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  • Author: B. G. Crabo x
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M. S. Kosco, K. J. Loseth and B. G. Crabo

Summary. Development of the prepubertal seminiferous tubules of the right testis was characterized morphometrically every 14 days from 10 to 122 days of age in intact boars (I) and boars hemicastrated (HC) on Day 10 of life from two herds (Trial 1 and Trial 2). Comparisons were made between the remaining testis of Group HC boars and one testis in Group I boars. By 38 days of age seminiferous tubule length in Group HC boars was double (P < 0·0001) that in Group I boars. Seminiferous tubule length did not differ between trials within treatments. The diameter of the seminiferous tubule was similar in Group HC and I boars but was greater (P < 0·05) in Trial-1 than Trial-2 boars from Day 80 to 122 of life. Relative mass (mass of tissue/body mass) of Sertoli cells became 2-fold greater (P < 0·0001), in Group HC than in one testis of Group I boars by 38 days of age and this difference was maintained throughout the experimental period. The relative mass of Sertoli cells was greater (P < 0·05) in Trial-1 than Trial-2 boars within each treatment between 80 and 122 days of age. The relative mass of gonocytes was similar for all groups and treatments of boars. By 122 days of age the relative mass of spermatogenic cells was greater (P < 0·05) in Group HC than in one testis of Group I boars and greater (P < 0·01) in Trial-1 than Trial-2 boars within each treatment. Onset of spermatogenesis was first observed at 80 and 94 days of age in boars in Groups HC and I, respectively. Development of seminiferous tubule lumen was first observed at 94 and 108 days of age in boars in Groups HC and I respectively. Seminiferous tubule lumen, taken as a measure of fluid secretion of the Sertoli cells, occupied a greater (P < 0·01) portion of seminiferous tubule in Trial-1 than Trial-2 boars within each treatment at the end of the experimental period. It is concluded that neonatal hemicastration of boars rapidly caused a compensatory seminiferous tubule elongation apparently due to Sertoli cell proliferation and an earlier onset of spermatogenesis. However, the gonocytes do not proliferate until they transform into spermatogonia.

Keywords: boar; testis; hemicastration; seminiferous tubule; spermatogenesis

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M. S. Kosco, K. J. Loseth and B. G. Crabo

Summary. Development of the prepubertal interstitium of the right testes was characterized every 14 days from 10 to 122 days of age in intact boars (I) and boars hemicastrated (HC) at 10 days of age from two herds (Trial 1 and Trial 2). Comparisons were made between the remaining testis of Group-HC boars and one testis in Group-I boars. The relative mass (mass of component/body mass) of interstitium was 151% greater (P < 0·001) in Group-HC than Group-I boars by 52 days of age. The relative mass of interstitium was greater (P < 0·01) in Trial-1 than Trial-2 boars within each treatment from 80 to 122 days of age. The relative mass of interstitial space was 76% greater (P < 0·05) in Group-HC than in one testis of Group-I boars by 52 days of age and greater (P < 0·05) in Trial-1 than Trial-2 boars within each treatment from 80 to 122 days of age. The relative mass of Leydig cells was 254% greater (P < 0·0001) in Group-HC than Group-I boars by 52 days of age and remained greater (P < 0·05) in Group-HC than Group-I boars from 52 to 122 days of age. By 52 days of age the relative mass of Leydig cell nuclei and cytoplasm was 235% and 265% greater (P < 0·0001) in Group-HC than Group-I boars, respectively, and both remained greater (P < 0·05) in Group-HC than in Group-I boars until 122 days of age. The relative mass of small vessels was 86% greater (P < 0·01) in Group-HC than Group-I boars from 24 to 66 days of age and was similar in Group-I and Group-HC boars from 66 to 122 days of age. The relative mass of Leydig cells, nuclei and cytoplasm as well as small vessels was similar between trials of boars within each treatment. Neonatal hemicastration of boars at 10 days of age therefore resulted in an overcompensation in numbers of Leydig cells, measured as nuclear mass, whereas the increase in vascular development and interstitial space did not fully compensate the loss of testicular tissue. The cytoplasm to nuclear ratio reflected the steroid production of the Leydig cells which was related to pubertal tubular development rather than treatment.

Keywords: boar; testis; hemicastration; interstitium; Leydig cell

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K. J. Rozeboom, M. H. T. Troedsson and B. G. Crabo

The objective of this study was to characterize the uterine leukocyte influx after artificial insemination (AI). After detection of oestrus with a boar at intervals of 1.5 h, seventy-two gilts were randomly assigned to a 2×3×4 factorial arrangement. AI was performed with 100 ml extended semen containing 5 × 109 spermatozoa (semen; n = 36) or 100 ml VSP semen extender (extender; n = 36) at one of three times after detection of oestrus: 12, 24 or 36 h (n = 24/time). The uterus was lavaged at 6, 12, 18 or 24 h (n = 18/time) after AI to determine the total number of uterine leukocytes. In addition, uterine lavage was performed on nine untreated gilts immediately after the detection of oestrus to establish a baseline number of leukocytes. The leukocyte response in all samples consisted predominately (92–99%) of polymorphonuclear neutrophilic granulocytes (PMNs). The mean number of PMNs recovered from the uteri of gilts treated with semen was greater than in gilts treated with extender and in untreated gilts (P < 0.01). The greatest number of PMNs in semen-treated gilts was found 12 h after AI (P < 0.01), and this number was sustained for 24 h. In contrast, the number of uterine PMNs recovered from extender-treated gilts reached a peak at 6 h and had declined by 12 h after AI (P < 0.05). It was concluded that an extensive influx of PMNs into the uterus is a normal sequence to AI. The consequences and importance of semen-induced uterine leukocytosis needs further investigation.

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R. S. Jeyendran, H. H. Van der Ven, M. Perez-Pelaez, B. G. Crabo and L. J. D. Zaneveld

Summary. The objective of this study was to develop a relatively simple test to evaluate the functional integrity of the membranes of human spermatozoa. As in some other species, human spermatozoa 'swell' under hypo-osmotic conditions due to the influx of water and the expansion of the membranes. A mixture of equal parts of fructose and sodium citrate (150 mosmol) with calculated ionic strength of 0·15 resulted in a maximal number of clearly identifiable swollen spermatozoa. Only small variations were seen when different aliquants of the same semen samples were separately evaluated. A high correlation (r = 0·94) was obtained between expected and observed values of swollen spermatozoa when known amounts of heat-treated spermatozoa, unable to undergo swelling, were added to untreated spermatozoa. A good correlation (r = 0·90) was also observed between the % spermatozoa in a semen sample that were capable of undergoing swelling and the % of denuded hamster oocytes that were penetrated by capacitated spermatozoa from the same semen sample. By contrast, the correlations between % sperm swelling in ejaculates and % normal sperm forms, % motile spermatozoa and % spermatozoa that do not stain with eosin-Y (supravital stain) in the same ejaculates were 0·30,0·61 and 0·52, respectively. Therefore, the hypo-osmotic swelling technique to evaluate the functional integrity of the sperm membrane appears to give high repeatability and accuracy and is closely correlated to the in-vitro fertilizing ability of spermatozoa. It may be a useful addition to the standard semen analysis.