A comparison of the leech Theromyzon tessulatum angiotensin I-like molecule with forms of vertebrate angiotensinogens: a hormonal system conserved in the course of evolution

After five steps of purification including gel permeation, anti-angiotensin I affinity column chromatography followed by reverse-phase HPLC, a peptide immunoreactive to two different antisera (anti-angiotensin I) was purified to homogeneity from extracts of the leech Theromyzon tessulatum. The first 14 amino acid residues of the purified peptide (DRVYIHPFLLXWG) established by automated Edman degradation, reveal the existence in leeches of an angiotensin I-like molecule close to human angiotensin I. The sequence of the purified peptide presents 78.5% of homology with the N-terminal part of human angiotensin. Moreover, in its sequence, this peptide presents the cleavage sites of vertebrate angiotensin metabolic enzymes, i.e. the renin and the angiotensin-converting enzyme. This finding constitutes the first biochemical characterization of an angiotensin I in Invertebrates. It also reflects the high conservation of angiotensins in the course of evolution, suggesting a fundamental role of this family in fluid homeostasis.     

Glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes in dogs infected with canine distemper virus

An experiment based on astrocyte immunoreactivity to glial fibrillary acidic protein (GFAP) was designed to determine whether the astrocyte response in canine distemper encephalitis (CDE) was associated with the age of the animal, type of lesion and the cerebellar region affected. Four histopathological types of CDE lesion were examined, namely acute (11 dogs), acute with necrosis (four dogs), subacute (22 dogs) and chronic (six dogs). The animals were divided into three age groups, namely, 0-2 years (27 dogs), 2.1-4 years (12 dogs), and 4.1-12 years (four dogs). Three different cerebellar regions were evaluated. Cerebellar sections from three healthy dogs were used for control purposes. The highest number of astrocytes occurred in the cerebellar white matter and in dogs with acute distemper encephalopathy. In animals with subacute distemper encephalitis, the numbers of astrocytes appeared to increase with age, but the opposite effect occurred in dogs with acute or chronic encephalitis; age appeared not to influence the astrocyte numbers in dogs suffering from acute encephalitis with necrosis.     

Distribution of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes in the rat brain

In the first of two papers dealing with the distribution of glial fibrillary acidic protein-(GFAP)-immunoreactive elements in the rat brain, the localization of immunostaining in the forebrain is systematically described. While the limbic cortex was found to contain intensely stained, evenly distributed astrocytes, the neocortex showed clearly stratified GFAP-staining, with substantially less immunoreactivity occurring in the middle layers than in the areas close to the brain surface or the white matter. A remarkably regular staining pattern was observed in the hippocampus and dentate gyrus. The striatum remained unstained in sharp contrast to the pallidum. In the diencephalon, the main thalamic nuclei were poor in GFAP-labelled elements in contrast to the internuclear border zones. In the hypothalamus, nuclei were conspicuous by their GFAP-staining. A consistent differential staining pattern was obtained in the epithalamic structures. The observed distributional pattern of diencephalic GFAP-immunoreactivity is thought to be due to different regional proliferation of the embryonic neuroepithelium of the diencephalon. The uneven distribution of GFAP-immunoreactivity in the forebrain is explained on a mainly developmental basis.     

Distribution of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes in the rat brain

Summary The topographical mapping of glial fibrillary acidic protein (GFAP)-immunoreactivity was performed in coronal serial sections of the rat mesencephalon, rhombencephalon and spinal cord. Relative to a background of poor or moderate overall staining of the mesencephalon, the interpeduncular nucleus, substantia nigra and the periaqueductal grey matter were prominent by their intense GFAP-immunoreactivity. The pons and particularly the medulla contained more GFAP-labelled elements compared with the mesencephalon. The spinal trigeminal nucleus and Rolando substance were distinguished by their intense staining. Large fibre tracts were usually poor in immunoreactive GFAP. In a concluding discussion, findings relevant to the GFAP-mapping of the whole rat CNS are evaluated with regard to possible reasons underlying the observed differential distribution of GFAP-immunoreactivity.     

