According to ayurveda our body is formed by Tridosha (Vata,Pitta,Kapha), Saptadhatu (Rasa,rakta,mamsa,meda,asthi,majja and sukra) And Trimala (Mala,mutra and sweda). Equilibrium state of Tridosha, saptadhatu and trimala is responsible for healthy life.
The food which we take is convereted to ahar rasa by jatharagni (diagestive power). This ahar rasa is passed through blood circulation to each and every tissue (dhatu) of body for their nourishment.The nourishment of all dhatus is influenced by their respective dhatwagnis. This Dhatwagni is responsible for the motivation of self clone formation and Their Upadhatu formation.This dhatwagni also provides the necessary supplement to all dhatus and upadhatus. Thus Rasa,Rakta,Mamsa,Meda,Asthi,Majja and Sukra Dhatus develop sequentially and nourish futher dhatus. For example Rasadhatvagni plays an important role in the formation of Rakta Dhatu from Rasa Dhatu which further nourishes the Mamsa Dhatu by the influence of Raktadhatvagni.
Whenevere there is any defect in dhatwagni’s work ,it also hamper the formation of next dhatus. During this process, some metabolic wastes are formed which are known as Dhatumala.This phenomenon is carried out through out the life.Any type of Stroto dushti or obstration in microcirculation may leads to deformity of next tissue. \
In Ayurveda,formation and development of tissue is explained by some theories.They are called as Dhatu Poshan Nyaya.These theories are Khale Kapota Nyaya, Ksheera Dadhi Nyaya, Kedara Kulya Nyaya and Ek Kala Dhatu Pushti Nyaya.
Kshir Dadhi Nyaya
Kshir means milk and Dadhi means curd. These theory based on the convertion of milk in to yogurt.Like milk changes to curd, ahara rasa changes in sequence of nutrition of Dhatus.The process of covertion of ahar rasa in to dhatus id depend on Agni.The ahar rasa is converted in to Rasa dhatu,then rakta dhatu then otgher dhatu sequencaly. At first Ahar rasa completely changes to Rasa Dhatu, following this is the changing of Rasa Dhatu to Rakta Dhatu and so on. This is one of the ways of nutrition of different Dhatus.
As sunrays take many years to reach earth and still maintain its continuity by the continuous release of rays. Like wise it seems by this law, one Dhatu will completely end if it totally changes to other one. But due to the continuous flow of ingested food it does not occur.
Kedar Kuliya Nyaya
The word Kedar means small pieces of land and Kuliya means drain. Crops in the field get irrigated by proper drainage system in sequence manner. Same wise different Dhatus of the body get nutrition one by one in sequence through vessels. Ahar Rasa provide nourishment to 1st dhatu called Rasa dhatu.. Then Rakta Dhatu get nutrition from the rest part of Ahar Rasa and like wise till the end i.e. Shukra Dhatu.
During the transformation first Ahar Rasa reaches Rasa Vaha Shrotasa the Rasa Dhatu Agni processed the Ahar Rasa. During this process it is divided into three parts – Sthoola (Macroscopic), Sukshma (Microscopic & male excreatory). The Sthoola part gives nutrition to the self Dhatu i.e. Rasa.
Sukshma part Nourish its descendent Dhatu i.e. Rakta Updhatu. Stamya and Mala nourish its mala i.e. Kapha in this case. This way the process of Dhatu, Updhatu and Mala takes place.
Khala Kapota Nyaya
The word khala means pot and kapota means pegion, the bird. As the bird (pigeon) has to come to the pot of grain for its nourishment, like wise the Nyay Dhatus are directly nourished by Ahar Rasa without considering the sequence of nutrition. At times when there is shortage this law nourishes Dhatu or Updhatu in the body. So we can say there are three way of nourishment of Sharir Dhatus in the body. Which occur according to the need of the body. Analogy is that different birds come to pick up different foods at the harvest ground so the different Dhatus pick up different nourishment at the same harvest ground. The mansa Dhatu has a different requirement than shukra Dhatu for example. Rakta contains rakta/redness – iron. All Dhatus pick up own requirements. Even with specific requirements picked up, but we are still not done.