Reproductive tract, male

In order to discuss the biological mechanisms involved in the aetiology of genital tract malformations, testicular cancer and lowered sperm counts, some knowledge of the processes involved in the differentiation and development of the male reproductive tract and determination of normal testicular function is required. An early embryo has the potential to develop either a male or a female... 

Sites of Oestrogen Action and Production in the Male Reproductive Tract... 

The POMC protein is processed differendy in the anterior lobe than in the intermediate lobe. The intermediate lobe of the pituitary is mdimentary in adult humans, but it is active in human fetuses and in pregnant women during late gestation and is also active in many animal species. Processing of the POMC protein in the peripheral tissues (gut, placenta, male reproductive tract) resem-... 

SHARPE R M and SKAKKEBAEK N E (1993) Are oestrogens involved in falling sperm counts and disorders of the male reproductive tract Lancet. 341 (8857) 1392-5. 

Sampson, N, G Untergasser, E Plas, and P Berger. 2007. The ageing male reproductive tract. J Pathol 211 206-218. 

Normal pre- and postnatal male reproductive tract development. Progressive atrophy with age of rete testis and seminal tubules. Diminution of fertilizing capacity of sperm. Females Neuroendocrine system apparently normal, except for an excess of transcription of gonadotropin genes. 

Chlordecone is well distributed throughout the male reproductive tract of rats and appears in the ejaculate. In rats given a single oral dose of 40 mg/kg chlordecone, the descending order of... 

Bulger WH, Kupfer D. 1985. Estrogenic activity of pesticides and other xenobiotics on the uterus and male reproductive tract. In Thomas JA, Korach J, McLachlan JA, eds. Target organ toxicology series Endocrine toxicology. New York, NY Raven Press, 1-34. 

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.

Box 3.2 shows the toxicity package t)q)ically generated before a Phase I trial. These trials are usually conducted in males, and thus do not require formal reproductive toxicity studies. In the United States, women can be included in early trials without any animal reproductive toxicity if special precautions are taken to ensure that pregnancy does not occur. A histopathological assessment of the effects of the test compound on the male reproductive tract is made in the repeat-dose toxicity tests. 

Androgens produce both virilizing and protein anabolic actions (Table 63.1). The virilizing actions of testosterone include irreversible effects that occur during em-bryogenesis, that is, those that induce differentiation of the central nervous system and male reproductive tracts, and the excitatory actions at puberty that are... 

T. Mann, The Biochemistry of Semen and of the Male Reproductive Tract, Methuen, London, 1964. 

Differentiation and growth of the male reproductive tract, stimulation of male secondary sex characteristics, sceletal muscle growth... 

In most mammals, spermatozoa become motile while in the proximal cauda epididymis. The epididymis is also a reservoir for sperm. In addition, maturation of the spermatic plasma membrane in the epididymis involves physical and chemical alterations in the membrane lipids. Seminal and prostatic fluids are added to the semen during its passage through the male reproductive tract. 

C. myrodora. PAs transferred from the male to the female queen butterfly find their way into the eggs in substantial quantities (Dussourd et al, 1989). This transfer is not an isolated example. Studies by Brown (1984) indicated the presence of PAs in the male reproductive tract of several ithomiine species, and Boppre (1984b) has documented a diversity of breakaway particles in several danaines. The intimate relationships between the insects, their PAs, courtship behavior, and defense are clearly the result of convergence on an effective method of antipredatory defense (Wink and von Nickisch-Rosenegk, 1997). 

D. J. Hunter and R. T. Relsey, Pesticide Residues and Breast Cancer The Harvest of a Silent Spring, J. Natl. Cancer Inst. 85 (1995) 598-99 R. El-Bayoumy, Environmental Carcinogens That May be Involved in Human Breast Cancer Etiology, Chem. Res. Toxicol. 5 (1995) 585-90 R. M. Sharpe and N. F. Skakkebaek, Are Oestrogens Involved in Falling Sperm Counts and Disorders of the Male Reproductive Tract Lancet541 (1995) 1592-95. 

The hypothesis that environmental endocrine disruptors may contribute to diseases of the male reproductive tract has spurred considerable research on this area, with a particular emphasis on changes that have occurred over time. There are no apparent global changes in sperm counts and fertility, rates of hypospadias and cryptorchidism, and birth sex ratios. Testicular cancer is increasing in most countries, but it is not correlated with other indicators of male reproductive capacity. Moreover, testicular cancer is increasing while DDE and other POPs are decreasing, suggesting that exposure to these compounds is not linked to testicular cancer. 

Hess, R. A. 2000. Oestrogen in fluid transport in efferent ducts of the male reproductive tract. Rev. Reprod. 5 84—92. 

Parr, M.B., and E.L. Parr. 1994. Mucosal immunity in the female and male reproductive tracts. In Handbook of mucosal immunology, eds. P.L. Ogra, W. Strober, J. Mestecky, J.R. McGhee, M.E. Lamm, and J. Bienenstock, 667. San Diego Academic Press. 

ANDROGENIC EFFECTS Adrug s effects on the growth of the male reproductive tract and the development of male secondary sexual characteristics. 

Dithiocarbamates affected the male reproductive tracts in rats, decreased sperm motility and viability and caused testicular atrophy. Zineb acted as a sterilant in rats. 

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