Glial fibrillary acidic protein (GFAP)-like immunoreactivity in normal and transected rat olfactory nerve

Summary Normal and transected rat olfactory nerves were stained immunohistochemically using a monoclonal antibody previously shown to selectively detect GFAP-like immunoreactivity in central astrocytes but not in peripheral Schwann cells. Low levels of central type GFAP were found in the olfactory nerves, presumably in ensheathing cells. The levels of GFAP increased dramatically after nerve transection. A population of strongly GFAP-positive cells was detected at the junction between the olfactory epithelium and initial part of the nerves, of possible relevance to the regenerative abilities of this pathway.     

Glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes are increased in the hypothalamus of androgen-insensitive testicular feminized (Tfm) mice.

In the hypothalamus of androgen-insensitive testicular feminized (Tfm) mice the normal pattern of immunohistochemical staining for glial fibrillary acidic protein (GFAP) is markedly different from normal. Along the borders of the third ventricle and in the dorsomedial and arcuate nuclei, the numbers of stained astrocytes are increased. The usual ordered array of tanycytic processes is obscured by a tangle of GFAP-stained stellate glial cells. GFAP immunostaining in other regions of the Tfm forebrain is similar to that in normal mice. These results suggest that the distribution of reactive glia in the hypothalamus may have been changed as a consequence of the genetic defect in Tfm mice.     

Glial fibrillary acidic protein in cryogenic lesions of the rat brain

Histologic sections of rat brains obtained at time intervals ranging from 30 min to 48 h following a cryogenic lesion placed on the surface of the parietal lobe, were immunocytochemically stained for glial fibrillary acidic (GFA) protein (glial filaments), IgG and albumin. Intense staining for the GFA protein and enlargement of astrocytes in the subcortical white matter and corpus callosum, were demonstrated near the lesion at 30 min and spread throughout the white matter up to 48 h. The early reaction of the astrocytes suggests that disassembly of glial filaments or new GFA synthesis may contribute to astrocytic changes.     

Immunohistochemical demonstration of glial fibrillary acidic protein (GFAP) in nasal gliomas

Using the Sternberger method (Immunoluk Histoset KIT) GFAP (glial fibrillary acidic protein) was demonstrated immunohistochemically in 4 nasal gliomas. In these histologically complex tumour-like lesions mesenchymal, epithelial, and neuroglial tissues as well as small groups of scattered glial elements could be differentiated specifically by the highly sensitive GFAP immunoperoxidase technique. GFAP was present in astrocytes and astrocyte-like differentiations. The reactivity of cell processes was essentially lower. The GFAP immunostain does not always correlate with Mallory's phosphotungstic acid hematoxylin (PTAH) stain and Gallyas' silver impregnation method for astrocytes. Additionally the immunohistochemical investigation of semithin sections prepared by the so-called pop off technique after Bretschneider et al. (1981) allows the correct localization of GFAP in astrocytes and their modulations. Furthermore, in this study, the intimate connection of epithelium and glial cells as well as astrocytes containing hemosiderin granules could be demonstrated. The latter findings suggest a possible phagocytotic activity of astrocytes. Our results show that the demonstration of GFAP by the Sternberger method is a valuable aid in establishing astrocytic glial differentiations and modulations in complex tumour-like lesions such as nasal gliomas.     

宫内感染后低龄大鼠脑组织中胶质纤维酸性蛋白的表达变化

目的:探讨胶质纤维酸性蛋白(GFAP)在宫内感染后低龄大鼠脑组织中的表达变化及其意义。方法: 对孕大鼠子宫内注入大肠杆菌建立宫内感染的大鼠模型,以子宫内注入生理盐水为对照组。两组分别于生后1、3、7、14及21 d取幼鼠脑组织,应用免疫组化方法检测脑组织中不同脑区GFAP的表达。结果: 生后1、3 d龄大鼠仅脑室旁白质区可见少许GFAP阳性细胞,两组细胞数无显著差异(P>0.05),其余脑区未见明显GFAP表达。感染组7日龄大鼠脑室旁白质和海马区GFAP阳性细胞数增多,与对照组比较差异显著(脑室旁白质区:9.73±3.55 vs 5.67±1.90,P<0.05;海马区:7.81±3.61 vs 2.16±1.11,P<0.05)。感染组14 d龄大鼠脑室旁白质、胼胝体及皮层区GFAP阳性细胞数增多,与对照组比较均有显著差异(脑室旁白质区:12.72±1.81 vs 9.00±0.93,P<0.01;胼胝体区:10.98±3.26 vs 4.44±1.15,P<0.01;皮层区:5.43±1.79 vs 2.71±0.67,P<0.01)。两组21 d龄大鼠各脑区GFAP阳性细胞数无显著差异(P>0.05)。结论: 宫内感染后低龄大鼠脑组织中GFAP表达增加。     

