FSH分泌细胞在皖西白鹅脑垂体中的分布与定位

采用免疫组化SABC法并结合DAB显色技术时皖西白鹩脑垂体结构和促卵泡素(follicular stimulating hormone,FSH)分泌细胞进行了研究和定位.结果发现,皖西白鹅的垂体前叶由远侧部和结节部构成,没有中间部.垂体FSH免疫阳性细胞分布广泛,但前叶远侧部分布较多,从而表明皖西白鹅整个垂体都有FSH分泌,主要分泌部位在垂体前叶的远侧部.     

Orexin‐B‐like immunoreactivity in pituitary αMSH‐producing cells and median eminence GnRH‐containing fibres of the flat‐tailed house gecko

We examined the distribution of the orexin‐like peptides in the pituitary and median eminence of the flat‐tailed house gecko (Hemidactylus platyurus) using immunohistochemistry. Orexin‐B‐like, but not orexin‐A‐like, immunoreactivity was detected in the pituitary, specifically in the pars intermedia, and these cells corresponded to alpha‐melanocyte‐stimulating hormone (αMSH)‐producing cells. Orexin‐B and αMSH secreted from pars intermedia may modulate secretion of adenohypophyseal cells in the pars distalis. In the median eminence, orexin‐B‐immunoreactive puncta and fibres were observed, and these structures corresponded to gonadotropin‐releasing hormone (GnRH)‐immunoreactive puncta and fibres. Orexin‐B secreted from GnRH‐containing neurons in the hypothalamus may affect thyrotropin‐releasing hormone‐containing neurons resulting in modulation of αMSH secretion of melanotrophs in the pars intermedia.     

Naturally occurring lesions in some endocrine glands of laboratory maintained baboons (Papio sp.)

The pituitary gland was examined from 623 immature baboons (Papio cynocephalus and Papio anubis). Findings included microscopic cysts in the pars distalis (132), pars intermedia (two) and pars nervosa (one). In 641 necropsies five cases of unilateral thyroid glands were noted. Microscopic thyroid lesions included ectopic thymus (328), minor lymphocytic infiltrates (14) and cysts (two). Parathyroid lesions consisted of ectopic thymus (73) and cysts (24). Dilated capillaries in the islets of Langerhans was the only microscopic change seen in the endocrine pancreas. All lesions generally occurred in both untreated control and treated baboons at similar incidences. They were considered to be naturally occurring, a part of the "background" pathology of these endocrine glands in immature baboons.     

Expression of leukemia inhibitory factor and leukemia inhibitory factor receptor in the canine pituitary gland and corticotrope adenomas

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine of the IL-6 family that activates the hypothalamic-pituitary-adrenal axis and promotes corticotrope cell differentiation during development. The aim of this study was to investigate the expression of LIF and its receptor (LIFR) in the canine pituitary gland and in corticotrope adenomas, and to perform a mutation analysis of LIFR. Using immunohistochemistry, immunofluorescence, and quantitative expression analysis, LIF and LIFR expression were studied in pituitary glands of control dogs and in specimens of corticotrope adenoma tissue collected through hypophysectomy in dogs with pituitary-dependent hypercortisolism (PDH, Cushing's disease). Using sequence analysis, cDNA was screened for mutations in the LIFR. In the control pituitary tissues and corticotrope adenomas, there was a low magnitude of LIF expression. The LIFR, however, was highly expressed and co-localized with ACTH_1-24 expression. Cytoplasmatic immunoreactivity of LIFR was preserved in corticotrope adenomas and adjacent nontumorous cells of pars intermedia. No mutation was found on mutation analysis of the complete LIFR cDNA. Surprisingly, nuclear to perinuclear immunoreactivity for LIFR was present in nontumorous pituitary cells of the pars distalis in 10 of 12 tissue specimens from PDH dogs. These data show that LIFR is highly co-expressed with adrenocorticotropic hormone (ACTH) and α-melanocyte-stimulating hormone (α-MSH) in the canine pituitary gland and in corticotrope adenomas. Nuclear immunoreactivity for LIFR in nontumorous cells of the pars distalis may indicate the presence of a corticotrope adenoma.     

