This section is from the book "The Sushruta Samhita", by Kaviraj Kunja Lal Bhishagratna. Also available from Amazon: The Sushruta Samhita.
The male reproductive element (Sukra) is endowed with Soma-guna (i.e, thermolytic properties) the female element Artava) presents the opposite property and is therefore Agni-guna (i e., thermogenetic properties). The principles of earth, water, fire, air and ether are also present in men in their subtile forms and contribute to the formation of the material parts by their molecular adjustment in the way of supplying nutrition and in way of the adding to their bulk. 2.
The local Váyu (nerve-force) heightens or aggravates the heat generated by the friction of the sexual organs in an act of copulation. The Váyu and heat thus aggravated tend to dislodge the semen from its sac or receptacle in a man which enters into the uterus of a woman through the vaginal canal and there it mixes with the ovum (Artavam) dislodged and secreted by similar causes. The combined ovum and semen are subsequently confined in the uterus (Garbhás'aya). After that, He who is known by the epithet; of Self-conscious, impressioner (creator of sensations and perceptions), toucher, smeller, seer, hearer, taster, Self or Ego, creator, wanderer, witness, ordainer, speaker, though eternal, unmanifested and incomprehensible in his real nature, takes hold of the five subtile or essential material principles contributed by the united impregnating matter, assumes a subtile shape throughout, marked by the three fundamental qualities of Sattva, Rajas and Tamas, and led away by the Váyu, lies confined in the uterus to be subsequently evolved out in the shape of a god, animal, or monster, as determined by his acts in the former existence. 3.
The birth of a male-child marks the preponderance of semen over the ovum (in its conception); the birth of a daughter shows the preponderance of the maternal element. A child of no-sex (hermaphrodite) is the product when ovum and sperm are equal (in their quality and quantity). The first twelve nights after the cessation of the flow should be deemed as the proper period for conception, as being the time during which the ova are secreted. Certain authorities hold that there are women who never menstruate to all appearances 4 - 5.
The face of a woman (lit: a woman of undetected menstruation) becomes full and lively A moist and clumsy deposit is found on the body, face, teeth and gums. She feels a desire for sexual intercourse and speaks sweet words. Her eyes, hair, and belly droop down. A sort of distinct throbbing is felt in her arms, thighs, mammae, umbilicus, perineum and buttocks. Her sexual desire grows intense and prominent, and its gratification gives her utmost joy and pleasure. These symptoms will at once indicate that a woman has menstruated (internally). 6.
Just as the petals of a full blown lotus flower are gathered up during the night, so the uterus (Yoni) of a woman is folded up (i.e., os of the uterus is closed) after the lapse of the menstrual period (ie. fifteen days from the date of the flow). The menstrual flow, accumulated in the course of a month, is led in time by the local Váyu through its specific duct (Dhamani) into the mouth of the uterus (Yoni) whence it flows out odourless and blackish. 7.
 
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