The Compendium of Caraka 4.7.4

4.7.4

tamuvāca bhagavānātreyaḥ --- śṛṇu matto 'agniveśa ! sarvaśarīramācakṣāṇasya yathāpraśnamekamanā yathāvat / śarīre ṣaṭ tvacaḥ ;tadyathā --- udakadharā tvagbāhyā, dvitīyā tvasṛgdharā,tṛtīyā sidhmakilāsasaṃbhavādhiṣṭhānā,catuethī dadrūkuṣṭhasaṃbhavādhiṣṭhānā,pañcamī tvalajīvidradhisaṃbhavādhiṣṭhānā,ṣaṣṭhī tu yasyāṃ chinnāyāṃ tāmyatyandha iva ca tamaḥ praviśati yāṃ cāpyadhiṣṭhāyārūṃṣi jāyante parvasu kṛṣṇāraktāni sthūlamūlāni duścikitsyatamāni ca ; iti ṣaṭ tvacaḥ / etāḥ ṣaḍaṅgaṃ śarīramavatatya tiṣṭhanti //

The venerable Ātreya said to him: “Listen attentively and accurately to me, Agniveśa, as I explain the entire body according to your question. In the body there are six layers of skin; namely: the outermost skin is the water-bearing; the second is the blood-bearing; the third is the seat of the origin of sidhma and kilāsa; the fourth is the seat of the origin of dadru and kuṣṭha; the fifth is the seat of the origin of alajī and vidradhi; and the sixth is that which, when cut, makes one swoon and enter darkness as if blind, and resting upon which boils arise on the joints—dark reddish, thick-rooted, and most difficult to cure; these are the six layers of skin. These remain covering the six-limbed body.