Gonad

Reproductive organs are the primary source of the steroid hormones that influence sexual and reproductive functions. In men, the testes produce testosterone and similar androgens that are responsible for spermatogenesis and the secondary sexual characteristics of adult males.7,26 In women, sexual maturation and reproductive function are governed by the production of estrogens and progestins from the ovaries.27 The release of male and female sex steroids is controlled by hormones from the hypothalamus and anterior pituitary.32 The control of male and female hormone activity and the pharmacologic implications of these hormones are discussed in Chapter 30. 

Gonadal development and the hormones of the reproductive system are discussed in section 3.6.3. 

Reproductive toxicology may be defined as any adverse effect on any aspect of male or female sexual structure or function, including conception and lactation, which may interfere with the production and development of normal offspring to maturity (Witorsch 1995). It is important to recognize the importance of reproductive and teratology studies in the detection of toxicants to the reproductive system (ICH 2005) and perhaps how little used are the biochemical measurements of the hormones that drive the reproductive systems in these regulatory studies. 

The discussion is subdivided into parts, one dealing with changes in the ovary and the other with changes in the testicle in the former, women 

Similar lesions have been described by Stefko (1928) in undernourished patients and by Mason (1939) in animals fed experimental diets. The mechanism of production of these changes probably depends on the altered hormone equilibrium to be discussed. 

The same tests were applied to 29 women of menstrual age, 4 with persisting menstruation and 25 with amenorrhea. 

As can be seen in Table I, the 4 women with persisting menstruation had normal or lowered estrogenic activity, coinciding with a generally low grade of undernourishment, and severe liver damage. 

Out of 25 women with amenorrhea, 22 showed lowered estrogenic activity with primary ovarian lesions in two cases. It is interesting to point out that, of the remaining 20, 19 had advanced stages of malnutrition. 

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This method is by far the easiest of the two methods I descnbe, but because it uses bromine liquid as a precursor to the dibromodioxane crystals a fume cupboard (or a fucking good method of fume extraction) is absolutely essential. Surgically removing ones gonads with a blunt knife would be a much less painful way of harming yourself than messing with this stuff in the kitchen. 

Two protein hormones, inhibin and activin, have been identified in gonadal tissue. Inhibin has been isolated from ovarian foUicular fluid and found to inhibit pituitary secretion of FSH. Inhibin is a glyocoprotein heterodimer consisting of two disulfide-linked subunits, a and P two types of P-subunit,... 

P and Pg, exist in foUicular fluid. Control of inhibin secretion involves a feedback relationship in which circulating FSH stimulates inhibin secretion, which in turn reduces the secretion of FSH (8). Both the homo- and the heterodimers of the P-subunits of inhibin promote the secretion of FSH and thus have been termed activins. Activin is secreted by the ovary and the testes into the circulation. In addition, both inhibin and activin have intragonadal autocrine and paracrine effects that influence gonadal steroidogenesis (9). 

The adrenal cortex produces steroidal hormones that are associated with carbohydrate, fat, and protein metabolism, electrolyte balance, and gonadal functions (58). One of these, cortisone [53-06-5] ( ) demonstrated a remarkable ability to relieve the symptoms of inflammatory conditions... 

The conversion of cholesterol (2) to pregnenolone [145-13-1] (78) is accomplished primarily through enzymatic systems in the adrenocortical and gonadal mitochondria. This conversion appears to be rate-limiting and therefore is regarded as the control point for the entire steroid hormone... 

Inhibin and Activin. Inhibin, a water-soluble, gonadal factor known for over 50 years to inhibit pituitary function, has been isolated and identified (127—130). Inhibin is a glycoprotein hormone that preferentially inhibits the secretion of FSH. It consists of an a-chain subunit, mol wt 14,000, linked by disulfide bonds to a P-chain subunit, mol wt 18,000. There exist two forms of the P-chain subunit, P-A and P-B. The smaller subunit combines with either the P-A or P-B subunit to form inhibin-A or inhibin-B, respectively. 

Fish gonadal recrudescence assay effects on light and temperature sensitive sexual maturation. 

Measurement of contaminants in fish has concentrated on muscle tissue since the aim has generally been to protect the health of the consumer rather than that of the fish. Endocrine tissue such as the gonads has been much more rarely examined, while data for adrenal, thyroid and pituitary levels are virtually non-existent. More data are available for the liver, as a lipid rich tissue and the major site of xenobiotic catabolism, but the concentrations have rarely been related to its capacity to produce vitellogenin or metabolise endogenous hormones. Tissue concentrations of a wide range of chemicals, are at a level which suggests that, either alone or in combination, they will cause significant endocrine disruption in fish in many polluted habitats. 

It is widely accepted that men with testicular cancer have a higher incidence of abnormalities associated with impaired spermatogenesis, both in the cancerous testis but also in the contralateral testis. Men diagnosed as having testicular cancer often have very poor semen quality, with sperm concentrations of less than 10 million/ml compared to healthy men with > 50 million/ml." It is thought that gonadal function is abnormal even before testicular cancer develops, ... 

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