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Regulation of the Pituitary Gland by Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
The mature posterior pituitary gland in humans consists of distal axons of hypothalamic neurons and their terminals, specialized supportive astroglia known as pituicytes, which surround the terminals, and capillaries that originate from branches of the carotids. During embryogenesis, the gland is formed by evagination of neural tissue from the floor of the third ventricle. After its downward migration, the neurohypophysial tissue becomes encapsulated by the ascending oral ectodermal cells of Rathke’s pouch, which eventually form the anterior pituitary. In humans, this development is completed by the end of the first trimester, and the two major neurohypophysial hormones, arginine vasopressin (AVP), also called antidiuretic hormone (ADH), and OT, are already detectable in the neurohypophysial tissue at this time [1].
Neural Control of Adenohypophysis
Published in Paul V. Malven, Mammalian Neuroendocrinology, 2019
Tanycyte ependymal cells in the median eminence and basal hypothalamus project their processes onto primary portal capillaries, as illustrated in Figure 4-3, as well as onto ordinary capillaries and neuronal processes. The functions of these tanycyte projections onto neurons are not known. One other cell type found in the median eminence and not depicted in Figure 4-3 is the neuroglial cell. This cell is called a pituicyte when it is located in the pars nervosa, but that term is not used here. Except for a few sparse neuronal perikarya, neuroglial and tanycyte ependymal cells are the elements in the median eminence that contain ribosomes and rough endoplasmic reticulum (RER). This unique feature aids greatly in the interpretation of transmission electron micrographs. If a process contains RER, it can probably be identified as a non-neuronal process. Otherwise it would sometimes be difficult to distinguish ultrastructurally between axonal terminations and non-neuronal processes.
Major Digestive and Endocrine Glands
Published in George W. Casarett, Radiation Histopathology: Volume II, 2019
The neurohypophysis consists largely of nonmyelinated nerves of the hypothalamo-hypophysial tract enclosed in a protoplasmic sheath by cells called pituicytes, but in the posterior lobe the nerve fibers and the pituicytes become disassociated and run parallel courses, each ending with processes on pericapillary connective tissue. It is believed that the neurohypophysial granules called Herring bodies represent neurosecretory material formed in the cells of the supraoptic and periventricular nuclei, transported along the nerve fibers and stored at nerve terminals in the infundibular process. The neurohypophysial hormones include oxytocin which causes contraction of the smooth muscle of the uterus, and vasopressin which raises blood pressure by causing contraction of the smooth muscle in small blood vessels and which also performs an antidiuretic action by promoting reabsorption of water in the kidney (mainly in the thin segment of the loop of Henle).
Histopathological evaluation of the effects of dexmedetomidine against pituitary damage ınduced by X-ray irradiation
Published in Biomarkers, 2023
Filiz Mercantepe, Levent Tumkaya, Tolga Mercantepe, Sema Rakici
On examination of sections stained with haematoxylin and eosin under a light microscope, the pituitary tissues of the control group had adenohypophysis tissue composed of normal chromophobic acidophilic and basophilic cells. We also observed normal pituicytes and neurohypophysis tissue with non-myelinated axons (Figure 1a and b, Table 2, HHS: 0.5(0-1)). In contrast, in sections obtained from the x-ray irradiation group, we observed many necrotic chromophobic and chromophilic cells in adenohypophysis tissue accompanied by diffuse vacuolar accumulation in the cytoplasm. Similarly, we determined necrotic pituicytes with diffuse vacuolar content in the neurohypophysis. In addition, there were extensive oedematous areas and vascular congestions caused by necrotic cells in both the adenohypophysis and neurohypophysis (Figure 1c and d, Table 2, HHS: 6(6-7)). On examination of the pituitary tissue sections of the dexmedetomidine treatment group under a light microscope, we observed necrotic chromophobic, chromophilic cells in adenohypophysis tissue and cells with fewer necrotic pituicytes in neurohypophysis tissue. We also determined a reduction in oedematous areas and vascular congestion in both the adenohypophysis and neurohypophysis (Figure 1e and f, Table 2, HHS: 2(1-2)).
Correlations between clinical hormone change and pathological features of pituicytoma
Published in British Journal of Neurosurgery, 2018
Ting-Wei Chang, Ching-Yi Lee, Shih-Ming Jung, Hung-Yi Lai, Chun-Ting Chen, Mun-Chun Yeap, Chi-Cheng Chuang, Peng-Wei Hsu, Chen-Nen Chang, Po-Hsun Tu, Shih-Tseng Lee
Pituicytoma is a low-grade glioma that arises from the pituicytes in the neurohypophysis, which are mostly located in the posterior lobe of the pituitary or the pituitary stalk.1 Pituicytoma is rare and usually occurs during adulthood, with a slightly higher incidence among males.2 Clinically, pituicytoma can be easily misdiagnosed as nonfunctioning pituitary adenoma due to mass effect,3 and its symptoms include headaches, visual field defects, and hypopituitarism. Occasionally, a pituicytoma is found accidentally during autopsy;4 pituicytoma-induced spontaneous suprasellar haemorrhage has also been reported.5 Notably, patients with pituicytoma who also present with hormone changes are unusual, and their hormone change is mostly triggered by tumour-related mass effect (e.g. hypopituitarism and hormone suppression).6 However, at our institute, we determined that most patients with pituicytomas also presented with hormone elevation. These patients were considered to have a functioning pituitary adenoma before pathological diagnosis. After a review of the English literature, only two case reports of pituicytoma with hormone elevation were found; in both, the patients presented with Cushing disease.7,8 These reports also provided some indications of hormone elevation, but lacked sufficient pathological and immunohistochemical (IHC) examination to confirm this phenomenon. It is unclear whether pituicytoma influences endocrine secretory functions or whether it can raise a normal pituitary gland to hypersecretory status; there has also been no analysis of coexisting pituicytoma and functioning pituitary adenoma tumours. Therefore, this study was designed to elucidate the relationship between pituicytoma and the pituitary gland.
Electron microscopic study on the effect of chronic fluoxetine treatment on pituitary gland and the possible therapeutic effect of adipose-derived mesenchymal stem cells in adult male albino rats
Published in Ultrastructural Pathology, 2022
Nashwa S. Wahba, Assmaa O. Seliem, Enas G. Abd Allah, Maha Z. Mohammed
In the current study, pars nervosa at the ultra-structural level showed a major type of pituicyte with apoptotic nuclei. Numerous pituicytes showed small granulated cytoplasm and euchromatic nuclei. In addition, most terminal axons were dilated and showed electron-lucent axoplasm with glycogen particles.