Ultrastructure of the pineal body of the common vampire bat,Desmodus rotundus

The type AB pineal body of the common vampire bat, Desmodus rotundus was recessed and lobulated, was extensively vascularized and intimately related to great veins, and was unassociated with the epithalamic region. The habenular and the posterior commmissures coursed anteriorly and were unassociated with the pineal. The saccular suprapineal recess of the third ventricle extended dorsally juxtaposed to the pineal body. These anatomical features are likely to make pinealectomies in the vampire more difficult to manage. The pineal parenchyma consisted of light pinealocytes surrounded by canaliculi of various sizes, often transmitting unmyelinated nerve fibers and glial processes. Desmosomes were common. The pinealocyte nuclei were large and highly infolded; characteristic cytoplasmic constituents included abundant dilated Golgi complexes associated with clear vesicles, numerous polyribosomes, few single cisternae of ribosome-studded rough endoplasmic reticulum, mitochondria, and occasional multivesicular bodies and lysosomes. Almost all pinealocytes exhibited centrioles and some, in addition, displayed basal bodies but rarely ciliary shafts. A conspicuous feature of the pinealocyte cytoplasm was the presence of branched bundles of intermediate filaments, especially in the perinuclear zone. Siderotic macrophages, lipofuscin-pigment-containing phagocytic cells, mast cells, myelin bodies, and both fenestrated and continuous capillaries were present. The perivascular compartment was densely packed with unmyelinated nerve bundles containing small to large fibers exhibiting axoaxonic densities. Other constituents of the perivascular compartment were club-shaped pinealocyte processes filled with clear vesicles, microtubules, an occasional mitochondrion, glial processes, and collagen fibers. “Synapselike” contacts were observed between the axons and pinealocyte processes. Abundant pinocytotic vesicles in the capillary endothelium indicated active pinocytosis. Myelinated nerve fibers were lacking. The pineal ultrastructure of Desmodus is in part unlike that reported for other mammals, including bats.     

The fine structure of the hamster pineal gland

The pineal gland of the hamster has been examined with the electron microscope. The gland is composed of two types of parenchymal cells, a “light” and a “dark” cell. Blood vessels are infrequently encountered and display little perivascular space. Axons, nerve endings, pineal cell processes, and occasional glial processes ramify within the parenchyma of the gland. The parenchymal cells display abundant mitochondria, many with a tubular internum. Smooth and rough surfaced endoplasmic reticulum, a Golgi apparatus and lipid droplets are regular features of both cell types. Vesicles of varying size and containing electron dense centers are present in the cell body. Parenchymal cells branch extensively and are characterized by the presence of microtubules in addition to the usual organelles encountered in the cell body. Pineal cell process terminations regularly show accumulations of vesicles with electron dense granulations.     

Ultrastructural evidence for seasonal changes in pinealocytes of the 13-lined ground squirrel,spermophilus tridecemlineatus: A qualitative and quantitative study

The fine structure of pinealocytes in the hibernating ground squirrel, Spermophilus tridecemlineatus, was found to vary both qualitatively and quantitatively according to the season in which the animals were sacrificed. Ultrastructural features of pinealocytes from fall (prehibernation) and winter (hibernation) periods, when the animals were sexually quiescent, included: (1) arrangement of the endoplasmic reticulum into flattened stacks or concentric rings (formations which have been implicated in antigonadotropic activity of the pineal); (2) condensations of a fine granular material; and (3) dilation of the cisternae of the endoplasmic reticulum and Golgi bodies with an increased number of Golgi associated vesicles. Moreover, there was an apparent increase in the number of dense-cored vesicles and microtubules in pinealocytes of winter animals. These findings indicate that a circannual rhythm in pinealocyte ultrastructure occurs in this species and further suggest that cellular activity is seasonal.     

