Epididymis secretions from

Seminal vesicle secretions from many species are known to harbor a large number of enzymes, many of which may simply originate from the cytoplasm of the secretory epithelial cells and play no functional roles in seminal plasma. Comprehensive accounts of the enzyme muster of vesicular secretions are provided in several treatises (1, 4, 5, 215). Only vesicular secretion enzymes that are of potential regulatory significance will be considered here. It is noteworthy that many highly active enzymes in seminal plasma originate from the epididymis and(or) the prostate gland (4, 5). 

Okamura, N., M. Tamba, H. J. Liao, S. Onoe, Y. Sugita, F. Dacheux, and J. L. Dacheux, Cloning of complementary DNA encoding a 135-kilodalton protein secreted from porcine corpus epididymis and its identihcation as an epididymis- specific a-mannosidase. Mol Reprod. Dev., 1995,42, 141-148. 

OTR is also expressed in male reproductive tissues, like testis, epididymis and in the prostate. OT increases the resting tone of prostatic tissue from guinea pig, rat, dog and human. The activation of these receptors could lead to the contraction of the prostate and the resulting expulsion of prostatic secretions during ejaculation. 

Figure 19.1 A diagrammatic representation of the male reproductive tract. Much of the volume of the testes consists of convoluted seminiferous tubules in which the spermatozoa form. In the interstitial tissue that surrounds the seminiferous tubules are the Leydig cells which produce and secrete androgens, oes-tradiol and the peptides inhibin and activin. The epididymis is a single but convoluted tube. Sperm from the epididymis enter the vas deferens and pass through the ejaculatory duct into the urethra, mainly at the time of ejaculation. Just at the transition of the vas deferens to ejaculatory duct, two large glands, the seminal vesicles, drain into the two vasa deferentia. Prior to joining the urethra, the ejaculatory ducts pass through the prostate gland which lies below the bladder and surrounds the upper part of the urethra, into which prostatic fluid is secreted.

During development, a portion of the mesonephric kidney develops into two different ducts, the Wolffian and Mullerian ducts. The Wolffian duct, under the influence of testosterone, differentiates into the vas deferens, the epididymis, and the seminal vesicle. A second pair of embryonic ducts, the Mullerian ducts, develops alongside the Wolffian ducts. In males, the Mullerian ducts are suppressed due to the action of Miillerian-inhibiting substance (MIS), a hormone secreted by the testes. Maleness depends upon the secretion of testosterone from the testis, and in the absence of testosterone a male will develop a female phenotype. The SRY gene apparently activates the synthesis of MIS, which in turn assures that the Mullerian ducts will atrophy and that the mammal develops as a male. 

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