There seems to be more than ten
Manasa Putra of Lord Brahma as I have described in this answer. Some
Puranas include Svayambhuva Manu and Shatarupa also in the list of Lord Brahma's mind-born children.
According to Vishnu Purana and Shrimada Bhagavatam, Lord Brahma divided himself into two parts. Male part is Svayambhuva Manu and female part is Shatarupa.
Then Brahmā created himself the Manu Svāyambhuva, born of, and identical with, his original self, for the protection of created beings; and the female portion of himself he constituted Śatarūpā, whom austerity purified from the sin (of forbidden nuptials), and whom the divine Manu Svāyambhuva took to wife. Vishnu Purana, Book 1, Chapter 7
Shrimada Bhagavatam, Chapter 3.12 also describes the same story.
aho adbhutam etan me
na hy edhante prajā nūnaṁ
daivam atra vighātakam (3.12.51)
Brahmā thought to himself: Alas, it is wonderful that in spite of my being scattered all over, there is still insufficient population throughout the universe. There is no other cause for this misfortune but destiny.
evaṁ yukta-kṛtas tasya
daivaṁ cāvekṣatas tadā
kasya rūpam abhūd dvedhā
yat kāyam abhicakṣate (3.12.52)
While he was thus absorbed in contemplation and was observing the supernatural power, two other forms were generated from his body. They are still celebrated as the body of Brahmā.
mithunaṁ samapadyata (3.12.53)
The two newly separated bodies united together in a sexual relationship.
yas tu tatra pumān so ’bhūn
manuḥ svāyambhuvaḥ svarāṭ
strī yāsīc chatarūpākhyā
mahiṣy asya mahātmanaḥ (3.12.54)
Out of them, the one who had the male form became known as the Manu named Svāyambhuva, and the woman became known as Śatarūpā, the queen of the great soul Manu.
So, from above two sources it is clear that Svayambhuva Manu sprang from Lord Brahma's body.