Ultrastructural study of the embryonic development in the rat pineal gland

The ultrastructure of the albino rat embryo pineal gland was studied from day 13 of development through birth. In the first stages (13–16.5 days of development) the pineal evagination presents a barely differentiated epithelium. From 17 days onward the transformation of the pineal gland from a tubular evagination into a compact organ occurs. The obliteration of the recess takes place by means of two mechanisms: (a) multiple foldings of the epithelium which determine an approximation and fusion of the walls of the recess, and (b) occupation of the lumen by cells extruded from the pineal epithelium. Embryos of 18–21 days of gestation still show remains of the pineal recess. Frm day 16.5 onward elements of the pineal parenchyma have been found outside the pineal epithelium contour. They contact with the mesenchymal cells without a basal lamina separating both elements. Day 20 marks the beginning of recognizable differentiation of pineal cellular types. However, in the newborn rat these types are not yet clearly established.     

Selective accumulation of CCR5+ T lymphocytes into inflamed joints of rheumatoid arthritis

Chemokines and their receptors play critical roles in the selectiverecruitment of various subsets of leukocytes. Recent studieshave indicated that some chemokine receptors are differentiallyexpressed on T_h1 and T_h2 cells. However, available data concerningthe presence of T cells with a T_h1 or a T_h2 character and theexpression of chemokine receptors on infiltrating T cells inthe rheumatic joint are still limited. In this study, we investigatedthe expression of CC chemokine receptor 4 (CCR4) and CCR5, whichhave been shown to be preferentially expressed on T_h2 and T_h1respectively on T cells from rheumatoid arthritis (RA) patients.Although both CCR5⁺ and CCR4⁺ CD4⁺ T cell populations were observedin peripheral blood mononuclear cells from healthy controlsand osteoarthritis patients, these cell populations were decreasedin patients with active RA. In contrast, the vast majority ofsynovial fluid (SF) T cells from active RA patients expressedCCR5 but not CCR4. CCR5 ligands, MIP-1 and RANTES, were foundin RA SF at high levels. CCR5⁺ CD4⁺ T cells from SF mononuclearcells of RA patients produced IFN- but not IL-4 in responseto anti-CD3 stimulation in vitro. These results indicated thatdifferential expression of chemokine receptors plays a criticalrole for selective recruitment of pro-inflammatory T cells intothe joints of RA.     

Intensely negative-charged pericapillary spaces in the rat pineal gland

Electron microscopy of ultrathin sections stained with cationic iron colloid revealed that the rat pineal gland is provided with wide and intensely negative-charged pericapillary spaces. Light microscopically, the negative charging of the pericapillary spaces was completely eliminated by digestion with hyaluronidase and chondroitinase ABC. This pericapillary negative charging was also erased by digestion with collagenase. The results indicate that the negative charging is derived from sulfated proteoglycans which are bound to collagen molecules. These sulfated proteoglycans in the pericapillary spaces may retain numerous water molecules to form a tissue gel, and so act as a selective sieve regulating the passage of tissue molecules.     

Sympathetic neuroaxonal dystrophy in the aged rat pineal gland

Dysfunction of circadian melatonin production by the pineal gland in aged humans and rats is thought to reflect the functional loss of its sympathetic innervation. Our ultrastructural neuropathologic studies of the sympathetic innervation of the pineal gland of aged (24 months old) Fischer-344 and Sprague-Dawley rats showed loss of nerve terminals as well as the development of neuroaxonal dystrophy (NAD), an ultrastructurally distinctive distal axonopathy, far in excess of that in young control rats. Immunolocalization of tyrosine hydroxylase confirmed the age-related loss of normal noradrenergic innervation and development of NAD. NAD was more frequent in aged female rats compared to males and was particularly severe in aged female Sprague-Dawley rats compared to Fischer-344 rats. Pineal NGF content was significantly increased or unchanged in female and male aged Fischer-344 rats, respectively, compared to young controls. The rat pineal is a sensitive experimental model for the quantitative ultrastructural examination of age-related neuropathological changes in nerve terminals of postganglionic noradrenergic sympathetic axons, changes which may reflect similar changes in the diffusely distributed sympathetic innervation of other targeted endorgans.     

Presence of glial cells in the rat pineal gland: a light and electron microscopic immunohistochemical study

Immunoperoxidase methods for the demonstration of three glial antigens, vimentin, glial fibrillary acidic protein, and S-100 protein, were applied to routine-fixed paraffin sections of rat pineal gland. A pre-embedding electron microscope immunoperoxidase method was also used to study the ultrastructural localization of S-100 protein in pineal cells. Light and electron microscopic results showed the presence of these antigenic glial markers in the second pineal cell type. The term glial cell is proposed for the second of parenchymatous cell in rat pineal gland.     