Comparative Cytology of the Neuro-Intermediate Lobe of the Reptilian Pituitary

In many reptiles the pars nervosa bears a striking resemblance to the mammalian median eminence. The structure of the ependymal cells lining the infundibular recess and the fact that many of them are in synaptic contact with nerve fibres suggests that they subserve more than a mere structural role and that they may be involed in secretory or transport functions forming functional units with neuronal elements of the hypothalamus. All species possess large numbers of typical peptidergic fibres although some have in addition a second, rarer type; aminergic fibres are also present but their numbers vary in different species. The pars intermedia contains nerve fibres only in snakes and Caiman but even in these species the innervation is sparse. This observation coupled with the organisation of the pars nervosa leads to the conclusion that the latter may act, in part at least, as the “median eminence” of the pars intermedia. A more extensive survey, particularly amongst the families of lizards thought to be related to the ancestors of snakes, might throw further light upon the course of evolution of control mechanisms within the pars intermedia of reptiles.     

Ultrastructure of the Neuro-and Adenohypophysis of the Teleost,Chasmichthys dolichognathus*

Ultrastructure of the Neuro-and Adenohypophysis of the Teleost, Chasmichithys dolichognathus The hypophysis of the gobiid teleost investigated is embedded in the hypothalamus except for its ventral surface. The neurohypophysis constitutes a thin sheet covering the adenohypophysis. The anterior part of the neurohypophysis, which wraps the rostral pars distalis and the most rostral part of the caudal pars distalis, contains neurosecretory axons the most predominant type of which is characterized by granulated vesicles between 70 and 120 nm. in diameter. In the posterior part of the neurohypophysis which covers the main part of the caudal pars distalis and the pars intermedia the most abundant neurosecretory axons contain granulated vesicles between 110 and 170 nm. in diameter. Following discussion of the regional structural differences, the goby neurohypophysis is compared with the median eminence and the posterior lobe of tetrapods.     

Evaluation of pituitary gland anatomy and histopathologic findings in clinically normal horses and horses and ponies with pituitary pars intermedia adenoma

OBJECTIVE: To determine size and weight of the pituitary gland and associations between pituitary gland size and weight and sex and age in horses without clinical signs associated with pituitary pars intermedia adenoma (PPIA) and horses and ponies with PPIA. ANIMALS: Pituitary glands from 100 horses without clinical signs of PPIA and 19 horses and 17 ponies with PPIA. PROCEDURES: Pituitary glands were weighed, measured, and examined histologically by use of H&E stain. Masson trichrome and periodic acid-Schiff staining were used, when appropriate. Histologic lesions in the pars intermedia, pars distalis, or both were classified as no significant lesions, single or multiple cysts, focal or multifocal hyperplasia, single or multiple microadenomas, and adenoma. Relative pituitary weight (RPW) was calculated as pituitary weight (grams) divided by body weight (grams). RESULTS: There was an age-related increase in the presence of pituitary lesions in the pars distalis and pars intermedia in geldings, mares overall, and non-pregnant mares. Mean (+/-SD) RPW in horses with PPIA was not significantly different from ponies with PPIA (15+/-5.9 x 10(-6) and 16+/-72 x 10(-6), respectively). Maximum pituitary weight in a horse with PPIA was 13.9 g (RPW, 2.9 X 10(-5)). Plasma glucose concentration was positively correlated with RPW in ponies with PPIA. CONCLUSIONS AND CLINICAL RELEVANCE: Pituitary lesions may be a factor in horses with insulin resistance and laminitis before development of clinical signs of PPIA. Ovarian steroids may be involved in the pathogenesis of lesions in the pars intermedia.     

The Effect of Season on the Histologic and Histomorphometric Appearance of the Equine Pituitary Gland

The objective of this study was to determine the effect of season on the histologic and histomorphometric appearance of the normal equine pituitary gland. Pituitary glands were collected at necropsy from 121 horses throughout the year. Plasma was also collected from 59 of these horses before euthanasia. Hematoxylin and eosin stained median sagittal sections of each pituitary were evaluated and histologically graded by three pathologists. Histomorphometric analysis was performed on the same slides. Plasma α-melanocyte stimulating hormone was measured by radioimmunoassay in a subset of horses (n = 59). A total of 118 pituitary glands were included in the study after exclusions were made on the basis of the presence of pars intermedia (PI) adenomas (>5 mm). There was a positive correlation between PI hormone concentration (α-melanocyte stimulating hormone) and PI area. Pituitary gland measurements and grades from samples collected in the fall were compared with those collected in the nonfall months using t-test. The PI area, total pituitary area, and PI/total pituitary ratio were significantly greater in the fall compared with nonfall months (P < .0001, P < .01, P < .0001, respectively). Pituitary grades were also higher in the fall compared with nonfall months (P < .001). There was no seasonal difference in pars distalis or pars nervosa area. The results of this study show that the normal equine pituitary shows seasonal changes in appearance and size. These changes must be considered when using postmortem histologic evaluations in the diagnosis of pituitary pars intermedia dysfunction or for validation of antemortem diagnostic tests.     

