Cell-cycle-dependent Colonization of Mouse Spermatogonial Stem Cells After Transplantation into Seminiferous Tubules

Spermatogonial stem cells (SSCs) migrate to the niche upon introduction into the seminiferous tubules of the testis of infertile animals. However, only 5–10% of the transplanted cells colonize recipient testes. In this study, we analyzed the impact of cell cycle on spermatogonial transplantation. We used fluorescent ubiquitination-based cell cycle indicator transgenic mice to examine the influence of cell cycle on SSC activity of mouse germline stem (GS) cells, a population of cultured spermatogonia enriched for SSCs. GS cells in the G1 phase are more efficient than those in the S/G2-M phase in colonizing the seminiferous tubules of adult mice. Cells in the G1 phase not only showed higher expression levels of GFRA1, a component of the GDNF self-renewal factor receptor, but also adhered more efficiently to laminin-coated plates. Furthermore, this cell cycle-dependency was not observed when cells were transplanted into immature pup recipients, which do not have the blood-testis barrier (BTB) between Sertoli cells, suggesting that cells in the G1 phase may passage through the BTB more readily than cells in the S/G2-M phase. Thus cell cycle status is an important factor in regulating SSC migration to the niche.     

Morphology and Morphometry of Seminiferous Tubules in Crioulo Horses

This study aimed to assess the biometrics of the testes and the morphology of the seminiferous tubules of Crioulo horses. We studied 10 sexually mature stallions (3–6 years of age). After orchiectomy, testes were perfused with Karnovsky's solution and then embedded in glycol methacrylate. Testis sections (4 μm) were cut and stained with toluidine blue and a solution of 1% sodium borate. The histological images were digitized, and the morphometric analysis was performed using ImageJ software. The average weight of the stallions was 377.5 kg, and the average weight of both testicles was 162.9 g. The percentage of testicular parenchyma occupied by the seminiferous tubules and the intertubular tissue was 77.97% ± 6.34% and 22.03% ± 6.34%, respectively. The average tubular diameter was 205.00 ± 36.91 μm, whereas the average height of the seminiferous epithelium was 70.56 ± 2.82 μm. Average tubular length per testicle and average tubular length per gram of testicle were 4,085.10 ± 1,170.68 m and 26.09 ± 10.63 m/g, respectively. The characteristics of the eight stages of the seminiferous epithelium cycle were similar to those reported in other horse breeds. We conclude that the morphometry of the seminiferous tubules of Crioulo horse resembles what has been reported in other horse breeds. The volumetric proportion of the seminiferous tubules and the Leydig cells of the Crioulo horse is one of the highest ever reported for stallions.     

成年小鼠生精小管及睾丸的冷冻保存

采用含不同浓度抗冻剂二甲基亚砜(DMSO)、乙二醇(EG)、丙二醇(PG)及丙三醇(G)的DMEM培养基作为冻存液,对成年小鼠生精小管及完整睾丸进行慢速冷冻,液氮保存,37 ℃水浴复苏,并测定细胞复苏率。结果表明,成年小鼠生精小管在50 mL/L、100 mL/L 及150 mL/L DMSO冻存液中的细胞复苏率分别为92.6%、93.4%及69.4%,在50 mL/L、100 mL/L及150 mL/L PG 冻存液中的细胞复苏率分别为94.2%,93.3%及66. 9%,在50 mL/L、100 mL/L 及150mL/L EG 冻存液中的细胞复苏率分别为87.2%、91. 0%及62. 6%,在50 mL/L、100mL/L及150 mL/L G冻存液中的细胞复苏率分别为90.0%、90.5%及67.1%。各种抗冻剂的最高细胞复苏率之间差异不显著(P> 0. 05 )。成鼠完整睾丸在含100 mL/LDMSO、PG、EG或G的冻存液中的细胞复苏率分别为56.0%、50.0%、50.2%及50.2%。结果显示,DMSO、PG、EG 及G 均适宜用作成年小鼠生精小管的抗冻剂,最佳使用浓度均为50 mL/L~100 mL/L。完整睾丸冷冻后的细胞复苏率低于60%,仍需进一步研究。     

Ultrastructure of the Bull Seminiferous Tubule Supporting Cells with Special Consideration of the Cell Junctions

This study represents an electronmicroscopic examination of seminiferous tubule epithelium of the bull, with special attention to the cell types and junctional complexes between cells which contribute to the blood-testis barrier. In general seminiferous epithelium of the bull resembles that of other animals with some alterations in supportive cell types and organization of junctional complexes between epithelial cells. These differences are illustrated and discussed in regard to their possible functional significance.     