阿尔茨海默病患者松果体MRI研究

目的　观察阿尔茨海默病（Alzheimer’s disease,AD)发病进程中松果体的MRI形态学改变。 方法　依据AD发病进程,分别采集NC组24例、MCI组18例、轻度AD组16例、中-重度AD组20例受试者大脑MRI扫描图像,测量松果体矢径、横径、高、体积,并分析组间各测量值变化趋势。 结果　松果体标化高MCI期、轻度AD期较NC组增大（P＜0.05）,中-重度AD期标化高较MCI期、轻度AD缩小（P＜0.05）;松果体标化矢径、标化横径、标化体积MCI期、轻度AD、中-重度AD与NC组比无明显变化（P＞0.05）,但中-重度AD较MCI期组缩小（P＜0.05）。 结论　在AD发病进程中松果体高先增大再萎缩,松果体高对MCI期、轻度AD患者的诊断有较大价值。     

Potassium currents in dissociated cells of the rat pineal gland

The properties of K currents of pineal cells were studied using the whole-cell variant of the patch-clamp technique. The total K current could be separated in two distinct components: a fast, transient current (I _t) and a slow current (I _s). The activation threshold ofI _t was at –35 to –30 mV. On depolarization to +50 mV it reaches a peak in 2–3 ms and inactivates almost completely in 50 ms. Half steady state inactivation occurs at –45 mV. Inactivation ofI _t is voltage-dependent and is well fitted by single exponentials with time constants between 17.2 ms at +50 mV and 27.2 ms at –10 mV. Inactivation is removed with time and the recovery period shortened by membrane hyperpolarization. The slow K current has a threshold at –20 to –15 mV. It reaches a maximum in about 30–40 ms and inactivates slightly, to about 80% of the peak value at the end of pulses lasting 200 ms. With 80 mM external K, tail currents recorded after short (1–2 ms) depolarizations were about 2.5 times faster than the tails recorded at the end of 50 ms pulses. The fast tails were removed by depolarizing prepulses but the slow tails remained unaltered. Thus, the fast and slow tails are probably a reflection of the closing of the transient and slow K channels. The transient K current of pineal cells has general characteristics similar to transient currents recorded in non-secretory cells, but also has particular kinetic properties.     

Hypothalamus-pituitary-thyroid axis interactions with pineal gland in the rat.

We examined in the rat several possible relationships between the pineal gland and the hypothalamus-pituitary-thyroid axis. The pineal gland, the retina, and the hypothalamus exhibited a diurnal rhythm in thyrotropin-releasing hormone (TRH) content with peak values occurring around 1200 h. This rhythm in the hypothalamus was abolished by constant light but was not affected by pinealectomy. Nor did pinealectomy affect hypothalamic TRH content, pituitary content of thyroid-stimulating hormone (TSH) or prolactin; serum levels of (TSH), triiodothyronine (T3), or thyroxine (T4), or serum free-thyroxine index; or free-triiodothyronine index. Melatonin did not affect TSH or prolactin release from the anterior pituitary or TRH release from the hypothalamus in vitro. Isoproterenol did not affect the TRH content of pineal glands in vitro; nor did TRH or T3 affect basal or stimulated activities of serotonin N-acetyltransferase, the presumed controlling enzyme in melatonin production. We found no evidence for significant interactions between the pineal gland and the hypothalamus-pituitary-thyroid axis.     

雌激素受体β在大鼠下颌下腺的免疫组织化学定位

目的：探讨雌激素β型受体（estrogen receptorβ，ER-β）在大鼠下颌下腺的定位和分布，为进一步研究ER-β在下颌下腺的可能功能提供形态学依据。方法：免疫组织化学SABC法。结果：大鼠下颌下腺浆液性腺细胞、泡心细胞、闰管、颗粒曲管及大于颗粒曲管的各级导管上皮细胞均呈ER-β免疫反应阳性，阳性反应物质主要位于阳性细胞胞质内，核呈阴性反应。结论：大鼠下颌下腺存在ER-β，雌激素可能通过ER-β的介导对下颌下腺功能进行调控。     

The blood vascular architecture of the rat pineal gland: a scanning electron microscopic study of corrosion casts

The blood vascular bed of the rat pineal gland was reproduced through a low viscosity methacrylate casting medium and observed with a scanning electron microscope. The pineal gland was located in front of the confluens sinuum which was formed by the confluence of the left and right transverse sinuses and the superior sagittal and great cerebral veins. The pineal gland was found to contain a rich vascular network of freely anastomosing capillaries. This network received a few afferent arteries from the posterior cerebral arteries while emitting ten to fifteen efferent veins. Most of these efferent veins drained into the upper segment of the great cerebral vein; the remaining one or two efferent veins continued directly into the confluens sinuum. A marked constriction, probably representing a venous valve or valve-like projection, was observed in the opening area of the great cerebral vein. Circular constrictions, probably representing sphincters, were imprinted in the efferent vessels. No direct vascular connection was noted between the pineal gland and the nervous tissues or between the pineal gland and the choroid plexuses of the third and lateral ventricles.     

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.     

Single unit recordings in the rat pineal gland: Evidence for habenulo-pineal neural connections

Summary Extracellular potentials were recorded in the pineal gland of urethane-anesthetized rats. Two distinct populations of excitable pineal cells were found, the silent cells which were driven by habenula stimulation and the spontaneously active cells. In the former case 17 of the responses (median latency of 1.2 ms) showed a positive-negative potential, and 6 (about 1 ms latency) showed only positive potential of 1–2 ms duration. The remaining cells (114), which could not be driven by habenula stimulation, exhibited spontaneous activity with a firing frequency from less than 1 Hz to greater than 100 Hz with a median firing frequency of 10 Hz.These experiments clearly demonstrate a direct habenulo-pineal fiber pathway and furthermore show that there are neuronal elements in the pineal which are only activated by habenula stimulation.