Expression of intermediate filaments in neuroendocrine tumors

Expression of 160-kilodalton (kd) neurofilament, cytokeratin, and vimentin was immunohistochemically investigated in 45 pheochromocytomas, 12 medullary thyroid carcinomas, and 12 pancreatic islet cell tumors. Four mixed neuroendocrine-neural tumors, two multiple endocrine neoplasia type I tumors, and two multiple endocrine neoplasia type II tumors were included in this study. Neurofilament immunoreactivity was demonstrated in 45 (100%) of the pheochromocytomas, 10 (83%) of the medullary thyroid carcinomas, and 11 (92%) of the islet cell tumors. Cytokeratin and vimentin were detectable in 29% and 24% of the pheochromocytomas, 100% and 25% of the medullary thyroid carcinomas, and 67% and 25% of the islet cell tumors, respectively. Neurofilament was the most frequently detected intermediate filament in the neuroendocrine tumors. Cytokeratin was seen in the intra-adrenal but not the extra-adrenal pheochromocytomas. Coexpression of neurofilament and cytokeratin was common in the neuroendocrine tumors, and occasionally vimentin was also expressed simultaneously. There were no characteristic differences in the expression of intermediate filaments between multiple endocrine neoplasia type I or II tumors and sporadic-type tumors or between metastatic tumors and nonmetastatic tumors.

What's new in the localization of sex steroids in the human ovary and its tumors?

It is important to understand the distribution of steroidogenesis in steroid producing tissues in order to obtain a better understanding of steroid metabolism. Recent advances in purification and subsequent generation of antibodies against cytochromes P-450 specific for steroid hormone biosynthesis have made it possible to localize the sites of steroidogenesis immunohistochemically. This review provides the localization of sex-steroid hormone biosynthesis in normal and pathological human ovaries including sex-cord stromal tumors, hyperthecosis and Brenner tumor, as determined by the tissue distribution of immunoreactivity of individual enzymes specific for different stages of the biosynthetic process.

Myogenic expression in esophageal polypoid tumors

Four cases of esophageal polypoid tumors composed of squamous cell carcinoma and spindle cell sarcomatous components were investigated. Squamous cell carcinoma was consistently present in the base of the polypoid lesions in all four cases and was also intermingled with spindle-shaped sarcomatous cells in two cases. Metastases in the lymph nodes were observed in two cases: one was squamous cell carcinoma with a sarcomatous component and the other consisted of a pure sarcomatous component. All tumors involved at least the muscularis mucosae. In the sarcomatous region, the tumor was composed of highly anaplastic cells with or without forming interlacing fascicles. Pleomorphism was marked and bizarre giant cell forms were frequent. Mitoses were frequently present. Immunohistochemical study revealed that the anaplastic cells in the sarcomatous component in all cases were immunoreactive to desmin, muscle actin, vimentin, and alpha 1-antichymotrypsin, but were negative for cytokeratin, even in the metastatic tumors of the lymph nodes. The immunohistochemical results favor myogenic differentiation of the anaplastic cells, and these tumors were considered to be true carcinosarcomas composed of squamous cell carcinoma and leiomyosarcoma.

Demonstration of neuroendocrine cells in ovarian mucinous tumors

The frequency of argyrophil cells in mucinous cystadenocarcinomas, borderline tumors (MBT) and cystadenomas was 29.8% (14 of 47), 46.7% (7 of 15) and 11.1% (2 of 18), respectively. These were statistically higher than the frequencies in 17 clear cell carcinomas, 43 serous cystadenocarcinomas, and 24 metastatic carcinomas. Immunoreactive cells for serotonin, somatostatin, gastrin, pancreatic polypeptide, growth hormone-releasing hormone, metenkephalin, neuron-specific enolase, and chromogranin-A were detected in almost all these cases with argyrophil cells. However, immunoreactivities for glucagon, vasoactive intestinal polypeptide, and adrenocorticotropic hormone were negative in ovarian mucinous tumors. Immunohistochemical multiplicity of neurohormones was remarkable in 15 MBT (including 5 müllerian and 10 intestinal MBT) and it was not related to the number of argyrophil cells per unit tumor cells. Individual hormones demonstrated here seemed to be present in different cells, but certain cells were immunoreactive for both gastrin and somatostatin by double immunostaining. Based on the high frequency of endocrine cells, borderline tumors seemed to be unique in the spectrum of mucinous ovarian tumors.

