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C. Marion Jackson and H. Jackson

Summary. After a single dose of ethane dimethanesulphonate (EDS) (75 mg/kg) to rats the prolonged antispermatogenic action is due to a temporary elimination of the functional Leydig cell population. Replacement therapy with testosterone propionate (3 mg/day) maintains the spermatogenic epithelium but the EDS effect develops when hormone treatment is discontinued. In contrast, a short treatment with hCG (10–100 i.u./day) or LH (714 μg/day), starting before the EDS dose, permanently protects the spermatogenic epithelium. FSH treatment was completely ineffective. Although histological protection of spermatogenesis appeared complete with testosterone or hCG, effects on fertility remained but over different periods of time. Antispermatogenic and antifertility effects were produced in mice using much higher doses of EDS (5 × 250 mg/kg) but there was no protection from androgen or hCG. It is suggested that EDS binds to Leydig cells irreversibly, interfering with the action of gonadotrophin. At the dose level used the evidence suggests that the degree of reaction renders most of the Leydig cell population non-viable. A direct cytotoxic effect of the compound upon the spermatogenic epithelium might account for the inability of testosterone or hCG alone or in combination to maintain fertility at normal levels.

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PAMELA JONES and H. JACKSON

A recent publication has demonstrated the usefulness of Japanese quail in the detailed investigation of male antifertility chemicals (Jones, Kominkova & Jackson, 1972). The present study describes the effect on quail fertility of various dose levels of two compounds, busulphan (Myleran) and cyclohexane-1,4-diol dimethanesulphonate. Because of the established antispermatogonial actions of these substances in the rat, it was anticipated that an estimate of the duration of spermatogenesis in the avian species would emerge from the present work.

The fertility procedure adopted for these experiments has recently been described (Jones et al., 1972). Myleran, suspended in arachis oil, was administered to groups of four male birds as a single intraperitoneal dose or daily for 5 consecutive days. Cyclohexane-1,4-diol dimethanesulphonate (Jackson, 1971) was administered orally on 5 consecutive days in the same

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PAMELA JONES and H. JACKSON

Summary.

A test system involving fertilization in vitro of Xenopus laevis gametes was developed to study the effects of various chemosterilants on toad spermatozoa. The subsequent development of fertilized eggs indicated that effective concentrations and times of exposure were considerably greater than those likely to be achieved with antifertility doses to rodents. Low concentrations of tretamine and ethyleneurea on Xenopus spermatozoa produced high yields of abnormal embryos, whereas other epididymal sterilants active in the rat (trimethylphosphate and α-chlorhydrin) were ineffective in very high concentration. Differences between results in vitro and in vivo may be due to environmental variations or indicate an action by certain compounds on epididymal function in rodents rather than a direct action upon spermatozoa.

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H. JACKSON, C. MARION JACKSON and PAMELA JONES

For the most part, the antifertility actions of non-steroidal chemicals in male rats do not appear directly to involve the endocrine system (Jackson, 1970). In this species, administration of ethylenedimethanesulphonate (EDS) is accompanied by a temporary involution of both the ventral prostate and the seminal vesicles (Cooper & Jackson, 1970). This observation naturally led to an investigation of how far the antispermatogenic and antifertility actions of this compound involved the endocrine system, particularly the production and secretion of androgen. Treatment with EDS also inhibits the spermatogenic process in the mouse (Cooper & Jackson, 1970), in Japanese quail (Jones, Kominkova & Jackson, 1972) and in the parasitic worm, Schistosoma mansoni (Davies & Jackson, 1970).

After a single dose of the compound (75 mg/kg intraperitoneally), rats were sterile by Week 2 and remained thus for about 8 weeks

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B. N. HEMSWORTH and H. JACKSON

Summary.

Young male rats were exposed to Busulphan on selected days between the 5th day of foetal life and Day 15 post partum, inclusive. The drug apparently had no effect on the foetal sex cells when administered to the pregnant female between Days 5 and 7 post coitum. Later in pregnancy a destructive action became rapidly more powerful. The developing sex cells of the foetus were destroyed after exposure to the drug from Day 13 post coitum onwards. Supporting cells, which proliferate simultaneously with the developing sex cells, appeared to be quite indifferent to this treatment with Busulphan. Treatment during the neonatal period resulted in a selective effect on the germ cells. It was found that the sensitivity of these cells decreased rapidly after birth. The relationship between testicular damage and fertility is discussed.

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B. N. HEMSWORTH and H. JACKSON

Summary.

Female rats were exposed to Busulphan on selected days between the 5th day of foetal life and Day 15 post partum, inclusive. The drug apparently had no effect on the foetal sex cells when administered to the pregnant female between Days 5 and 7 post coitum. Later in pregnancy a destructive action became rapidly more powerful. So far as the developing ovary is concerned it would seem that the action of Busulphan at this dose level, i.e. 10 mg/kg intraperitoneally, is confined to the precursor of the oocyte, namely the oogonium and that when these cells enter meiotic prophase on about the 17th day of foetal life there is a marked decrease in their sensitivity to the action of the drug. The effect of the treatment on fertility has also been studied.

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PAMELA JONES, EVA KOMINKOVA and H. JACKSON

Summary.

The effects of several compounds of established antifertility action in male rodents have been investigated in male quail.

A short period of infertility soon followed administration of oral doses of triethylenemelamine and trimethylphosphate. Triethylenemelamine, aziridinyl urea and ethylenedimethanesulphonate by the intraperitoneal route led to infertile egg production for several weeks.

Differences between rats and quail regarding effective dose and length of sterility are discussed.

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E. R. A. COOPER and H. JACKSON

According to Wakeley (1943-44), the majority of epididymal cysts in man arise in the vasa efferentia, the bridge of tissue between the testis and epididymis. The ability of two sterilant chemicals to produce specific lesions of this nature in the rat (α-chlorhydrin—Ericsson, 1970; ethylenedimethanesulphonate—Cooper & Jackson, 1970) points to the need for further information on the vasa efferentia in relation to their susceptibility to damage in this manner. As there appears to be inadequate information on the course of these tubules, the present study was undertaken.

At post mortem, the testes resting in the scrotum of the rat present anterior and posterior surfaces and medial and lateral rounded borders. Serial longitudinal sections were made in both rat and mouse of the entire testis-epididymisvas complex, from the anterior to the posterior

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E. R. A. COOPER and H. JACKSON

Summary.

The development and fate of spermatocoeles induced in the rat epididymal pathway by giving a single dose of ethylenedimethanesulphonate has been followed histologically for almost 5 months. Many of the retention cysts, which have intact walls, resolve completely but large spermatocoeles may persist. Their content of dead spermatozoa is removed and replaced by viable spermatozoa as the testis recovers from the antispermatogenic action of the compound. The presence of such residual cysts is then compatible with normal fertility. Rupture of the cyst walls with the formation of permanent spermgranulomata sometimes occurs.

No definite relationship to the loss of androgen support induced by the compound has been found, since concurrent treatment with testosterone did not prevent the formation of lesions.

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E. R. A. COOPER and H. JACKSON

Summary.

Histological changes in the rat testis were correlated with the antifertility effects of injections of three diol diesters of methanesulphonic acid. The compounds are consecutive members of a homologous series each differing by -CH2- from its neighbours. The diester of ethylene glycol (EDS) caused antispermatogenic effects resembling those following hypophysectomy and was associated with involution of prostate and epididymis; spermatocoele formation occurred in the latter organ. Methylene dimethanesulphonate and 1,3-propylene dimethanesulphonate induced changes consistent with spermatogonial damage resembling those produced by Myleran (busulphan).