Characterization of glial fibrillary acidic protein (GFAP)-expressing hepatic stellate cells and myofibroblasts in thioacetamide (TAA)-induced rat liver injury

Hepatic stellate cells (HSCs), which can express glial fibrillary acidic protein (GFAP) in normal rat livers, play important roles in hepatic fibrogenesis through the conversion into myofibroblasts (MFs). Cellular properties and possible derivation of GFAP-expressing MFs were investigated in thioacetamide (TAA)-induced rat liver injury and subsequent fibrosis. Seven-week-old male F344 rats were injected with TAA (300 mg/kg BW, once, intraperitoneally), and were examined on post single injection (PSI) days 1–10 by the single and double immunolabeling with MF and stem cell marker antibodies. After hepatocyte injury in the perivenular areas on PSI days 1 and 2, the fibrotic lesion consisting of MF developed at a peak on PSI day 3, and then recovered gradually by PSI day 10. MFs expressed GFAP, and also showed co-expressions such cytoskeletons (MF markers) as vimentin, desmin and α-SMA in varying degrees. Besides MFs co-expressing vimentin/desmin, desmin/α-SMA or α-SMA/vimentin, some GFAP positive MFs co-expressed with nestin or A3 (both, stem cell markers), and there were also MFs co-expressing nestin/A3. However, there were no GFAP positive MFs co-expressing RECA-1 (endothelial marker) or Thy-1 (immature mesenchymal cell marker). GFAP positive MFs showed the proliferating activity, but they did not undergo apoptosis. However, α-SMA positive MFs underwent apoptosis. These findings indicate that HSCs can proliferate and then convert into MFs with co-expressing various cytoskeletons for MF markers, and that the converted MFs may be derived partly from the stem cell lineage. Additionally, well-differentiated MFs expressing α-SMA may disappear by apoptosis for healing. These findings shed some light on the pathogenesis of chemically induced hepatic fibrosis.     

Altered pattern of immunohistochemical staining for glial fibrillary acidic protein (GFAP) in the forebrain and cerebellum of the mutant spastic rat

The spastic rat is a neurological mutant of the Han-Wistar strain with prominent spasticity, tremor, and ataxia. Neurodegeneration is found in the CA3 sector of the hippocampus and in Purkinje cells of the cerebellum. We examined the forebrain and cerebellum of spastic rats for glial reactions by using immunolabelling for the astrocytic marker, glial fibrillary acidic protein (GFAP). First, a map of the GFAP-distribution was made representing a systematic series of frontal sections in controls. Reactive astrocytes with increased GFAP should occur in the areas with established neuronal degeneration, but they could also demarcate further regions with pathology in this rat strain. Since the baseline levels of GFAP-immunoreactivity differ between brain regions, control rats and clinically normal littermates served as controls to judge relative increases in major structures. In the CA3 sector and hilus of the dorsal hippocampus, a massive gliosis was detected. In the cerebellum, a patchy increase of GFAP labelling in Bergmann glia was found. Further increases of GFAP-labelling in reactive astrocytes occurred in fiber tracts, the ventral thalamic nuclei, medial geniculate nuclei, pontine region and optic layer of the superior colliculus. Inconsistent changes were noted in cortex and pallidum. No defects of glial labelling or malformations in glial architectonics were found. The reactive changes of astroglial cells in hippocampus and cerebellum are in proportion to the neuronal degeneration. The glial reactions in the other brain regions possibly reflect a reaction to fiber degeneration and incipient neuronal degeneration or functional alterations of glial cells in response to neuronal dysfunction.     