Ultrastructure of palatal taste buds in the perihatching chick

Palatal taste buds of perihatching chicks were examined by electron microscopy. Four intragemmal cell types were characterized. (1) Light: with voluminous, electron-lucent cytoplasm containing scattered free ribosomes, rough and smooth endoplasmic reticulum, plump mitochondria, sparse perinuclear filaments, occasional Golgi bodies, and numerous clear and dense-cored vesicles. Clear vesicles sometimes aggregate in a presynaptic-like configuration apposed to an axonal profile. These cells contained large, spherical, uniformly granular nuclei with one nucleolus. (2) Dark: with dense cytoplasm containing filamentous bundles surrounding the nucleus, occasional clear vesicles, centrioles, rough endoplasmic reticulum, and compact mitochrondria. The apical cytoplasm noticeably lacks dense secretory granules. Irregular to lobulated nuclei are densely granular, and contain scattered clumps of chromatin, adhering especially to the inner leaflet of the nuclear membrane, and at least one nucleolus. Cytoplasmic extensions of dark cells envelop other intragemmal cell types and nerve fibers. Light and dark cells project microvilli into the taste pore. (3) Intermediate: contain gradations of features of light and dark cells. (4) Basal: darker than the other intragemmal cell types and confined to the ventral bud region. Putative afferent synapses in relation to light cells, and axo-axonal contacts are described. While the appearance of axo-axonal contacts may be a transient developmental event, other bud features are consonant with observations in adult chickens and suggest that the peripheral gustatory apparatus is mature at hatching in this precocial avian species.     

成年牦牛松果体的光镜和电镜观察

目的 探讨成年牦牛松果体形态结构特征,为哺乳动物松果体形态结构研究积累资料.方法 光镜HE染色、浸银染色和透射电子显微镜技术.结果 光镜下,牦牛松果体由松果体细胞、少量的神经胶质细胞、毛细血管和神经等组成.电镜下,松果体细胞电子致密度低,细胞质内含丰富的线粒体、粗面内质网、滑面内质网、微管、微丝和核糖体;高尔基复合体数量极少,典型异质细胞器突触带呈球形,多位于质膜附近.神经胶质细胞的细胞质内含丰富的线粒体,其胞体突起呈球形膨大伸入到松果体细胞之间.松果体细胞以及神经胶质细胞间均存在突触和连接复合体.牦牛松果体内毛细血管为连续型,其远腹侧血管周围可见色素细胞.结论 成年牦牛松果体细胞内存在神经上皮样和腺上皮样2种细胞连接方式.毛细血管为连续型.松果体细胞内细胞器发达,但很少观察到高尔基复合体.     

Structure of taste buds in foliate papillae of the rhesus monkey,Macaca mulatta

Taste buds in foliate papillae of the rhesus monkey were examined by electron microscopy. Three distinct cell types were identified. Type I cells were narrow elongated cells containing an oval nucleus, bundles of intermediate filaments, several Golgi bodies, and characteristic apical membrane-bounded dense granules. These cells exhibited morphological variations: some had a moderately dense cytoplasm, perinuclear free ribosomes, and flattened sacs of rough endoplasmic reticulum; others had a more lucent cytoplasm, dilated irregular rough endoplasmic reticulum, lysosome-like dense bodies, and lipid droplets. Type II cells typically contained a spherical, pale nucleus, a prominent nucleolus, supranuclear and infranuclear Golgi bodies, mitochondria with tubular cristae, and one or two centrioles. This cell type, too, showed some variation in the relative amounts of ribosomes and smooth endoplasmic reticulum, which varied inversely with each other. Type III cells were characterized by a clear apical cytoplasm essentially devoid of ribosomes and containing microtubules. In a few type III cells, the peri- and infranuclear regions contained many ribosomes and some rough endoplasmic reticulum. In most Type III cells, there were large numbers of dense and clear vesicles in the peri- and infranuclear regions; some of the vesicles were grouped in synapse-like arrangements with adjacent nerves. The morphological variations exhibited by all three cell types could be accounted for by age differences in each of the cells. This would be consistent with the notion that cell renewal occurs in each of the three cell populations.     

Ultrastructure of the pineal gland of the monkey, Macaca fascicularis, with special reference to the presence of synaptic junctions on pinealocytes

Summary The present study described the normal ultrastructure of the monkey pineal gland. The gland was composed of the principal pinealocytes, intramural neurons and glial cells. The nucleus of the pinealocytes was deeply infolded with evenly distributed chromatin materials. The abundant cytoplasm was rich in organelles including the well-developed Golgi apparatuses, multivesicular bodies, dense-cored vesicles and widely scattered free and polyribosomes. A variety of axon terminals was observed and the majority of them contained pleomorphic agranular vesicles with a few large dense-cored vesicles. A few terminals showed flattened vesicles or small dense cored vesicles. Some of the axon terminals formed synaptic contacts with the cell bodies of pinealocytes. These synapses were mainly concentrated in the posterior third of the gland. The occasional intramural neurons observed were postsynaptic to axon terminals containing round agranular vesicles. The sources of the nerve fibres and terminals forming synaptic junctions with pinealocytes and intramural neurons were discussed.     