The hypophysis of Monodelphis domestica (Marsupialia): the state of organ development and cell differentiation in the adenohypophysis on different days post partum

In the newborn gray short-tailed opossum, Monodelphis domestica, the fusion of the neurohypophysis and adenohypophysis has not finished. A compression of the adenohypophyseal vesicle is exerted by the neurohypophysis. The latter, as can be seen in a 12-day old specimen, finally, will be almost completely wrapped into the adenohypophysis. The adenohypophysis of the newborn and early pouch-young shows substantial growing on the basis of mitoses mainly in the pars intermedia, but in the pars distalis, too. Cytodifferentiation in the newborn, light microscopically, is indicated by an increasing heterogeneity of cell morphology which is most obvious in the cranial and caudal regions of the median sections. Electron microscopically, the presence of small quantities of granules as well as small quantities of golgi membranes and ribosomal endoplasmic reticulum, respectively, gives evidence of a beginning synthesis activity in the newborn.     

Systemic and pituitary pars intermedia antioxidant capacity associated with pars intermedia oxidative stress and dysfunction in horses

OBJECTIVE: To determine whether a deficiency in systemic or local (pars intermedia) antioxidant capacity is associated with pituitary pars intermedia oxidative stress and pituitary pars intermedia dysfunction (PPID) in horses. SAMPLE POPULATION: Blood samples from 20 horses with PPID and 20 healthy client-owned horses, archived paraffin-embedded adrenal gland and substantia nigra tissues from 20 horses, and pituitary gland tissue from 16 horses. PROCEDURES: Total glutathione, superoxide dismutase, and glutathione peroxidase activities were determined in RBCs. Accumulation of a systemic marker of oxidative stress (3-nitrotyrosine) was assessed in plasma and formalin-fixed, paraffin-embedded adrenal gland and substantia nigra tissues. Local antioxidants (total and manganese superoxide dismutase, glutathione peroxidase, and total glutathione) were measured in pars intermedia tissues. RESULTS: No significant differences existed in systemic antioxidant enzyme activity or accumulation of 3-nitrotyrosine between horses with PPID and control horses. In pituitary gland tissues, glutathione peroxidase activity was increased in horses with oxidative stress, whereas total glutathione concentration and superoxide dismutase activity remained unchanged. There was an age-associated decrease in manganese superoxide dismutase activity in the pars intermedia. CONCLUSIONS AND CLINICAL RELEVANCE: There was no evidence of systemic accumulation of oxidative stress markers or deficiencies in antioxidant capacity in horses with PPID, suggesting that these are unlikely to be major predisposing factors in the development of PPID. Manganese superoxide dismutase activity in the pars intermedia decreased significantly with increasing age. Role of an age-associated decrease in antioxidant capacity for the pars intermedia in the development of PPID in horses warrants further investigation.     

A histochemical investigation of different distribution of TSH cells in adenohypophsis of female and male rats

The aim of the present study was to investigate histochemically the localization of thyroid-stimulating hormone (TSH) cells and the number of TSH cells in adenohypophysis of ovariectomized adult females, intact females at estrous and diestrous phase of sexual cycles and castrated and non-castrated adult male rats. TSH cells, distributed throughout the pars distalis in all groups, were observed more frequent in areas near to the pars intermedia than other regions. The cells were round, ovoid, stellar-shaped and had contacts with sinusoids. Their nuclei were large and round-shaped. The cells were found mostly single or occasionally in groups of double and triple. The number of TSH cells was higher in estrous than diestrous phase in intact rats. In adenohypophysis of ovariectomized rats, their numbers were less than that of intacts in estrous, but higher than that of found in diestrous phases. Furthermore, the numbers of TSH cells in intact females during estrous phase was higher than those found in intact and castrated male rats. On the other hand, castration reduced the number of TSH cells while ovariectomy had no effect in this respect.     