Astroglial architecture of the carp (Cyprinus carpio) brain as revealed by immunohistochemical staining against glial fibrillary acidic protein (GFAP)

The present paper is the first comprehensive study on the astroglia of a teleost fish that is based on the immunohistochemical staining of GFAP (glial fibrillary acidic protein, an immunohistochemical marker of astroglia). The ray-finned fishes (Actinopterygii) and their largest group, the Teleostei, represent a separate pathway of vertebrate evolution. Their brain has a very complex macroscopic structure; several parts either have no equivalents in tetrapods or have a very different shape, e.g., the telencephalon. The results show that the teleost brain has a varied and highly specialized astroglial architecture. The primary system is made up of radial glia, which are of ependymal origin and cover the pial surface with endfeet. The tendency is, however, that the more caudal a brain area is, the less regular is the radial arrangement. A typical radial glia dominates some parts of the diencephalon (median eminence, lobus inferior and habenula) and the telencephalon. In the rest of the diencephalon and in the mesencephalon, the course of the glial fibers is modified by brain tracts. The most specialized areas of the teleost brain, the optic tectum and the cerebellum, display elaborate variations of the original radial system, which is adapted to their layered organization. In the cerebellum, an equivalent of the Bergmann-glia can be found, although its fiber arrangement shows meaningful differences from that of mammals or birds. In the lower brain stem radial glia are confined to fibers separating the brain tracts and forming the midline raphe. A dense ependymoglial plexus covers the inner surface of the tectum and the bottom of the rhombencephalic ventricle, intruding into the vagal and facial lobes. The structure and the position of the rhombencephalic plexus suggest that it corresponds to a circumventricular organ that entirely occupies the bottom of the ventricle. Perivascular glia show an unusual form as they consist of long fibers running along the blood vessels. In the large brain tracts long glial fibers run parallel with the course of the neural fibers. At least in the diencephalon, these glial fibers seem to be modified radial fibers. Real astrocytes (i.e., stellate-shaped cells) can be found only in the brain stem and even there only rarely. The glial specialization in the various areas of the teleost brain seems to be more elaborate than that found either in amphibia or in reptiles.     

Astroglial architecture of the carp ( Cyprinus carpio ) brain as revealed by immunohistochemical staining against glial fibrillary acidic protein (GFAP)

 The present paper is the first comprehensive study on the astroglia of a teleost fish that is based on the immunohistochemical staining of GFAP (glial fibrillary acidic protein, an immunohistochemical marker of astroglia). The ray-finned fishes (Actinopterygii) and their largest group, the Teleostei, represent a separate pathway of vertebrate evolution. Their brain has a very complex macroscopic structure; several parts either have no equivalents in tetrapods or have a very different shape, e.g., the telencephalon. The results show that the teleost brain has a varied and highly specialized astroglial architecture. The primary system is made up of radial glia, which are of ependymal origin and cover the pial surface with endfeet. The tendency is, however, that the more caudal a brain area is, the less regular is the radial arrangement. A typical radial glia dominates some parts of the diencephalon (median eminence, lobus inferior and habenula) and the telencephalon. In the rest of the diencephalon and in the mesencephalon, the course of the glial fibers is modified by brain tracts. The most specialized areas of the teleost brain, the optic tectum and the cerebellum, display elaborate variations of the original radial system, which is adapted to their layered organization. In the cerebellum, an equivalent of the Bergmann-glia can be found, although its fiber arrangement shows meaningful differences from that of mammals or birds. In the lower brain stem radial glia are confined to fibers separating the brain tracts and forming the midline raphe. A dense ependymoglial plexus covers the inner surface of the tectum and the bottom of the rhombencephalic ventricle, intruding into the vagal and facial lobes. The structure and the position of the rhombencephalic plexus suggest that it corresponds to a circumventricular organ that entirely occupies the bottom of the ventricle. Perivascular glia show an unusual form as they consist of long fibers running along the blood vessels. In the large brain tracts long glial fibers run parallel with the course of the neural fibers. At least in the diencephalon, these glial fibers seem to be modified radial fibers. Real astrocytes (i.e., stellate-shaped cells) can be found only in the brain stem and even there only rarely. The glial specialization in the various areas of the teleost brain seems to be more elaborate than that found either in amphibia or in reptiles. Accepted: 15 May 1998     

Glial fibrillary acidic protein and vimentin immunoreactivity of astroglial cells in the central nervous system of adult Podarcis sicula (Squamata, Lacertidae)

