The first member of a tat-puruṣa samāsa preserves its original accent when the second member is the word sadṛśa or pratirūpa expressing resemblance with someone or something.,
Thus पितृ꣡सदृशः, मातृ꣡सदृशः ॥ The words पितृ and मातृ are formed by Unadi affix तृच् (Unadi II. 95) and are finally accented. By 2.1.31, सदृश forms Instrumental Tatpurusha. That case, however, is governed by 6.2.2, which provides for Instrumental compounds. The examples here given are of Genitive Tatpurusha: and it applies to cases where the case-ending is not elided. As दास्याः꣡ सदृशो, वृषल्या꣡ सदृशः ॥ Here दासी and वृषली are finally acute, and the case-affix gets the accent when semivowel is substituted 6.1.174. So also पितृ꣡प्रतिरूपः, मातृ꣡प्रतिरूपः ॥ Why do we say 'when meaning resemblance'? Observe परमसदृशः꣡, उत्तमसदृशः꣡ (VI. I. 223): here the sense of the compound is that of 'honor' and not 'resemblance'.,