Table 1 Summary of the histological observations in the different flowers and ovules from Sangiovese cv. examined at three phenological stages

E-L 15

Longitudinal

Beginning stages of ovule development

Initiation of inner integument

Signs of initiation of periclinal divisions of cells at the base of the inner integument

Nucellus is developing, consists of 2–3 layers of cells

Archaeospore, mitosis of archaeospore

Archaeospore is in the central part of the nucellus, in some ovules mitosis of archaeospore is observed

E-L 17

Longitudinal

All ovules are anatropous

Developed inner integument, three layers of cells

Developed outer integument. Four to seven layers of cells in different parts of the ovule

Normally developed

Surviving megaspore after meiosis of MMC. In some ovules megagametogenesis during the first or second mitosis

There is a small space for processes of megasporogenesis in the centre of nucellus

E-L 17

Transversal

Ovaries mainly constituted by two locules and four ovules, rarely by three locules and six ovules

Developed inner integument, three layers of cells

Developed outer integument. Four to seven layers of cells in different parts of the ovule

Normally developed

Megaspores

In some ovules there is a narrow space between the inner and the outer integument

E-L 26

Longitudinal

Developed ovules with cells of embryo sac or degenerating ovules without embryo sac elements

Developed inner integument, three layers of cells

Developed outer integument. Four to seven layers of cells

Normally developed

Mature embryo sac with central cell, synergids and egg cell

In some ovules there is a space between the inner and outer integuments, sometimes between inner integument and the nucellus even in ovules with cells of embryo sac. Exfoliated integuments are the first sign of ovule degeneration

E-L 26

Transversal

Ovaries mainly constituted by two locules and four ovules, rarely by three locules and six ovules. Elements of fertilization process undertaking

Developed inner integument, three layers of cells

Developed outer integument. Four to seven layers of cells

Normally developed

Cells of the embryo sac separately in different sections: central cell or synergids and egg cell. Evidences of fertilization process: zygote, endosperm, sperm cell

There is a space between the inner and outer integuments in the majority of ovules. In some slides a small space between integuments and/or nucellus could be due to microtome damaging because microtome tearing was also observed in these slides