The present immunoperoxidase cytochemical study describes the distribution of glial intermediate filament molecular markers, glial fibrillary acidic protein (GFAP) and vimentin, in the brain and spinal cord of the adult lizard, Podarcis sicula . GFAP immunoreactivity is abundant and the positive structures are mainly represented by fibres of different lengths which are arranged in a rather regular radial pattern throughout the CNS. They emerge from generally immunopositive radial ependymoglia and are directed from the ventricular wall towards the meningeal surface. The glial fibres give origin to endfeet which are apposed to the blood vessel walls and subpial surface where they form the continous perivascular and subpial glia envelopes, respectively. In the optic tectum and spinal cord, star-shaped astrocytes coexist with radial glia. In the spinal cord, cell bodies of immunopositive radial glia are displaced from the ependyma. While vimentin immunoreactive elements are almost completely absent in the brain except for a few diencephalic radial fibres, the spinal cord ependyma exhibits a clearly vimentin positivity and no GFAP staining. In the Podarcis CNS the immunocytochemical response of the astroglial intermediate filaments appears typical of mature astroglia cell lineage since it fundamentally expresses GFAP immunoreactivity. Moreover, this immunocytochemical study shows that the Podarcis fibre pattern with predominant radial glial cells is morphologically more immature than in avians and mammalians, a condition suggesting that reptiles represent a fundamental step in the phylogenetic evolution of vertebrate astroglial cells.     

Importance of immunohistochemistry for neuro-oncology. II. Localization of factor VIII-associated proteins and glial fibrillary acidic protein (GFAP) in angiomatous and sarcomatous tumors

Immunhistochemical methods utilizing specific antibodies against Factor VIII-related antigen and glial fibrillary acidic protein were employed in studies of 48 intracranial and intraspinal tumors. Factor VIII-related antigen occurred only in endothelial cells of the vascular wall and is therefore not of importance for the differential diagnosis of CNS tumors. Isolated Factor VIII positive cells in the stroma of hemangioblastomas turned out to be mast cells which may also normally contain this substance. The GFAP positive cells in hemangioblastomas are believed to all be of astrocytic lineage. Many of the multinuclear giant cells present in monstrocellular sarcomas contained GFAP but were Factor VIII negative. Genuine fibroxanthoma of the meninges can apparently exist next to pleomorphic xanthoastrocytomas. As demonstrated by one of our cases, the demonstration of GFAP alone can successfully distinguish between them.     

The glial architecture of the median eminence of the Mongolian gerbil (Meriones unguiculatus); a study of glial fibrillary acidic protein (GFAP) immunoreactivity in semithin sections.

The glial architecture of the median eminence (ME) of the Mongolian gerbil (Meriones unguiculatus) was studied immunohistochemically. For this purpose, semithin sections of the proximal ME were processed according to the PAP technique using antibodies directed against glial fibrillary acidic protein (GFAP). Various glial cells were stained. Their distribution, the arrangement and morphology of their processes, and the spatial relations with adjacent tissue components could be examined in detail. Most of the immunoreactive cells were identified as either tanycytes (present throughout the internal zone, but preferentially located in the ependymal and subependymal layer), or as tanycyte-like cells (present throughout the external zone, but preferentially situated in the reticular layer). The processes of both cell types established numerous contacts with capillaries of the primary portal plexus in the external zone. Moreover, many projections of tanycyte processes to capillaries of the internal zone were revealed, most notably in the subependymal layer. Peculiar uni- and bipolar cells could be detected in the fibre layer of the internal zone, the processes of which were oriented parallel to the course of the axons of the hypothalamo-neurohypophyseal system. It was demonstrated that the methodology used to study the glial cells of the ME was also well applicable to the neural lobe. This technique, therefore, provides a valuable tool for the precise visualization of the majority of glial cells in the whole neurohypophysis of the gerbil. Thus, by sequential immunostaining of serial semithin sections investigations concerning the presence of multiple substances within single neurohypophyseal glial cells become possible.     