Sexual Maturation in the Bull

In this review, we describe the process of sexual maturation in the bull calf. The testes of the bull grow relatively slowly until approximately 25 weeks of age and then a rapid phase of growth occurs until puberty, at 37–50 weeks of age. During the early postnatal phase of slower growth of the testis pre-spermatogonia and some spermatogonia are established, adult Leydig cells appear and undifferentiated Sertoli cells are produced. The rapid testicular growth, after 25 weeks of age, consists of marked increases in the diameter and length of the seminiferous tubules, dramatic proliferation and differentiation of germ cells, with mature spermatozoa occurring between 32 and 40 weeks of age. The adult Leydig cell population is largely in place by 30 weeks of age and that of Sertoli cells by 30–40 weeks of age. Serum concentrations of LH increase from 4 to 5 weeks of age, to an early postnatal peak at 12–16 weeks of age, followed by a decline to 25 weeks of age. Serum FSH concentrations are high postnatally, declining to approximately 25 weeks of age. Serum testosterone concentrations increase during the phase of rapid testicular growth. Hypothalamic opioidergic inhibition may abate transiently to allow the early postnatal increase in LH secretion, while testicular androgenic negative feedback probably contributes to the decline in gonadotropin secretion to 25 weeks of age. Several lines of study have led us to suggest that early postnatal gonadotropin secretion is pivotal in initiating the process of sexual maturation in the bull calf.     

Regulation of the Spermatogonial Stem Cell Niche

Spermatogonial stem cells (SSCs) reside within specialized microenvironments called 'niches', which are essential for their maintenance and self-renewal. In the mammalian testis, the main components of the niche include the Sertoli cell, the growth factors that this nursing cell produces, the basement membrane, and stimuli from the vascular network between the seminiferous tubules. This review focuses on signalling pathways maintaining SSCs self-renewal and differentiation and describes potential mechanisms of regulation of the spermatogonial stem cell niche.     

7日龄小鼠生精上皮单细胞冷冻保存

在DMEM中添加10％小牛血清（NBS），并分别添加不同浓度的抗冻剂二甲基亚砚（DMSO）、丙二醇（PG）、乙二醇（EG）及甘油（G），对7日龄小鼠生精上皮单细胞进行冷冻保存，复苏后台齿蓝染色测定细胞复苏率。结果：当冻存液中DMSO分别为5％、10％、15％、20％时，细胞复苏率分别为77．1％、88．2％、86．5％、73．5％、65．5％，其中10％和15％DMSO组细胞复苏率最高，与其作各组间均差异极显著（P＜0．01）。当冻存液中PG分别为5％、10％、15％、20％、25％时，细胞复苏率分别为66．2％、84．3％、72．1％、69．9％、47．5％，其中10％PG组细胞复苏率最高，与其余各组间均差异极显著（P＜0．01）。当冻存液中EG分别为5％、10％、15％、20％时，细胞复苏率分别为64．9％、81．6％、60．9％、44．7％，其中10％EG组细胞复苏率最高，与其余各组间均差异极显著（P＜0．01）。当冻存液中G分别为5％、10％、20％、25％时，细胞腹苏率均低于10％。10％DMSO组细胞复苏率与10％PG组和10％EG组之间均差异显著（P＜0．05）或极显著（P＜0．01）。结果表明，10％DMSO、10％PG及10％EG均适宜冷冻保存小鼠精原细胞，以及10％DMSO的冻存效果最好，而则不适宜冷冻保存。在含10％DMSO的冻存液中，二步慢速冷冻，液氮储存，37C水浴复苏小鼠精原细胞，是一种具有较高细胞复苏率的冷冻保存方法。     

家蚕马氏管组织构造的研究

通过对家蚕 (Bombyxmori) 5龄第 5日幼虫马氏管外部形态和内部组织结构的观察 ,发现不同部位马氏管的结构差异很大 :膀胱呈囊状体开口于小肠两侧 ,肌肉层厚、细胞层较薄 ,内腔很大 ;下行管靠膀胱处圆形 ,较膨大 ,其余大部分外型呈扁平形且表面光滑 ,细胞层较薄 ,内缘有微绒毛状突起、管腔较大 ;上行管前部管体稍扁平 ,结构与下行管相似 ,中后部管体圆形、细胞层肥厚、内缘呈蜂窝状、管腔狭小 ;隐肾管的外列马氏管细胞层薄、管腔较大 ,而内列马氏管细胞层肥厚、管腔很小。马氏管结构的差异与各部位的功能有密切关系。     

Evaluation of Breeding Value and Selection of Bull Dams in the Danish Dairy Breeds: I. Studies on Realized Efficiency of Bull Dam and Bull Sire Selection

