Objection 1. It would seem that whatever was materially in a man's members will all rise again. For the hair, seemingly, is less concerned in the resurrection than the other members. Yet whatever was in the hair will all rise again, if not in the hair, at least in other parts of the body, as Augustine says (De Civ. Dei xxii) quoted in the text (Sent. iv, D, 44). Much more therefore whatever was materially in the other members will all rise again.
Objection 2. Further, just as the parts of the flesh are perfected as to species by the rational soul, so are the parts as to matter. But the human body is directed to the resurrection through being perfected by a rational soul. Therefore not only the parts of species but also the parts of matter will all rise again.
Objection 3. Further, the body derives its totality from the same cause as it derives its divisibility into parts. But division into parts belongs to a body in respect of matter the disposition of which is quantity in respect of which it is divided. Therefore totality is ascribed to the body in respect of its parts of matter. If then all the parts of matter rise not again, neither will the whole body rise again: which is inadmissible.
On the contrary, The parts of matter are not permanent in the body but ebb and flow, as stated in De Gener. i. If, therefore, all the parts of matter, which remain not but ebb and flow, rise again, either the body of one who rises again will be very dense, or it will be immoderate in quantity.
Further, whatever belongs to the truth of human nature in one man can all be a part of matter in another man, if the latter were to partake of his flesh. Therefore if all the parts of matter in one man were to rise again it follows that in one man there will rise again that which belongs to the truth of human nature in another: which is absurd.
I answer that, What is in man materially, is not directed to the resurrection, except in so far as it belongs to the truth of human nature; because it is in this respect that it bears a relation to the human souls. Now all that is in man materially belongs indeed to the truth of human nature in so far as it has something of the species, but not all, if we consider the totality of matter; because all the matter that was in a man from the beginning of his life to the end would surpass the quantity due to his species, as the third opinion states, which opinion seems to me more probable than the others. Wherefore the whole of what is in man will rise again, if we speak of the totality of the species which is dependent on quantity, shape, position and order of parts, but the whole will not rise again if we speak of the totality of matter. The second and first opinions, however, do not make this distinction, but distinguish between parts both of which have the species and matter. But these two opinions agree in that they both state what is produced from the seed will all rise again even if we speak of totality of matter: while they differ in this that the first opinion maintains that nothing will rise again of that which was engendered from food, whereas the second holds that something but not all, thereof will rise again, as stated above (Article 4).
Reply to Objection 1. Just as all that is in the other parts of the body will rise again, if we speak of the totality of the species, but not if we speak of material totality, so is it with the hair. In the other parts something accrues from nourishment which causes growth, and this is reckoned as another part, if we speak of totality of species, since it occupies another place and position in the body, and is under other parts of dimension: and there accrues something which does not cause growth, but serves to make up for waste by nourishing. and this is not reckoned as another part of the whole considered in relation to the species, since it does not occupy another place or position in the body than that which was occupied by the part that has passed away: although it may be reckoned another part if we consider the totality of matter. The same applies to the hair. Augustine, however, is speaking of the cutting of hair that was a part causing growth of the body; wherefore it must needs rise again, not however as regards the quantity of hair, lest it should be immoderate, but it will rise again in other parts as deemed expedient by Divine providence. Or else he refers to the case when something will be lacking to the other parts, for then it will be possible for this to be supplied from the surplus of hair.
Reply to Objection 2. According to the third opinion parts of species are the same as parts of matter: for the Philosopher does not make this distinction (De Gener. i) in order to distinguish different parts, but in order to show that the same parts may be considered both in respect of species, as to what belongs to the form and species in them, and in respect of matter, as to that which is under the form and species. Now it is clear that the matter of the flesh has no relation to the rational soul except in so far as it is under such a form, and consequently by reason thereof it is directed to the resurrection. But the first and second opinions which draw a distinction between parts of species and parts of matter say that although the rational soul perfects both parts, it does not perfect parts of matter except by means of the parts of species, wherefore they are not equally directed to the resurrection.
Reply to Objection 3. In the matter of things subject to generation and corruption it is necessary to presuppose indefinite dimensions before the reception of the substantial form. Consequently division which is made according to these dimensions belongs properly to matter. But complete and definite quantity comes to matter after the substantial form; wherefore division that is made in reference to definite quantity regards the species especially when definite position of parts belongs to the essence of the species, as in the human body.
Source: Summa Theologica (New Advent)