Central Diabetes Insipidus in a Dog With a Pro-Opiomelanocortin-Producing Pituitary Tumor ot Causing Hyperadrenocorticism

Central diabetes insipidus was diagnosed by vasopressin measurements during hypertonic stimulation in a 9-year-old male giant Schnauzer with polyuria and polydipsia. The impaired release of vasopressin was believed to be caused by a large pituitary tumor, which was visualized by computed tomography. Studies of the function of the anterior lobe and the pars intermedia of the pituitary gland were conducted, and high concentrations of ACTH and α-melanotrophic hormone (α-MSH) were found without concomitant hyperadrenocorticism. Studies of the molecular size of the immunoreactive ACTH in plasma by gel filtration revealed that most of the circulating immunoreactivity was not ACTH but its precursor pro-opiomelanocortin (POMC) and low-molecular-weight POMC-derived peptides. The pituitary tumor of this dog probably originated from melanotrophic cells of the pars intermedia. The sensitivity of the pituitary-adrenocortical system for the suppressive effect of dexamethasone was unaffected.     

Cytological, Immunocytochemical and Ultrastructural Study of GH Cells of Pars Distalis Adenohipophysaria of Kids (Capra hircus)

Staining and histochemical methods, immunocytochemical and electron microscopy were used to individualize the somatotropic or GH cells in the adenohypophyseal pars distalis of the kid. They are found in a sagittal section throughout the pars distalis constituting 34% of the hypophyseal cell population. They are 12.37 micron in size and have as an ultrastructural characteristic secretory spherical granules of a large size (males, 391 nm and females, 427 nm) which are very electrodense.     

Immunocytochemical and morphometric studies on the pars distalis of the golden hamster from perinatal to senile stage

Six cell types of the pars distalis were studied from perinatal to senile stage in the golden hamster in combination with morphometric analysis and immunocytochemistry. GH cells occupied only a small area at 15 days of gestation and increased remarkably after birth to occupy a significantly larger area in the young adult than that in the other stages. PRL cells first appeared at 3 days after birth and increased rapidly thereafter to be distributed throughout the pars distalis. They always occupied a larger area in females than in males from 3 weeks after birth onward. ACTH cells were distributed mainly in the peripheral region of the pars distalis. They were dominant at 15 days of gestation, but relatively decreased after birth. The gonadotrophic cells were divided into LH cells and FSH cells. About 70% of LH cells were also immunoreactive to anti-FSH serum. LH cells occupied a larger area than that of FSH cells in every stage examined. TSH cells occupied the second largest area at 15 days of gestation, but rapidly decreased at 3 weeks after birth to occupy the smallest area among the immunoreactive cell types throughout the life-span. The chronological changes in the percentages of all cell types constituting the pars distalis seemed to reflect the activity of these cell types at a given stage.     

Hypertrichosis in a horse with alimentary T-cell lymphoma and pituitary involvement.

A 13-year-old Quarterhorse mare had a 6-month history of diarrhea, progressive weight loss, and lethargy. At presentation the mare was hirsute, had hyperhidrosis, and abnormal fat distribution in addition to severe diarrhea. A presumptive clinical diagnosis of protein-losing enteropathy and pituitary pars intermedia dysfunction was made. T-cell lymphoma was diagnosed in a rectal biopsy specimen. The owner elected to euthanize the mare because of poor prognosis and the severity of the disease. At necropsy, the mare had hypertrichosis and the pituitary gland was diffusely enlarged. Histologically, neoplastic lymphocytes infiltrated the gastrointestinal mucosa, mesenteric lymph nodes, and the pituitary gland. In addition, there was hyperplasia of the pituitary gland pars intermedia. Pituitary adenoma was not present. Hypertrichosis in this case could have been triggered by a combination of adenomatous hyperplasia of pars intermedia and lymphoma resulting in disruption of the hypothalamic dopaminergic tone or disruption of the hypothalamic thermoregulatory center.     

Distribution and implications of beta-endorphin and ACTH-immunoreactive cells in the intermediate lobe of the hypophysis in healthy equids

The distribution of cells that stain positive for beta-endorphin and ACTH immunoreactivity was studied in the pars intermedia (PI) of the hypophysis in 3 healthy horses and 2 healthy ponies. Serial sections treated with commercial antibodies generated against beta-endorphin or ACTH were processed for immunocytochemical studies, using the avidin biotin immunoperoxidase-complex method. Distribution patterns of cells reacting with antibodies were similar in cells from all equids. Cells immunostained for ACTH were numerous and widely distributed in the PI. Cells immunopositive for ACTH probably contain corticotrophin-like intermediate lobe peptide that cross-reacts with antisera to ACTH. Cells immunopositive for beta-endorphin were fewer in number and had a more limited distribution in the PI. Most beta-endorphin-positive cells were located along the border of the PI adjacent to the lobus nervosus and had abundant eosinophilic cytoplasm when stained with hematoxylin and eosin. Cells with prominent eosinophilic cytoplasm were not common in other areas of the PI. When serial sections were examined, cells that stained positive for beta-endorphin immunoreactivity also appeared positive for ACTH.     

