ERECTILE TISSUE, (tela erectilis ; Fr. tissu erectile ; Germ. das erectile, oder schwell bare Gewebe,) a structure composed prin cipally of bloodvessels, intimately interwoven with nervous filaments. This tissue in its ordi nary state is soft, flaccid, and spongy ; but when influenced by various causes of excite ment, whether these consist of stimuli directly applied, or operating through the medium of the sensorium, it exhibits the faculty of admit ting an influx of blood much greater in quantity than what is sufficient for its nutrition, and in virtue of which it suffers a state of turgescence giving rise to a swollen condition, with more or less of rigidity and increased sensibility of the organs into the structure of which it enters, and which state has been long known by the name of erection. From the property of under going erection peculiar to this tissue, Dupuytren and Ruiner first applied to it the term ereclile, and the propriety of this distinguishing appel lation is now very generally admitted by anato mical authors.
The erectile tissue is developed in various degrees in the several parts of the animal economy in which it occurs ; it is abundant and particularly evident in the corpora caver nosa penis, corpus spongiosum urethra?, clitoris, nymph, plexus retiformis, the nipples of the mammary glands, less marked in the red borders of the lips, &c.; it also enters into the structure of the papillae of the skin and the villi of the mucous membranes which possess the property of becoming erected in the per formance of their functions, as is exemplified in the papillae of the tongue. These consist of the pulpy terminations of nerves enveloped by this tissue ; in their unexcited state they appear small, pale, soft, and shrunken ; but when excited to erection, they become increased in size, stiff, red, and distended with blood, at the same time that their sensibility is remark ably exalted. The foregoing remarks apply equally to the cutaneous papilla, articularly those on the pulpy extremities Of the fingers, where the sense of touch is developed in its highest degree of perfection.
Erectile tissue has also been recognised in the callosities on the buttocks of some of the quadrumana, in the comb and gills of the cock, the wattles of the turkey, and in the tongue of the charnel ion.* It is not improbable that this tissue enters into the structure of the iris ; and Bedard seems disposed to consider that it exists in the spleen, as well from the appearance which that organ presents when a section of it is made, as from the different states in which it is found on opening the bodies of animals; being sometimes contracted and corrugated on the surface and at other times plump, smooth, and swollen.
In some of the situations above enumerated, the erectile tissue is enclosed in a fibrous sheath which limits its extent and determines the form of the organs in which it occurs ; while in other situations it is deployed superficially, as in the tegumentary organs.
It is in the corpora cavemosa penis and corpus spoogiosum urethra, however, that the erectile tissue has been more especially made the subject of anatomical .and physiological research ; and the results of the investigations instituted in these organs have been rather inferred from analogy than directly proved as equally applicable to it in all other situations in which its existence has been indicated.
According to De Graaf, Ruysch, Duverney, Boerhaave, Haller, and Biehat, the cavernous bodies of the penis and urethra consist of a loose and elastic spongy tissue formed of in numerable cells, into which, during erection, blood is poured from the arteries, and from which it is afterwards removed by an absorbing power of the veins. Such an opinion would accord with the appearances observed by examining sections of this structure after having been inflated and dried, but careful examina tion of it when previously prepared by injec tion, proves the foregoing opinion to be founded in error.