Abstract

The relationship between twice the adjusted daughter yield deviation (DYD) of the son and the average of the estimated breeding values (EBV) of his parents was investigated for milk and fat yield. Deviations from expectations of DYD minus the pedigree index and the regression of DYD on the EBV for each of the parents were estimated. The EBV of each bull dam was calculated in several ways using different combinations of pedigree information and their own records. In all, 1693 bulls (880 Black and White (BW), 418 Red Danish (RD) and 395 Danish Jersey (DJ)) with Direct Updating indices for milk and fat yield were included in the investigation. Mean discrepancies between estimated and observed genetic merit for kg of milk yield were ?348 for BW, ?213 for RD and ?228 for DJ, when all of the bull dams' individual records were utilized in breeding value estimation. The corresponding mean discrepancies for kg of fat yield were ?14.7, ?11.5 and ?11.9, respectively. The discrepancies were positively correlated with the number of lactation records included in the dams' EBVs. Regression coefficients of bull DYDs on bull dam breeding values were significantly lower than expected for RD and BW regardless of the number of individual lactation records included in the dams' indexes for milk and fat yield. For all three breeds, the regression coefficients were lowest for fat yield. The most probable cause of overestimation in bull dam EBVs is preferential treatment, particularly in second and later lactations. To avoid this bias, estimation of a bull dam's breeding value should be based on pedigree information and on records from only her first lactation.     

The Effect of Copper from Industrial Emission on the Seminiferous Epithelium in Rams

Contents: The changes in the testes of adult rams have been followed by methods of light-and electronmicroscopy after intoxication with copper emitted from a copper plant. In the toxic phase of the disease primarily the germinative epithelium was damaged. The breaking or decay of the cellular membrane with consequent devastation or stagnation of the spermiogenesis was observed. The toxic effect of the copper affects irreversibly not only all the cells of spermiogenesis in the developmental stages, but it damages also the Sertoli cells including the components of the interstitium. These changes participated in the impairment of reproduction in the flock under study.     

哺乳动物精原干细胞研究进展

自Brinster等人异体（种）移植小鼠和大鼠精原干细胞取得成功以来，精原干细胞已成为干细胞领域内的一个新的研究热点，由于它在人类医学，畜牧业，濒危动物保护及转基因动物生产等方面的潜在用途，精原干细胞很可能成为一种极为有用的生物工具，本文不其生物学特性，分离、鉴定及应用前景等综述如下。     

牛冷冻精液的应用研究进展

牛人工授精技术是所有家畜中应用最为广泛的一种繁殖技术,而其巨大的发展又得益于精液冷冻保存的成功应用.本文简要介绍了牛精液冷冻技术的发展历史和精液冷冻的原理,分析了影响牛精液冷冻效果的主要因素,并对国内外现行使用的精液评定指标作了简单阐述,以期为牛高质量冷冻精液的研究和牛人工授精技术的应用提供参考.     

奶牛冷冻稀释液研究进展

为了提高冻精质量,人们对稀释液进行了大量科学试验,获得许多重要成果.本文综述了奶牛冷冻精液稀释液的研究进展,为进一步研究稀释液和精子之间的相互关系及新型冷冻稀释液的开发和利用提供参考.     

种公牛站的发展机遇与挑战

种公牛站是畜牧业良种繁育体系的重要组成部分,是我国法定的牛冷冻精液生产和经营单位。随着国外育种公司、种子资源的逐步进入,对国内种公牛站现有的生产技术水平和经营管理水平带来新的考验,竞争也会越加激烈。所以要尽快提高我国种公牛站整体生产和经营水平,以适应畜牧业发展和结构调整的需要及增强国内外市场竞争力。     

Regularities and Irregularities in the Structure of the Seminiferous Epithelium in the Domestic Fowl (Gallus domesticus)

A cellular association demarcated by two perpendiculars which were drawn between adjacent bundles of elongate spermatids from the tubular lumen to the basement membrane, was made the unit of histometrical observation in this study (provisionally called a “column”). Cell counting revealed that the average numbers per column of various types of germ cells do not show any significant differences among 5 fowls and between paired testes. The frequency of spermiogenic steps (numbered 1–8) was investigated in each column. A definite and common pattern was found in the frequency distribution in the 5 fowls observed. A relationship between spermiation and younger spermatid steps was also investigated in each column. The spermiation was found at different steps, but most frequently at step 2 (30.6 %). Based on these observations and referring to other author's information, an average time interval between two successive spermiations was calculated roughly at 3.3 ± 1.2 days. Theoretically, this value is equal to an average length of one epithelial cycle. Such a variable cycle may have caused irregular cellular associations in this species.