大鼠松果体衰老的形态学研究

目的 探讨松果体形态结构的衰老性变化,为进一步研究松果体与衰老的关系提供形态学基础。方法 随机选取3月龄和34月龄SD大鼠10只分别作为青年组和老年组,用光镜和电镜结合形态计量学分法分析松果体细胞和神经胶质细胞密度及其指数;松果体细胞线粒体的Vv、Sv、Nv,高尔基器的Vv、Sv、粗面内质网的Sv、溶酶体的Vv;松果体神经终末的Vv及其线粒体的Vv、Sv、Nv、小颗粒囊泡的NA。结果 与青年组相比,老年组松果体细胞核形状不规则,核膜皱褶增多和加深。细胞浆内粗面内质网减少,排列紊乱,分散,脱颗粒明显;线粒体结构不清、肿胀、嵴断裂、消失、空泡化等。老年组松果体细胞密度比青年组减少,而神经胶质细胞密度增加,差异有高度显著性(P<0.01)。老年组神经胶质细胞指数比青年组高(P<0.01)。老年线粒体Vv与青年组无差别,但老年组线粒体Sv、Nv均比青年组减少(P<0.01)。老年组高尔基器的Vv、Sv均比青年组减少(P<0.01);老年组粗面内质网Sv比青年组减少,而老年组溶酶体Vv比青年组增加(P<0.01);老年组神经终末Vv比青年组减少(P<0.01);老年组神经终末中小颗粒囊泡NA比青年组减少(P<0.01);老年组线粒体Sv、Nv比青年组减少(P<0.05),两组神经终末中线粒体Vv无差别(P>0.05)。结论 老年大鼠松果体已发生衰老性变化,这可能与机?     

Effect of photoperiod on pineal gland volume and pinealocyte size in the chinese hamster,Cricetulus griseus

Male adult (200-day-old) Chinese hamsters (Cricetulus griseus) raised from weaning under either LD 16:8 or LD 8:16 were used. The pineal gland of the Chinese hamster consists of superficial (major) and deep (minor) components and a continuous, or interrupted, narrow parenchymal stalk interposed between them. The volume of the superficial pineal including the parenchymal stalk is greater under LD 16:8 than under LD 8:16. Under both photoperiods, pinealocytes in the superficial pineal have larger nuclei and more abundant cytoplasm than those in the deep pineal. Nuclei in the superficial pineal appear pale and usually have irregular profiles, whereas those in the deep pineal appear dark and have round profiles. In the superficial pineal, pinealocyte nuclei are larger, paler, and more irregular; and, in addition, nuclear density is lower under LD 16:8 than under LD 8:16. Similar, but less prominent, photoperiod-induced changes occur in the volume of the deep pineal, the size of pinealocytes, and pinealocyte nuclear morphology in the deep pineal. The results indicate that the development and differentiation of pinealocytes in both pineal portions may be advanced under long photoperiods and delayed under short photoperiods, although pinealocytes in the deep pineal may remain not fully differentiated even in adults. Since testicular weights and body weights are similar under both photoperiods, the photoperiod may exert marked influences on the development of the pineal gland without affecting reproductive activity and growth rates of animals.     

扬子鳄松果腺的超微结构

目的;为不同种系松果腺超微结构的比较及有关方面的深入研究提供必要的形态学依据。方法：采用光、电镜观察。结果：扬子鳄松果腺已进化成实质性腺体,其实质主要由腺细胞构成,腺细胞体积较大,突起较多,核呈圆形、卵圆形、或不规则形,异染色质较少且靠近核膜。低电子密度的胞浆内含有丰富的高尔基复合体、粗面内质网及滑面内质网。清亮小泡及线粒体亦较多见,偶见脂滴、溶酶体、中心粒、微管、微丝及膜层样结构。间质内毛细血管较丰富,偶见神经胶质细胞。结论：两栖爬行类动物──扬子鳄确有松果腺存在,其松果腺已进化成实质性腺体。     

