghatpande et al 1993; Sonawane 2000). Lithium chloride (LiCl), Trypan blue, isonicotinic acid hydrazide and retinoic acid (RA) affect both processes adversely by caudalizing the host axis, although these reagents target different biochemical processes (Nicolet 1965; Joshi et al 1990; Ghatpande et al 1991, 1993; Modak et al 1993). Therefore, caudalization has been suggested to be under a negative cell cycle control (Ghatpande et al 1991, 1993; Modak et al 1993; Yamada 1994, 1995).…”

Inhibition of heart formation by lithium is an indirect result of the disruption of tissue organization within the embryo

“…In medicine, lithium is commonly used for the treatment of bipolar disorder (Williams & Harwood 2000;Quiroz et al 2004). At high doses, lithium becomes teratogenic (Smithberg & Dixit 1982;Ghatpande et al 1993). This latter property has proven advantageous for the study of embryonic development, as lithium has provided a useful tool for uncovering cellular and molecular mechanisms of early vertebrate pattern formation (Moon & Kimelman 1998;Heasman 2006).…”