黄芩苷对惊厥持续状态幼年大鼠海马GFAP和NF-κB表达的影响

目的:观察幼年大鼠惊厥持续状态(status convulsion,SC)后脑组织海马中胶质细胞原纤维酸性蛋白(glial fibrillary acidic protein,GFAP)、核因子κB(NF-κB)的表达及神经细胞凋亡的变化,并探讨黄芩苷(baicalin,BC)对三者的影响。方法:将195只19日龄SD雄性大鼠随机分成生理盐水对照组(NS组)、惊厥持续状态组(SC组)和黄芩苷预处理组(BC组)3组;各组再按处死时点不同随机分为4 h、12 h、24 h、48 h和72 h亚组。采用氯化锂-匹鲁卡品化学点燃法制备幼年大鼠SC模型;应用免疫组化法检测大鼠海马中GFAP和NF-κB蛋白的表达情况,RT-PCR法检测GFAP的mRNA表达,TUNEL法检测神经细胞凋亡数的变化。结果:(1)免疫组织化学法检测显示SC组幼年大鼠海马中GFAP表达增强,与NS组比较差异有统计学意义(P0.05);与SC组比较,BC组的GFAP表达明显降低,差异有统计学意义(P0.05);SC组幼年大鼠海马中NF-κB表达增强,与NS组比较差异显著(P0.05);与SC组比较,BC组的NF-κB表达明显降低(P0.05)。(2)RT-PCR检测结果显示GFAP的mRNA表达趋势与蛋白基本相似。(3)SC组在惊厥后12 h海马CA1区TUNEL阳性细胞数已显著高于NS组(P0.01),48 h达峰值,而BC组TUNEL阳性细胞数在12 h~48 h均较SC组显著下降(P0.05或P0.01),但仍高于NS组(P0.05)。结论:SC后大鼠海马GFAP和NF-κB的表达增强。黄芩苷可下调匹鲁卡品致痫大鼠海马GFAP和NF-κB的表达,并使神经细胞凋亡数减少,提示黄芩苷在SC引起的脑损伤时对大鼠有保护作用。     

CTGF siRNA联合电针治疗对大鼠损伤脊髓星形胶质细胞GFAP表达的影响

目的:探讨抗CTGF小干扰RNA(small interferon RNA,siRNA)局部注射联合电针治疗对脊髓损伤(spinal cord injury,SCI)后胶质纤维酸性蛋白(GFAP)表达的影响。方法:将SD大鼠随机分为SCI组、CTGF siR-NA干扰(CTGF)组、CTGF siRNA干扰联合电针(EA+CTGF)组。制作大鼠SCI模型,将含有CTGF siRNA/Invivo-fectamine复合物溶液的明胶海绵移植入CTGF组和EA+CTGF组大鼠的脊髓(T10)损伤断端,SCI组用Invivo-fectamine转染试剂代替。EA+CTGF组在模型制备后每天的固定时间给予电针治疗。各组在3 d、7 d、14 d后分别取材,应用免疫荧光组织化学、Western Blot和逆转录聚合酶链反应(RT-PCR)观察星形胶质细胞的形态、数量和GFAP、GFAP mRNA表达变化。结果:SCI组星形胶质细胞反应性增生、胞体肥大,损伤边缘区形成GFAP强表达的胶质界膜;CTGF siRNA干预后,GFAP表达减弱,胞体减小,GFAP阳性细胞数减少;EA+CTGF组GFAP免疫反应表达明显降低,损伤边缘区GFAP荧光强度与脊髓其它区域基本相同。Western Blot结果显示:与SCI组相比,CTGF组与EA+CTGF组的GFAP均减少,有统计学意义(P<0.05),与CTGF组相比,EA+CTGF组的GFAP减少,有统计学意义(P<0.05);RT-PCR电泳结果表明损伤早期EA+CTGF组GFAP mRNA表达明显低于损伤组并有显著性差异(P<0.01),变化与Western Blot结果是一致的。结论:SCI后,CTGF siRNA联合电针治疗能有效阻止GFAP表达,使胶质反应减轻,有助于神经功能恢复。     

Immunocytochemical distribution of glial fibrillary acidic protein in the central nervous system of the Japanese quail (Coturnix coturnix japonica)

Summary In the present study we detailed the distribution of GFAP-immunopositive structures within the central nervous system of the Japanese quail. Different fixation and embedding procedures were applied. The best results were obtained on frozen cryostatic sections from freshly dissected brains subsequently fixed by a short immersion in cold acetone. Immunopositive structures were observed both with immunofluorescence, and with immunoperoxidase methods. Immunoreactive cell bodies and processes were observed within the whole central nervous system, and different cell types can be identified on the basis of their topographical location and morphology. A first class of astrocytes is composed of intensely stained unipolar cells lining the inner surface of the pia mater and the large blood vessels. A second type is represented by multipolar astrocytes of variable size, provided with an irregular cell body. The last type is represented by similar elements, showing an immunonegative cell body, that can be identified only by the presence of converging processes. These three types of cells, and several isolated processes, show a differential distribution within the quail central nervous system, both in the grey and in the white matter. Present results suggest that GFAP may represent a good marker for at least part of the astroglial population in quail.