A light and electron microscopic study of the pineal gland of the ground squirrel,Citellus tridecemlineatus

The pineal gland of the 13-lined ground squirrel (Citellus tridecemlineatus) has been examined at the light and electron microscopic level. This gland is composed of low-density parenchymal cells interspersed among which are occasional glial, vascular and neural elements. Punctuating the glandular parenchymal mass are prominent perivascular and intercellular spaces. The parenchymal cells possess numerous mitochondria and less prominent profiles of rough and smooth-surfaced endoplasmic reticulum. Golgi apparatus, microtubules and lipid droplets of varying size and electron density constitute regular cytoplasmic features, with dense-core vesicles being present occasionally. The parenchymal cells have numerous processes. One among these in each cell extends for several micra to terminate in a bulbous expansion containing both clear and dense-core vesicles and occasional electron-dense inclusions. These bulbous terminals are found within the perivascular and intercellular spaces where they course in close proximity to both other parenchymal elements and axon terminals. Glial cells and their processes invest the pineal periphery and incompletely separate the parenchymal cells.     

Ultrastructural studies on postnatal differentiation of neurons in the substantia gelatinosa of rat cervical spinal cord

Neuroblasts of the substantia gelatinosa at birth were small with large oval nuclei and scanty cytoplasm. The cytoplasm possessed ribosomes and mitochondria. Granular endoplasmic reticulum and Golgi complexes were generally absent or rudimentary. Electron dense bodies were seldom observed. By the end of the first week, the nuclei of several cells demonstrated early nuclear invaginations; cytoplasm exhibited growth cones, a well developed granular endoplasmic reticulum and Golgi complexes. At several points the channels of endoplasmic reticulum became continuous with the perinuclear space. By the end of the second week, differentiation of the neuroblasts was more advanced. More nuclei showed invagination of their contour. The cytoplasm revealed well developed granular endoplasmic reticulum and multiple Golgi complexes. Numerous vesicles and dense bodies were found adjacent to the Golgi complexes. Arrays of agranular endoplasmic reticulum also appeared late in the second week. By the third week, features of neuronal differentiation, such as nuclear invaginations, granular endoplasmic reticulum, agranular membrane configurations, multiple Golgi complexes and dense bodies in the cytoplasm became well established.     

Ultrastructural studies on postnatal differentiation of neurons in the substantia gelatinosa of rat cervical spinal cord.

Neuroblasts of the substantia gelatinosa at birth were small with large oval nuclei and scanty cytoplasm. The cytoplasm possessed ribosomes and mitochondria. Granular endoplasmic reticulum and Golgi complexes were generally absent or rudimentary. Electron dense bodies were seldom observed. By the end of the first week, the nuclei of several cells demonstrated early nuclear invaginations; cytoplasm exhibited growth cones, a well developed granular endoplasmic reticulum and Golgi complexes. At several points the channels of endoplasmic reticulum became continuous with the perinuclear space. By the end of the second week, differentiation of the neuroblasts was more advanced. More nuclei showed invagination of their contour. The cytoplasm revealed well dev-loped granular endoplasmic reticulum and multiple Golgi complexes. Numerous vesicles and dense bodies were found adjacent to the Golgi complexes. Arrays of agranular endoplasmic reticulum also appeared late in the second week. By the third week, features of neuronal differentiation, such as nuclear invagination, granular endoplasmic reticulum agranular membrane configurations, multiple Golgi complexes and dense bodies in the cytoplasm became well established.     

Postnatal development of mitral cell perikaryon in the olfactory bulb of the rat. A light and ultrastructural study

