Forty-three males were divided into three experimental groups and ligatures placed unilaterally as follows: (1) on the ductus deferens, (2) on the ductus deferens and corpus epididymidis, and (3) on the ductus deferens, corpus epididymidis and ductuli efferentes. Semen was collected six times a week from all males before ligation and for as long as 12 weeks thereafter. Spermatozoa transported normally from the caput to the cauda epididymidis in non-ligated controls were characterized by rapid migration of the protoplasmic droplets, a decrease in swollen acrosomes and other abnormalities, an increase in the percentage of motile cells and a striking increase in fertility. Ligation of the ductus deferens only had little effect upon any of these changes. Also, considerable motility and fertility was maintained for 12 weeks following single ligation in contrast to a reduction after 4 weeks in the group with the isolated cauda epididymidis. This suggests that considerable mixing of spermatozoa normally can occur in the cauda. The proportion of abnormal forms, particularly decapitated spermatozoa, increased considerably in the isolated cauda by 8 weeks. In the isolated caput abnormal spermatozoa increased rapidly and motility decreased. The protoplasmic droplet movement was delayed, as 54% had droplets on the midpiece after 4 weeks in contrast with 16% on spermatozoa which migrated normally to the cauda. Severe degeneration and disappearance of spermatozoa followed after 4 weeks, indicating that the caput may have dissolution properties. Litter size, based on all does inseminated, averaged only 0\m=.\5for caput spermatozoa compared with 5\m=.\0for both caudal and ejaculated spermatozoa. The morphological and fertility data indicate that extrinsic factors as well as intrinsic ones are required for complete development of the fertilizing capacity of rabbit spermatozoa.

No abstract

At many sites, anoxic conditions and dissolution of iron and manganese are already present, or are likely to develop during riverbank filtration (RBF). A prediction of iron and manganese mobilization during riverbank filtration is required to evaluate the need for further water treatment. Different methods have been tested at RBF sites in Germany: water and sediment analysis, batch and column experiments using river water, sequential extraction, and the mass balance approach. At these sites, a "wash out" effect was observed, resulting in a gradual decrease in iron concentrations between the riverbank and the abstraction well over two decades. Hydrogeochemical exchange processes in the aquifer can cause a long-term release of iron and manganese even if the organics concentration in the river water is low. Contrary to common expectations, high iron concentrations are often dominated by the portion of landside groundwater, whereas iron concentrations in bank filtrate often undergo a long-term decline.

Summary. Rabbit semen was extended in a tris-yolk-12\m=.\5% DMSO extender and frozen in liquid nitrogen vapour or on a 'dry ice' block after glycerol had been added. No differences (P>0\m=.\10) were found between inseminations with liquid semen and semen frozen in pellets with regard to the number of young born or the pregnancy rate. Other methods produced significantly (P<0\m=.\05) fewer young. Significantly (P<0\m=.\05) more young were born to does inseminated 5 hr after they received the ovulating hormone.Rabbit semen has been frozen with differing results (Smith & Polge, 1950;Fox, 1961;Fox & Burdick, 1963;Sawada & Chang, 1964;Wales & O'Shea, 1968;O'Shea & Wales, 1969). The fertility of frozen rabbit semen in the earlier reports was low. Since the ovulation time in the rabbit is known, it is a good laboratory animal in which to study the handling of spermatozoa in vitro.Two ejaculates were collected within 20 min once weekly from fourteeen White Vienna male rabbits, using an artificial vagina. Semen volume and motility per ejaculate were recorded and those having 50 % or more progressive motility were pooled. The pooled semen was diluted 1:4 with a tris-yolk dimethyl sulphoxide (DMSO) extender. The diluter was a slight modification of the tris-yolk extender reported by Steinbach & Foote (1967), having the following composition : 3-028 g tris-hydroxymethylaminomethane (C4Hj ,N03), 1-675 g citric acid (C6H807.H20), 1-250 g D-glucose (C6H1206), 15 ml DMSO and twice distilled water to make a total volume of 100 ml. To the 100 ml were added 20 ml egg yolk and 120,000 units each of penicillin and strepto¬ mycin. The pH was adjusted to 6-7 using citric acid. The sperm concentration of the extended semen was determined with a haemocytometer. The extended semen was divided into two parts and handled as follows : one part was placed in a 5°C cool room for 6 to 8 hr until it was inseminated (liquid semen) ; the other part was cooled in a 5°C cool room for 1 to 3 hr and glycerol (6% of the extender volume) was added 30 min before freezing. The extended semen containing glycerol was placed in three different forms of container: 2-5-ml plastic ampoules, 0-3 0·4 20 cm coiled polyvinylchloride tubing and 0-5-ml plastic straws, and frozen in liquid nitrogen vapour for 6 to 10 min or frozen as 0-15-ml pellets in holes on a 'dry ice' block for 10 min (frozen semen). The frozen semen was stored in liquid nitrogen until used for the inseminations.The semen in the ampoules, tubing and straws was thawed in a 40°C water 111

Ligatures were placed unilaterally on the ductus deferens (experiment l ) , on the ductus deferens and the middle of the corpus epididymidis (experiment 2) and on the ductus deferens, corpus epididymidis and ductuli efferentes (experiment 3) in 39 r,abbits. The untreated contralateral side served as a control. Vasectomy alone appeared to have no effect upon the testes, or upon spermatozoa accumulated during a period of 12 weeks proximal to the ligature. In experiment 2 severe disruption of spermatogenesis occurred. Diameter of the seminiferous tubules decreased, testes atrophied, and the stages of the seminiferous epithelium were abnormal and often not classifiable. Some regeneration was observed after 12 weeks.In experiment 3 therls was only a moderate and more transient disturbance of spermatogenesis. This occurred in spite of an accumulation of fluid in the testis due to the ligature on the Iductuli efferentes, which prevented testicular effluent from reaching the caput epididymidis. These results suggest that when testicular effluent is allowed to reach the caput, but nonresorbed residues are prevented from further transport (experiment 2), a feedback to the testis occurs which is more harmful than that produced by preventing tubular contents from leaving the testes.Although early literature is conflicting (see Poynter, '39 for refere:nces), uncomplicated vasectomy does not appear to result in testicular atrophy (Moore and Quick, '24; Young, '33; Poynter, '39; Amann, '62). However, when the epididymal lumen closer to the testes, or the ductuli efferentes are occluded by ligation, testicular damage occurs (VVagenseil, '28; White, '33; Young, '33; Harrison, '53; Baillie, '62; Glover, '62; Barack, '68; Igboeli and Foote, '68). These investigators found that there was an initial dilation of the seminiferous tubules associated with fluid accumulation, followed by varying degrees of degeneration. The testis m.ay increase in size and then atrophy. Only one report, utilizing the mouse, was found in which the effects of different levels of epididymal obstruction on testicular histology was examined quantitatively (Baillie, '62). Preliminary observations in rabbits on the frequency of seminiferous tubules in stage 8 following ligation was reported by Igboeli and Foote ('68). The latter report suggested that ligations at certain levels in the rabbit evoked considerably more trauma than in the mouse.The purpose of this study was to examine systematically and (quantitatively ANAT. REC., 164: 339-348. effects on the rabbit testis induced by obstructing the excurrent ducts at different levels. Post-operative periods were varied in length so that immediate and longerterm effects could be evaluated. MATERIALS AND METHODSThree experiments were conducted utilizing 30 mature Dutch-belted and nine New Zealand males. Ligations always were done unilaterally so that the contralateral testis could serve as a control. The side to be treated surgically was randomly assigned. The locations of the ligatures were as follows: (1 ) ...