Spermatogonial stem cells: characteristics and experimental possibilities

The continuation of the spermatogenic process throughout life relies on a proper regulation of self-renewal and differentiation of the spermatogonial stem cells. These are single cells situated on the basal membrane of the seminiferous epithelium. Only 0.03% of all germ cells are spermatogonial stem cells. They are the only cell type that can repopulate and restore fertility to congenitally infertile recipient mice following transplantation. Although numerous expression markers have been helpful in isolating and enriching spermatogonial stem cells, such as expression of THY-1 and GFRalpha-1 and absence of c-kit, no specific marker for this cell type has yet been identified. Much effort has been put into developing a protocol for the maintenance of spermatogonial cells in vitro. Recently, coculture systems of testicular cells on various feeder cells have made it possible to culture spermatogonial stem cells for a long period of time, as was demonstrated by the transplantation assay. Even expansion of testicular cells, including the spermatogonial stem cells, has been achieved. In these culture systems, hormones and growth factors are investigated for their role in the process of proliferation of spermatogonial stem cells. At the moment the best culture system known still consists of a mixture of testicular cells with about 1.33% spermatogonial stem cells. Recently pure SV40 large T immortalized spermatogonial stem cell lines have been established. These c-kit-negative cell lines did not show any differentiation in vitro or in vivo. A telomerase immortalized c-kit-positive spermatogonial cell line has been established that was able to differentiate in vitro. Spermatocytes and even spermatids were formed. However, spermatogonial stem cell activity by means of the transplantation assay was not tested for this cell line. Both the primary long-term cultures and immortalized cell lines have represented a major step forward in investigating the regulation of spermatogonial self-renewal and differentiation, and will be useful for identifying specific molecular markers.     

Spermatogonial stem cells: questions, models and perspectives

This review looks into the phylogeny of spermatogonial stem cells and describes their basic biological features. We are focusing on species-specific differences of spermatogonial stem cell physiology. We propose revised models for the clonal expansion of spermatogonia and for the potential existence of true stem cells and progenitors in primates but not in rodents. We create a new model for the species-specific arrangements of spermatogenic stages which may depend on the variable clonal expansion patterns. We also provide a brief overview of germ cell transplantation as a powerful tool for basic research and its potential use in a clinical setting.     

Brain stem projections from cortical area 18 in the albino rat

Efferent brain stem projections from area 18 of the albino rat cortex were traced by autoradiography. Since results could have been compromised by spread of injected label to neighboring areas 17 and 29, studies of projections from these areas were used as controls. A hitherto unreported projection from area 18 to the thalamus in the region of its anterior nuclei was found, terminating in a roughly circular area including parts of the anteromedial, ventral, ventromedial and rhomboid nuclei. At this same level, a very light projection was seen in the contralateral anteromedial nucleus. More caudally the projection pattern was similar to that of area 17, with the lateral, lateral posterior, posterior and pretectal nuclei as targets. However, area 18 showed no projections to either division of lateral geniculate nucleus, projections which are commonly seen following injections in area 17. More caudally, the area 18 projection to the superior colliculus was confined to its four deepest laminae, a projection identical to that from areas 29c and 29b. Area 18 also resembled the cingulate cortex in that it sent a small projection to the dorsolateral central gray, although the routes taken to this region were slightly different. It was decided that the projections from this visual association area were, for the most part, unique to that area, although some of them resembled those from either the cingulate cortex or the primary visual area.     

Therapeutic effect of adipose-derived mesenchymal stem cells on Cisplatin induced testicular damage in adult male albino rat

Infertility represents a major medical, economic, and psychological problem. Stem cells therapy for infertility has a great interest nowadays especially for cancer survivors at pre-reproductive and reproductive age.

 Thirty-two adult male albino rats were used, divided equally into four groups; Group I (Control group) received isotonic saline intraperitoneally (i.p.) as vehicle. Group II (Cisplatin-treated group) received Cisplatin (i.p.) at a single dose of 7 mg/kg, and then were sacrificed after 5 days. Group III (Stem-cell-treated group) received Cisplatin (i.p.) at a single dose of 7 mg/kg, then after 5 days received adipose-derived mesenchymal stem cells (ADMSCs) (1 × 10⁶). Cells were injected in the rete testis, then after 60 days, the animals were sacrificed. Group IV (Auto healing group) received Cisplatin (i.p.) at a single dose of 7 mg/kg, and then left for 65 days then the animals were sacrificed. Cisplatin administration resulted in degenerative changes in the testicular architecture in the form of thickened irregular BM of seminiferous tubules. The germinal epithelium showed disorganization and marked reduction in the thickness, associated with Sertoli cells preservation. Features of apoptosis assured by elevated caspase-3 expression were noticed. The interstitium showed cellular infiltration and distorted Leydig cells. Injection of (ADMSCs) resulted in great improvement of testicular architecture and increase in the testosterone level associated with strong immune reaction of the CD-44. ADMSCs are recommended as a new treatment modality for male infertility.