The differentiation of the mitral cell perikaryon in postnatal rat olfactory bulb was studied with the light and electron microscope. At birth the mitral cell was distinguishable and occupied a definitive position in the mitral cell layer. The cell contained a large oval nucleus surrounded by a thin rim of cytoplasm. Ribosomes, free and clustered, were scattered in the cell cytoplasm. Rough endoplasmic reticulum was relatively scarce. The Golgi complexes were made up of stacks of smooth-surfaced cisternae and associated vesicles. In certain cases the Golgi complexes projected into cellular processes. Mitochondria were present in all regions of the cytoplasm and contained well developed cristae. At the end of the first week, the mitral cell had developed significantly in size, and the cytoplasm contained well-developed rough endoplasmic reticulum. The Golgi complexes were made up of several stacks of smooth-surfaced cisternae with the association of vesicles and electron dense bodies. The apical dendrites o mitral cells at this periiod had increased significantly in length. Subsequently, during the second and third week, the rough endoplasmic reticulum and Golgi complexes became well developed. Associated with the Golgi complexes were electron dense lysosomal bodies. At three weeks and in older cells it was observed that dense lysosomal bodies. At three weeks and in older cells it was observed that dense lipofuschin granules increased significantly. It is suggested that the mitral cell matures and differentiates earlier than cells in the cerebral cortex.     

The thyroid gland of the woodchuck,Marmota monax: A morphological study of seasonal variations in the follicular cells

The morphology of the thyroid gland of the woodchuck, Marmota monax, was studied during the four seasons of the year. In the spring the thyroid is extremely heterogeneous in appearance. Some follicular cells appear quite active. They contain a well defined Golgi apparatus, abundant large colloid droplets and pseudopodia but few, if any, apical vesicles. Other less active cells have poorly defined rough surfaced endoplasmic reticulum and lack a well developed Golgi apparatus. They do not contain apical vesicles or colloid droplets. Summer thyroids have uniformly small follicles which are lined by high cuboidal cells containing numerous mitochondria, apical vesicles, abundant rough surfaced endoplasmic reticulum, and lipid droplets but few colloid droplets. There is extensive lateral and basal infolding of the cytoplasmic membranes in these cells. In the fall and winter the follicles are larger than in the summer and contain more colloid. Numerous heterogeneous dense bodies appear in the cytoplasm of the follicular cells in the fall and increase in number in the winter when there is an obvious sparsity of such glycoprotein synthetic organelles as Golgi apparatus and rough surfaced endoplasmic reticulum. These morphologic changes are compared with previous studies of thyroid structure and function in other animals and are correlated with the seasonal physiologic activities of the woodchuck.     

Ultrastructural characterization of glial cells in the rat pineal gland with special reference to the pineal stalk

In the present study the “interstitial” cells of the superficial pineal gland and the nonparenchymal cells of the pineal stalk in Sprague-Dawley rats were examined ultrastructurally with the aim of defining the cells more closely. The “interstitial” cells of the superficial pineal gland do not represent a homogeneous cell population. The most abundant cell type is the mononuclear phagocyte, most easily recognized by its dark appearance and its content of primary and conspicuous secondary lysosomes. Astrocytes can be distinguished by the typical appearance of their nuclei (i.e., a thin continuous rim of heterochromatin adjacent to the nuclear membrane), identical to that of astrocytes in the CNS. Depending on the absence or presence of glial filaments and their amount, a spectrum of astrocytic cells is present. Mature astrocytes with filaments throughout their cytoplasm are rare. Immature glial cells with few or no filaments predominate. In the vicinity of blood vessels pericytes are present. In view of the fact that the “interstitial” cells could generally be identified it is suggested to abandon the term interstitial for the cells in question. In the pineal stalk mature astrocytes predominate; they have some features in common with pinealocytes, i.e., the presence of intergrade endoplasmic reticulum and grumose bodies (lysosomes). Other unusual features are a relative abundance of coated pits and vesicles. Oligodendrocytes are restricted to the proximal part of the stalk, near the deep pineal, where myelinated axons are abundant. More distally a few Schwann cells were seen.     

Quantitation of ultrastructural changes in the mouse pineal in response to continuous illumination

Adult male mice were exposed to either alternating illumination or constant illumination for 70 days. Light and dark pinealocytes were compared as to distribution within the gland and ultrastructure. Quantitative studies with the electron microscope revealed a significant reduction in pinealocyte size and Golgi complex size in constant light treatment, as well as a marked but non-significant reduction in the concentration of lipid droplets and irregular vacuoles. Under constant light treatment the cross-sectional area of pinealocyte pericapillary terminals and the number of granulated vesicles per terminal decreased significantly. A greater number of mitochondria appeared swollen, with rarified matrix and reduced numbers of cristae, with constant light treatment. These results provide ultrastructural correlation with the known reduction of pineal weight, protein synthesis and antigonadotrophic activity that is seen with constant light treatment. The marked decrease in concentration of pinealocyte granulated vesicles in constant light treatment gives morphological support to the theory that these vesicles contain antigonadotrophic secretory material.     

