Spermatogenesis in goats with and without scrotum bipartition.
The objective of the present research was to quantify the seminiferous epithelium cells, spermatogenesis efficiency and characterize the ultrastrucure of Sertoli cells in goats. Eighteen goats were used and divided into three groups: Group I - goats without bipartition of the scrotum; Group II - animals with bipartition of the scrotum in up to 50% of the testicular length; Group III - goats with bipartition of the scrotum in more than 50% of the testicular length. The goat testes in Group III had a greater number of primary spermatocytes (25.37 ± 4.55 cells per cross sections), spermatids (112 ± 15.12 cells per cross sections), and Sertoli cells (9.46 ± 1.74 cells per cross sections) than the animals in Groups I and II (P<0.05). The spermatogenic mitotic, meiotic, and general efficiency were greater in animals in Group III (1.25 ± 0.28; 5.12 ± 1.63; 6.44 ± 1.96) when compared to those in Groups I and II. Sheet-like processes originated from the Sertoli cell body as simple and smooth structures which involved almost all the surface of germ cells. Slender cord-like processes originated from Sertoli cells and also from the sheet-like processes. The relative frequency of the cycle stages showed differences among the groups of goats studied, and the highest frequency was in Stage 3 (20.68% for goats in Group I, 21.15% for those in Group II, and 16.89% for the animals in Group III). In conclusion, goats with bipartition of the scrotum have a greater number of germ and Sertoli cells per cross section of seminiferous tubule, that indicated a greater sperm production when compared to the other groups, and the ultrastructure of the Sertoli cell process did not present any relationship with bipartition of the scrotum.
Duration of spermatogenesis and sperm transit time through the epididymis in the Piau boar.
The Piau boar is a rustic breed of economical importance in Brazil. The duration of spermatogenesis and sperm transit through the epididymis in Piau boars was estimated using intratesticular injections of tritiated thymidine. Animals were sacrificed 1 h, 7 days, 14 days, 21 days, 34 days, and 36 days after injections. Each cycle of spermatogenesis in Piau boars lasts 9 +/- 0.2 days. At least 9 days are necessary for spermatozoa to traverse the entire epididymis. Considering that the total duration of spermatogenesis takes about 4.5 seminiferous epithelium cycles, spermatogenesis was estimated to take 40.6 days. The primary spermatocytes life span is 13.5 days, while spermiogenesis in Piau boars lasts 14.5 days. Staging in Piau boars was based on tubular morphology system. The relative stage frequencies in these boars, based on approximately 1200 seminiferous tubule cross-sections for each animal, were as follows: stage 1, 11.7 +/- 0.7%; stage 2, 14.3 +/- 0.3%; stage 3, 5.4 +/- 0.1%; stage 4, 12.1 +/- 0.6%; stage 5, 9.6 +/- 0.4%; stage 6, 17.2 +/- 0.4%; stage 7, 15.4 +/- 0.8%; and stage 8, 14.3 +/- 0.9%. The duration of spermatogenic events and the relative stage frequencies in Piau boars differ slightly from those observed in improved swine breeds.
Investigations on the rôle of organic matter in plant nutrition
1. As the result of decomposition of green manure in a swamp soil, the coarse fractions (including coarse and fine sand) of the surface layer (first 3 inches) decreased by 11·2 per cent. while the fine ones (silt+clay) increased by 9·8 per cent. in the course of 43 days. The effect was less pronounced in the manured soil maintained at 60 per cent. saturation, while no alteration was to be noticed in the case of the unmanured specimens. 2. Treatment with dilute hydrochloric acid prior to dispersion had no appreciable effect on the estimates of mechanical composition obtained in the different cases. Loss in solution was also comparatively small. 3. The silica-sesquioxide ratio increased slightly as the result of decomposition of green manure in swamp soil. The composition of the fine fractions was also altered, the total percentages of the oxides of iron, aluminium and silicon increasing from 90·5 to 99·3 in the course of 71 days. 4. The practical significance of the above and related observations has been discussed.