妊娠期山羊腺垂体中催乳素促卵泡素和促黄体素的分布特点

为了阐明妊娠期垂体中催乳素(PRL)、促卵泡素(FSH),促黄体素(LH)的分布和三者之间协调关系.本试验采用免疫组化SP法检测了PRL、FSH,LH三种激素在妊娠各期山羊的腺垂体细胞中免疫反应产物的分布特点.结果显示,在山羊妊娠过程中,腺垂体中PRL阳性细胞多存在于远侧部,数量逐渐增多,胞质呈强阳性;FSH和LH阳性细胞分布在远侧部和结节部,FSH胞质内颗粒着色深浅不一,LH多核膜着色;相对表达量都逐渐升高,而升高程度不同,表现为妊娠后期LH表达量急剧升高,FSH则变化较小,除了FSH的相对表达量在妊娠前期和中期之间无显著差异(P>0.05)外,3种激素的相对表达量在妊娠前期、中期和后期3个时期之间都存在显著差异(P<0.05),妊娠前、中期FSH的相对表达量均高于PRL和LH,妊娠后期LH的表达量最高.FSH次之,PRL最低.提示PRL,FSH和LH三种激素相互协同以促进胚胎着床并维持妊娠,而且在妊娠早期PRL起主要作用,之后协同FSH和LH维持妊娠.     

Presence of neuropeptide Y in somatotrophs of cattle

Neuropeptide Y (NPY), a 36-amino acid member of the pancreatic polypeptide family, was found to be present by immunohistochemistry in the bovine adenohypophysis. NPY mRNA expression was confirmed in the adenohypophysis by RT-PCR. NPY immunoreactivity was present in about 38% of adenohypophyseal cells in the pars distalis. However, NPY immunoreactive cells (NPY-ir cells) were scarce in the zona tuberalis. Immunohistochemistry of NPY and specific hormones using mirror sections revealed that NPY was colocalized in GH immunoreactive cells. Over 90% of somatotrophs corresponded to NPY-ir cells. These results indicate that endogenous NPY is present in the bovine somatotroph and may act as an endocrine intercellular mediator in the adenohypophysis.     

Regulation of alpha-melanocyte-stimulating hormone secretion from the pars intermedia of domestic cats

OBJECTIVE: To identify factors regulating secretion of alpha-melanocyte-stimulating hormone (alpha-MSH) from the pars intermedia (PI) of the pituitary gland of cats. ANIMALS: 28 healthy adult cats. PROCEDURE: Indwelling catheters were placed in 1 jugular vein of each of 7 to 10 cats, depending on treatment group. Sixteen hours later, 3 blood samples were collected for determination of baseline plasma hormone concentrations, and saline solution or a test substance (haloperidol, corticotropin-releasing hormone, bromocriptine, isoproterenol, insulin, or dexamethasone) was administered via the catheter. Subsequent blood samples were collected at regular intervals for up to 240 minutes after injection. Concentrations of ACTH, cortisol, and alpha-MSH were measured in plasma by use of specific radioimmunoassays. Cats were rested for at least 3 weeks between experiments. RESULTS: Administration of haloperidol and isoproterenol resulted in increased, and bromocriptine and insulin in decreased, circulating concentrations of alpha-MSH from baseline. ACTH and plasma cortisol concentrations increased after administration of all test substances except dexamethasone. Dexamethasone injection resulted in decreased plasma concentrations of ACTH and cortisol. CONCLUSIONS: Secretion of alpha-MSH from the PI of cats appears to be inhibited by dopaminergic activity and stimulated by beta-adrenergic influences. Activation of secretion of alpha-MSH from the PI can be dissociated from activation of secretion of other pro-opiomelanocortin-derived peptides, such as ACTH, arising from the pars distalis. Regulation of secretory activity of the PI of cats resembles that of rats.