Abbreviation: i.p.: intraperitoneally; BM: basement membrane; ADMSCs: adipose-derived mesenchymal stem cells; WHO: World Health Organization; MSCs: mesenchymal stem cells; DMEM: Dulbecco modified eagles media; PBS: phosphate-buffered saline; FACS: fluorescence-activated cell sorting; ELISA: enzyme-linked immunosorbent assay; CP: Cisplatin; ROS: reactive oxygen species; CAT: catalase; SOD: superoxide dismutase; OS: oxidative stress; SSCs: spermatogonia stem cells; GCs: germ cells; UCMSCs: umblical cord mesenchymal stem cells; TGFb1: transforming growth factor beta-1; BMP4: Bone morphogenic protein 4; BMP8b: bone morphogenic protein 8b.     

精原干细胞的生物学特性：现状、发展与应用

背景：精原干细胞具有分化、自我更新和增殖的能力,是可以实现将遗传信息稳定传递给下一代的一类成体干细胞,在医学、遗传学及动物学方面的应用前景广阔。目的：对精原干细胞的来源、生物学特性、自我更新和分化的分子调控、精原干细胞应用的相关研究成果进行了综述。方法：以“spermatogonial stem cell,biological characteristics,self-renewal,differentiation”和“精原干细胞,生物学特性,自我更新,分化”为检索词,由第一作者检索1990至2015年PubMed和中国知网数据库,查阅与精原干细胞有关的文献,最终保留46篇文献进行分析。结果与结论：精原干细胞能够进行体外培养、冷冻保存和遗传修饰及同种或异种移植,这些特性将有助于解开精子发生的机制,为雄性不育症和遗传病的治疗提供新方法,也为青年肿瘤患者因放化疗带来的生殖细胞损伤带来新的希望。精原干细胞微环境、Plzf、GDNF、SCF/c-Kit等相关信号通路对精原干细胞自我更新和分化的调控有重要作用。精原干细胞作为干细胞研究模型,将会使人们进一步了解干细胞的生物学特性,从而为医学、遗传学及动物科学方面开发奠定基础。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程 ORCID: 0000-0001-7949-8910(李兵)     

Binocular responses of cortical cells and the callosal projection in the albino rat

Four hundred and fifteen cells were recorded in the binocular segment of the visual cortex in the albino rat. Cells encountered were mainly dominated by the contralateral eye. The percentage of binocularly-driven cells increased as the electrode was moved towards the border between areas 17 and 18a. Ninety percent of the cells studied in the region of the border could be driven by electrical stimulation applied at the corresponding site in the opposite hemisphere. Within area 17, however, there were only about 30% of such cells. Through the combined use of electrical stimulation and reversible cortical cooling, two types of contributions by callosal fibres were revealed. One is that the callosal fibres constitute the only inputs from the ipsilateral eye to a cell. The other is that the callosal input provides ipsilateral reinforcement to a binocular cell. These results are compatible with neuroanatomical findings and show that binocularity of visual cortical cells in this animal depends, to a great degree, on the function of callosal fibres.     

DNA content in atypical glio-mesenchymal cells during chemical carcinogenesis in the albino rat cerebellum

The DNA content was determined by comparative microspectrophotometry in atypical glio-mesenchymal cells around the villous capsule surrounding the DMBA pellet, and in cells of microastrocytomas and microglioblastomas induced by DMBA. A characteristic feature of the late stages of this type of chemical carcinogenesis in the albino rat cerebellum was found to be the preservation of a well-marked diploid modal class, except in cases when the pathological process developed along malignant lines in the early stages of tumor progression (microglioblastoma).     

DNA synthesis in various cells of the exocrine part of the intact albino rat pancreas

A differential count was made of the DNA-synthesizing cells in various parts of the exocrine epithelium of the intact pancreas of sexually mature male albino rats sacrificed 1 h after a single injection of thymidine-H³. The acinar cells showed low proliferative activity (0.18±0.05%). The highest labeling index was found in the epithelium of the ducts. However, the lining membrane of the ducts consisted of a heteromorphic system of cells with a varying level of DNA synthesis. The labeling index of the nuclei of the centroainar cells was 2.5 times higher than that of the acinar epithelium and amounted to 0.48±0.17%, whereas the epithelium of the intercalary ducts had an extremely low labeling index: 0.09±0.09%, compared with 0.27±0.09% for the intralobular ducts and 0.50±0.08% for the interlobular ducts.     

