Table 2.
Evidence for the existence of releasing factors.
| T = the theory that releasing factors come from the hypothalamus to the anterior pituitary (Harris) | |||
|---|---|---|---|
| ~T = the theory of vasopressin or oxytocin controlling the release of hormones from the pituitary (McCann) | |||
| E1 = direction of blood flow thru portal vessels is from the hypothalamus to the pituitary | |||
| E2 = cutting portal vessels stops hormone secretion by the pituitary (Harris) | |||
| E3 = vasopressin can stimulate ACTH release (McCann) | |||
| E4 = hypothalamic fragments introduced to pituitary cell cultures release ACTH (Guillemin and Schally) | |||
| E5 = nerve fibers connecting the hypothalamus to the posterior pituitary contain vasopressin | |||
| Probability | Value | Code | Description |
| P(T)= | 0.5 | Hypothalamus secretes factors that stimulate the pituitary to secrete various hormones | |
| P(~T)= | 0.5 | 1 – P(T) vasopressin or oxytocin in the posterior pituitary control the release of hormones by the pituitary | |
| P(E1|T)= | 0.6 | WC | Blood vessels connecting the hypothalamus to the pituitary is weakly consistent with transmission of releasing factors |
| P(E1|~T)= | 0.5 | N | Blood vessels going to the anterior pituitary is neutral to the source of vasopressin from the posterior pituitary |
| P(E2|T)= | 0.7 | SC | Cutting portal vessels is strongly consistent with blocking the releasing factors from entering the anterior posterior |
| P(E2|~T)= | 0.4 | WI | Cutting the vessels to stop ACTH is weakly inconsistent with vasopressin controlling ACTH from the posterior pituitary |
| P(E3|T)= | 0.3 | SI | Vasopressin stimulation of ACTH is strongly inconsistent with a factor from the hypothalamus |
| P(E3|~T)= | 0.7 | SC | Vasopressin control of the pituitary is strongly consistent with ACTH release |
| P(E4|T)= | 0.7 | SC | Hypothalamus tissue in a pituitary cell culture producing ACTH is strongly consistent with hypothalamic origin of factors |
| P(E4|~T)= | 0.3 | SI | Cell culture release of ACTH is strongly inconsistent with vasopressin control of ACTH |
| P(E5|T)= | 0.5 | N | Nerve fibers to the posterior pituitary are neutral regarding the hypothalamic origin of releasing factors |
| P(E5|~T)= | 0.6 | WC | Nerves containing vasopressin connecting to the pituitary is weakly consistent with control of ACTH release |
| P(T|E1-E5)= | 0.64 | Confirm | |
T stands for the theory or model under consideration and ~T (not T) the alternative theory or theories. Lines of evidence are numbered E1 through E5. A brief statement of each theory and line of evidence is given at the top of the table. In the body of the table prior and posterior probabilities are shaded in yellow. Conditional probabilities are shaded green for the theory being tested and pink for the alternative. The column headed Description is a short explanation of the consistency or inconsistency of the theory and evidence, while the Code and Value columns give probabilities from Table 1. The last line in the table gives the posterior probability according to Bayes' rule which confirms if it is greater than the prior. Bolded words in the Description column indicate the relationship between the theory and evidence in accord with the abbreviations in the Code column.