Quantitation of ultrastructural changes in the mouse pineal in response to continuous illumination.

Adult male mice were exposed to either alternating illumination or constant illumination for 70 days. Light and dark pinealocytes were compared as to distribution within the gland and ultrastructure. Quantitative studies with the electron microscope revealed a significant reduction in pinealocyte size and Golgi complex size in constant light treatment, as well as a marked but nonsignificant reduction in the concentration of lipid droplets and irregular vacuoles. Under constant light treatment the cross-sectional area of pinealocyte pericapillary terminals and the number of granulated vesicles per terminal decreased significantly. A greater number of mitochondria appeared swollen, with rarified matrix and reduced numbers of cristae, with constant light treatment. These results provide ultrastructural correlation with the known reduction of pineal weight, protein synthesis and antigonadotrophic activity that is seen with constant light treatment. The marked decrease in concentration of pinealocyte granulated vesicles in constant light treatment gives morphological support to the theory that these vesicles contain antigonadotrophic secretory material.     

Photosensory elements in the pineal gland of the Japanese quail, with special reference to the paraboloid

In 1-day-old Japanese quails, Coturnix coturnix japonica, photosensory elements of the pineal gland were examined by means of histochemical demonstration of glycogen and transmission electron microscopy. The parenchymal cells of the quail show immature structure, especially, small apical protrusion with a few mitochondria in the pinealocyte and rare appearance of the dense body in the supporting cell. The paraboloid is found in cytoplasmic processes projecting into the follicular lumen and in perikarya of the follicular cells. It is composed of a well-developed network of tubular smooth-surfaced endoplasmic reticulum and abundant glycogen granules, but there is not a higher concentration of glycogen in its central region. The paraboloid-containing cell is considered as a type of the pinealocyte, because of occasional appearance of the synaptic ribbon in its perikaryon. In addition to lamellar whorls, regular stacks of lamellar disks are observed in the pineal lumen, being adjoining to the paraboloid-containing cytoplasmic process. The present results may provide further evidence for the direct photoreception by the avian pineal.     

Fine structure of the adrenocortical homologue in the north American eel and modifications following seawater adaptation

The ultrastructure of the adrenocortical homologue (AH) of the north American eel (Anguilla rostrata) was studied from freshwater and long-term (1.5 years) seawater (SW) adpated animals. The AH tissue situated in the wall of cardinal veins is surrounded by a thin layer of collagenous capsule; in the region away from the vein wall, parenchymal cells are separated by interstitial lacunae containing collagen bundles, capillaries, chromaffin cells and nerve fibers often applied closely to the surface of AH cells. The free surface of the cell near the vein wall, capillaries or interstitial space extends numerous slender microplicae. The cytoplasm is characterized by the presence of mitochondria with tubular cristae, a network of smooth endoplasmic reticulum, a few cisternae of rough surfaced endoplasmic reticulum, well developed Golgi apparatus, coated vesicles, centrioles, cilium, filaments, microtubules, dense bodies of variable nature and a scarcity of liposomes. The cell nuclei possess invaginated cytoplasmic pseudo-inclusions. Electron histochemical reaction for free cholesterol revealed the occurrence of needle-shaped crystals mainly associated with surface microplicae and smooth endoplasmic reticulum, which seems to be the major organelle for storage or synthesis of this steroid precursor. SW animals indicated ultrastructural signs of stimulated steroid synthesis and secretion, i.e., high degree of pseudo-follicle formation, increased electron density of mitochondria, greater abundance of lysosomal dense bodies, hyperactivity of Golgi apparatus and dilation of smooth endoplasmic reticulum tubules. Some SW fishes showed extensive deposition of osmiophilic inclusions in the mitochondria and stacks of elongated cup-shaped mitochondria. Chronic seawater acclimation enhances AH activity as judged by ultrastructural criteria with ultimate mitochondrial degeneration resulting possibly from prolonged cortisol hypersecretion; the latter may be linked with physiologic re-adjustment of ionic transfer mechanism in hyperosmotic medium.