S-Cells (S細胞 Esu Saibō) are microscopic cells found in most Saiyans. The amount of S-Cells depends on the spirit of the Saiyan in question: the more gentle the spirit, the greater the amount of S-Cells; alternatively, when a Saiyan increases their battle power, it can also increase the amount of S-Cells in their body. S-Cells are essential to becoming a Super Saiyan, and when a Saiyan has gained enough they can transform by feeling intense levels of anger or sadness; alternatively (as demonstrated by Caulifla), by focusing their power into a tingling sensation in their upper-back (directly below their neck) the Saiyan in question can trigger the transformation into a Super Saiyan without the need for emotional stress. S-Cells can be passed down through genetics, making it easier for even partial Saiyans, such as Goku Jr. and Vegeta Jr., to become Super Saiyans.
- Presumably, artificial Saiyan hybrids such as Cell, Cell Jr., Mira, Fu, and Bio-Broly also possess S-Cells. If so, it can be assumed that Mira, Fu, and Bio-Broly require them for their Super Saiyan forms, though it is unknown how they function for Cell, though presumably they have some influence in the form of Cell's Super Saiyan state.
- Gentle Saiyans having more S-Cells may explain why Super Saiyans were rare for a long time in Universe 7 as the Saiyans there were violent and lived in a society that valued aggression and ruthlessness.
- This could also explain why Goten and Trunks were able to go Super Saiyan so easily, since they didn’t experience the same horrors that the other Saiyans did.
- This also explains why Vegeta had so much difficulty acquiring the form, as he originally believed a Saiyan had to be merciless to acquire it. However after Goku acquired the form, Vegeta came to believe a Saiyan must be pure hearted either pure good or pure evil. Vegeta believed his own Super Saiyan transformation was the result of him possessing a pure evil heart, however by the point he obtained it Vegeta's evil nature was starting to diminish as he started a relationship with Bulma implying his slight change of heart and intense gravity training allowed him to generate enough S-Cells required to transform.
- This also explains why Goku was able to acquire the transformation for the first time in a millennia as he is well known for being gentle hearted Saiyan not unlike his sons and his mother Gine. The gentle hearted Gohan was also able to achieve the form rather easily through intense training within the Hyperbolic Time Chamber. However having a gentle heart doesn't guarantee a Saiyan can acquire the transformation as shown by low class Saiyans Gine and Tarble, though they would have an easier time of acquiring it through intense training.
- Bardock's Super Saiyan transformation in Dragon Ball: Episode of Bardock was also likely influenced by his rejection of the evil planet conquering ways of his people and friendship with the Plants as well as the loving relationship Bardock had with his wife Gine which presumably helped him generate enough S-Cells to transform after the increase in power he received from surviving Frieza's Supernova.
- The lack of understanding the role S-Cells play in the Super Saiyan transformation has given raise to the misconception that a Saiyan must be pure hearted something that both Tien Shinhan and Vegeta assumed to be true.
- The Legendary Saiyans Broly and Kale both possess gentle hearts which presumably allows them to generate enough S-Cells to achieve their unique line of Super Saiyan forms including Legendary Super Saiyan.
- Presumably evil Saiyans like Nappa, Raditz, Turles, and Paragus have a harder time generating S-Cells. However as shown by Nappa and Cunber evil Saiyans can generate enough S-Cells to become Super Saiyans by increasing their battle power. Cunber, Nappa, and Raditz also was abie to generate enough S-Cells to achieve Super Saiyan 3.