The nucleus occupies about 10% of the cell. It can move from cell to cell, also moving within a cytoplasm, but does not have a fixed position.
Most cells only presents a nucleus, but several can exist. Often, there are two nucleus, usually of different size,
a macro one with a metabolic function,
and a micro nucleus, with a reproductive function.
Usually the nucleus has round shape and its appearance varies with the age of the cell and its life cycle.

It consists of:
-a nuclear membrane also called nuclear envelope,
-a nucleoplasm, which is an aqueous solution of molecules (ions, enzymes, nucleotides, etc.),
-the chromatin (color) unveils its high affinity for basic pigments.
-the nucleolin (usually a nucleolus per cell), that are visible structures inside the nucleus, more or less spherical, until cell division.

The seeds have a structure similar to the ovum because it`s composed by two essential parts, the first integrating the second, that are:
the episperm (from the Greek epi, on)
and the almond.
The other parties may be different.
The episperm is the seed wrapper (which was the one of the ovum), of highly variable constitution, often consisting of an outer coat of tegument, called forehead, usually lasts, and an inner one, called endopleura.

This wrap will form by stages during its development, and to each level is assigned a name: primina, secundina.
In principle, the film is smooth and resister, but skins can appear in some places, particular points, edges or on the entire surface (cotton).
It is composed of two superposed membranes, the external called forehead and the internal one called internal membrane, the two becoming to glue bit-by-bit.

The almond, in the most sophisticated seeds, consists of endosperm (cell body evolved from embryonic bag), the perisperm or span class='txtorange'>albumen and the nucleus.
Other seeds will present different characteristics with the embryonic bag and their embryo (forming as a fleshy bag).

Most flowers have flowers with seeds.
If not, some few things have happened to stop the regular development of the seed formation process of the flower and the ova.
The human being is the one who wants fruits seedless, because of the needs of society consumption, and also because of agriculture, always increasing researches of species improvements, as they say, nevertheless we know that often, it is to start new markets.
But here, is not the subject.

Plants that will produce fruit without pollination are less numerous (banana, orange, tangerine, ...).
The event that was at the origin of this particularity is called parthenocarpy. The fruit wall (ovary wall or pericarp) is the delimitation of the fruit with the seed. The fruit has three separate parts that can be set, which are the exocarp or epicarp (internal wall of fruit), the mesocarp (the edible part) and the endocarp (part of the fruit dressing up the fruit cavity).
The comparison of the fruit can be made from the consistency of the pericarp on fleshy or dry.

Fruits can be divided into three categories:

*A - single-category : fruit consisting of a single ovary of a flower, which can be dry or fleshy, unicarpelmulti-carpel, but in this case with the syncarpic at maturity.
In this case, there are:

-dehiscent dried fruits (opening spontaneously to release the seeds),
as the follicles derived from a single pistil, as legumes (beans),
or as the capsule (various forms: poricidal, septicidal, loculicidal) derived from syncarpic ovary with two to many fused carpels, and finally the silique (characteristic fruit derived from the bi-carpel ovary)..

-indehiscent dried fruits (not opening spontaneously to release the seeds),
as Samara (fruit with pericarp wall expansions in wing form),
as the caryopsis or grain with a single seed (joined to the walls of the fruit, in its fullest extension),
or as achene (seed joins to the wall of the fruit by a single point).

-fleshy fruits
as the berry (epicarp thin, in general, e.g. grape), as the hesperidium (coriaceous epicarp and membranous endocarp, also divided into sections: ex. orange),
as the pepo (outer coat (epicarp) from coriaceous up to woody, fleshy pericarp, seeds soaked in succulent pulp).
as the drupe (thin epicarp, slender mesocarp, fleshy and woody endocarp, and the seed called lump because it`s strongly adhered, ex: olive.

*B - category aggregate, with fruticulus united directly by their walls, or by the drupe`s walls or indirectly, by receptacle tissue, ex raspberry.
Each pistil forms a separate fruit, usually of follicle type (apocarpous fruit).

*C - category multiple as pineapple (amount of parthenocarpy berries, plus the juicy bracts, and the axis of the inflorescence.
The fruit is called sorosis.