干细胞相关因子在大鼠卵巢颗粒细胞中的表达

背景：现有研究表明,人与大鼠卵巢优势卵泡中的颗粒细胞具有表达干细胞特性的现象。 目的：探讨干细胞相关因子在大鼠卵巢颗粒细胞中的表达。 方法：将大鼠卵巢组织制作石蜡切片后,使用免疫组化法检测CD34,CD133,ABCG2/Bcrp1,Pou5f1/Oct-4的表达。卵泡穿刺法获取颗粒细胞,并使用免疫组化法检测FSHR受体的表达以鉴定颗粒细胞的纯度。免疫组化法检测颗粒细胞CD44,C-Kit的表达情况,RT-PCR检测卵巢组织与颗粒细胞ABCG2/Bcrp1、Pou5f1/Oct-4、Nanog基因的表达情况。 结果与结论：免疫组化法石蜡切片显示部分卵巢颗粒细胞CD34,CD133,ABCG2/Bcrp1,Pou5f1/Oct-4阳性表达,而Pou5f1/Oct-4蛋白的表达在卵泡发育的周期中逐步增多,并在黄体化的时候显著增强,形成白体后则消失,因而具有周期性表达的特点。卵泡穿刺法提取的原代颗粒细胞FSHR受体鉴定阳性率在95%以上。体外培养的颗粒细胞以长梭形或菱形为主,部分细胞有聚集生长现象,且CD44,C-Kit阳性表达。RT-PCR检测结果显示,卵巢组织与体外培养的颗粒细胞均不表达Nanog,卵巢低表达Pou5f1/Oct-4,强烈表达ABCG2/Bcrp1,颗粒细胞微弱表达Pou5f1/Oct-4,而ABCG2/Bcrp1表达较强。以上结果显示大鼠卵巢中的部分颗粒细胞具有干细胞的特性。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

Two somatic eyelid reflexes in the albino rat

Eyelid responses to air puffs directed at the cornea of the rat are shown to result from the activation of two reflexes. A brief early component of the response results from stimulation of the eyelids, especially the eyelashes. The larger, later component is initiated by stimulation of the cornea. Branches of the trigeminal nerve comprising the afferent limbs of the two reflexes were identified in physiological experiments by selective denervation of the upper eyelid, the lower eyelid, or globe, and by anatomical procedures. Responses of single orbicularis oculi motoneurons, recorded from a dorsal group of cells in the facial nucleus, indicate that both reflexes are served, in part at least, by the same motoneurons. A pause of contraction in responses to air puffs when spontaneous activity is present suggests that orbicularis oculi has Golgi tendon organs. The early response of the eyelash reflex habituates and differs in this respect from the early component of the human orbicularis oculi reflex.     

Therapeutic effect of mesenchymal stem cells on experimentally induced hypertensive cardiomyopathy in adult albino rats

Hypertensive heart diseases affect millions of people worldwide. We aimed to investigate the hypertensive left ventricular histological changes and assess the effectiveness of bone marrow derived mesenchymal stem cells (MSCs) therapy in the treatment of hypertensive cardiomyopathy. Adult male albino rats were assigned into two groups: group I (control), group II (Experimental) subdivided into subgroup IIa (hypertensive) and subgroup IIb (stem cell therapy). Left ventricles (LVs) were processed for light and electron microscope. Mallory’s trichrome and immunostaining for caspase-3 and desmin were carried out. Hypertension caused left ventricular histological and immunohistochemical changes that had been effectively improved by MSCs therapy.     

Development of the definitive kidney in albino rat

The current understanding of the kidney development in the pelvis and then a subsequent migration to the lumbar region is disputed. A total of 96 embryos were examined after they were obtained from 24 pregnant rats. A group of 4 pregnant rats were sacrificed at each day over the period from 12 to 17 successive days of pregnancy. An almost equal number of embryos were histologically investigated at each day using the paraffin technique. This was fulfilled by taking serial sections throughout the entire length of the trunk. The 13 days old embryo presented the appearance of the definitive kidney as indicated by the microscopical display of the ureteric bud invading the nephrogenic cord. This microscopic event took place at the lower lumbar region of all examined embryos. Therefore, the present work gives a microscopic evidence that the definitive kidney develops in the lumbar region.