The chalaza (/ k ə ˈ l eɪ z ə /; from Ancient Greek χάλαζα (khálaza) ' hailstone '; pl.: chalazas or chalazae / k ə ˈ l eɪ z i /) is a structure inside bird eggs and plant ovules. It attaches or suspends the yolk or nucellus within the larger structure.

Apr 1, 1997 · The chalaza is the region of the ovule where the nucellus, integuments, and funicle merge, and therefore usually encompasses a vascular bundle. The interface between chalazal and nucellar tissues is more or less on a line drawn between the ventral and dorsal limits of the inner integument, where it emerges from the chalaza (Fig. 1) (Rudall et ...

In Arabidopsis, the endosperm partially eliminates the nucellus and imports sugars from the seed coat. Here, we show that the nucellus is symplasmically connected to the chalaza, the seed nutrient unloading zone, and works as both a sugar sink and source alongside the seed coat.

Apr 20, 2023 · The main difference between micropyle and chalaza is that a micropyle is a small opening in the outer integument of an ovule, whereas a chalaza is the base of the ovule where the nucellus and the integuments join.

The chalaza is the region of the ovule where the nucellus, integuments, and fu- nicle merge, and therefore usually encompasses a vascular bundle. The interface between

May 1, 2002 · Ovules give rise to the gametophyte in the distal nucellus and form protective sporophytic organs from the underlying chalaza. We show that the WUSCHEL (WUS) homeobox gene provides a mechanism to coordinate these events.

In Arabidopsis, ovule primordia contain three functional regions: funiculus, chalaza, and nucellus (Schneitz et al., 1995). The funiculus is connected to the placenta and develops vascular tissues that supply nutrients to the rest of the ovule.

Proximal nucellar structures arise from a multi-layered region of the ovule and include hypostase, enlarged dermal cells and conducting passage (Zuleitungsbahn), haustoria, postaments, podia, and perisperm. In some cases they may represent the same tissues at different developmental stages; in general the last three are seed structures.

In Arabidopsis seeds, nucellus elimination begins 2 days after flowering (DAF) and progresses in a distal–proximal fashion to achieve the loss of 50% of its cells by 8 DAF. A few layers of proximal nucellus cells persist and expand with the rest of the ovules to form a gate between chalaza and endosperm till embryo maturity (Xu et al. 2016).

The ovule is a small structure present in the ovary. It is attached to the placenta by a stalk called a funicle. The funicle provides nourishment to the ovule. On the basis of the relative position of micropyle, body of the ovule, chalaza and funicle, there are six types of ovules.