There is a practice in yoga in which jñānendriyas are overlapped with the fingers of both hands, it is called yoni-mudrā. A yogi enters into pratyāhāra and immerses into himself through this practice. The term ‘yoni‘ comes from the root yu, which may indicate several qualities. The first one from the adādiḥ class, means miśraṇa (join together), and the second from the kryādiḥ class, meaning bandhana (binding). That is something that connects male and female fluids, that holds and carries the fetus. The term ‘mudrā‘ also has a similar meaning, from the root mud, which happens in two classes: the first is curādiḥ class, meaning saṃsarga (mixing, combining) and the second is the bhvādiḥ class, meaning harṣa (rejoicing). This is what connects the two polarities: consciousness (meaning) and the object that displays it, as well as something that gives joy. Thus, any practice that connects you with the essence and brings joy can be considered as mudrā, it can be a mantra, a dhyāna, even āsana and prāṇāyāma, being directed to your essential predestination.
In India there is such a famous place of the Goddess as Kāmākhyā-pīṭha, where the Goddess is revered in the form of a female genital organ (yoni). All her images in the form of ten Mahāvidiyās, including the central place – the Kāmākhyā temple, have sanctuaries that are on the surface of the earth and below them, in the form of caves, that are underground. Underground is the bosom of the Mother Goddess, the bosom is considered as the essence of any Goddess, in many yantras she is presented in the form of a bindu and a triangle in the center. If you go into the main temple of Kāmākhyā, going down the stairs, you will plunge into the darkness with only the dim light of the lamps. Merging into the darkness, you are going through the experience of death, as if leaving the sanctuary, you are kind of returning to life, already updated. All the essential elements of these tantric symbols, in the form of veneration of yoni (yoni-pūjā) are also reflected in yoga practice. You are immersed in yourself during that practice, you recognise the nature of the Mother Goddess in your body in the form of Kuṇḍalinī-śakti. Also, being renewed, you will know the true self as ātman. The Mātṛkābheda-tantra says “janmasthānaṃ mahāyantraṃ” that the female reproductive organ is the Great Yantra, although the term janmasthāna can also be associated with the phallic symbol. In fact, yoni and liṅgam both are a manifestation of the bindu, also of one triangle, but only they change to male or female symbols when turned over. This is what the Bhagavad Gītā says about yoni:
सर्वयोनिषु कौन्तेय मूर्तयः सम्भवन्ति याः।
तासां ब्रह्म महद्योनिरहं बीजप्रदः पिता ।।14.4।।
sarvayoniṣu kaunteya mūrtayaḥ sambhavanti yāḥ।
tāsāṃ brahma mahadyonirahaṃ bījapradaḥ pitā ।।14.4।।
O Kaunteya, in whatever (yāḥ) yoni (sarvayoniṣu) entities (mūrtayaḥ) do not appear (sambhavanti), the yoni for them is the Great Brahman (tāsāṃ brahma mahat yoniḥ), while I am the Father (pitā) giving (pradaḥ) seed (bīja).
This śloka from the Gītā identifies the yoni with the Supreme Brahman. From the foregoing, it can be summarised that yogic mudra is a tantric symbol, it gives knowledge of birth and death (frees from rebirth, i.e. grants mukti), leads to the merging of the soul with the God (Brahman).