Steroid 21-hydroxylase and 17 alpha-hydroxylase in microsomal fraction of functioning adrenocortical tumors

In order to survey the enzymic activities of steroidogenesis in functioning adrenocortical tumors, we investigated the activities of steroid 21-hydroxylase and 17 alpha-hydroxylase in microsomal fractions of 12 surgically resected adrenocortical tumors associated with Cushing's syndrome (5 adenomas and one carcinoma), primary aldosteronism (5 adenomas) and adrenogenital syndrome (AGS) (one carcinoma), and one adrenocortical hyperplasia resulting from Cushing's disease. Seven adrenal cortices from the patients with mammary carcinoma, renal cell carcinoma or pheochromocytoma were used for normal control. In normal controls 21-hydroxylase activities with progesterone as a substrate were 1.61 +/- 0.25 nmole/min/mg protein and those with 17 alpha-hydroxyprogesterone were 5.22 +/- 1.06 nmole/min/mg protein. The activity of 21-hydroxylase was higher in four cases of 5 aldosteronomas than in normal controls. Those activities in Cushing's adenomas were in the range of normal controls in this study. 17 alpha-hydroxylase activities were much variable from case to case even though in normal controls (4.50 +/- 2.40 nmole/min/mg protein), and in most cases of adenomas 17 alpha-hydroxylase activities were in the range of normal controls. Activities of both hydroxylase in carcinomas were lower than in normal controls. The present paper showed the abnormal steroidogenic enzyme activities in aldosteronomas and adrenocortical carcinomas.

Calcitonin gene-related peptide in the human hypothalamus

Calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) in the human hypothalamus was investigated by radioimmunoassay and by immunocytochemistry. CGRP-LI was detected from two hypothalami obtained at autopsy (2.1 and 7.0 ng/g wet tissue) by radioimmunoassay. Reverse phase high performance liquid chromatography revealed that most of the CGRP-LI in the human hypothalamus was eluted in an identical position with synthetic human CGRP. For immunocytochemistry, human hypothalami obtained at autopsy were fixed and cryostat-sectioned at 40 microns. Free floating sections were immunostained with antibody to CGRP. CGRP-immunoreactive cell bodies were found in the supraoptic nucleus, paraventricular nucleus and infundibular nucleus. These findings indicate that CGRP exists in the cell bodies of the supraoptic nucleus, paraventricular nucleus and infundibular nucleus in the human hypothalamus and CGRP may play some roles in the endocrine and other functions of the human hypothalamus.

Immunohistochemical demonstration of adrenodoxin reductase in bovine and human adrenals

Adrenodoxin reductase (ADR) was purified from bovine adrenocortical mitochondria and specific antibody was raised in rabbits. Immunohistochemical analysis of ADR was performed in the bovine and human adrenals. ADR was present in all of the zones in both bovine and non-pathological human adrenal cortex. In non-pathological human adrenals, the immunoreactivity was particularly prominent in the zona glomerulosa (ZG) and reticularis (ZR). Intensive immunoreactivity was observed in the ZG and some cells of the outer fasciculata and the ZR in the adrenal glands with idiopathic hyperaldosteronism. In adrenal glands with Cushing's disease, immunoreactivity was present in the compact cells of cortical micronodules. In all cases, sites of immunoreactivity correspond to sites of increased steroidogenesis. In aldosteronoma and cortical adenoma with Cushing's syndrome, the immunoreactivity was generally marked in compact cells but not in large cells with clear cytoplasm, ADR was present in the ZG and the ZR, and the ZG in the non-neoplastic adrenal glands attached to aldosteronoma and Cushing's adenoma, respectively. ADR was present in the compact cells in adrenocortical carcinoma clinically manifesting Cushing's syndrome.

Immunohistochemical studies of steroidogenic enzymes (aromatase, 17 alpha-hydroxylase and cholesterol side-chain cleavage cytochromes P-450) in sex cord-stromal tumors of the ovary

Aromatase, 17 alpha-hydroxylase, and cholesterol side-chain cleavage P-450 cytochromes (P-450AROM, P-450(17 alpha,) and P-450SCC, respectively) were immunohistochemically localized in nine granulosa cell tumors, 15 thecomas, ten Sertoli-Leydig cell tumors, two steroid cell tumors, five fibromas, and five sclerosing stromal tumors. In the thecomas, P-450SCC and P-450(17 alpha) were positive in luteinized theca cells and in cells with vacuolated cytoplasm, while P-450AROM was not observed. In the steroid cell tumors, all the P-450 cytochromes were intensely stained. P-450SCC and P-450(17 alpha) were present in cells with vacuolated cytoplasm in two cases of sclerosing stromal tumor. P-450AROM was weakly demonstrated in one of the granulosa cell tumors. P-450(17 alpha,) P-450SCC, and P-450AROM were all faintly stained in the Sertoli-Leydig cell tumors. No P-450 cytochrome immunoreactivity was observed in any fibroma.

Microvascular changes in the stroma of human colorectal carcinomas: ultrastructural histochemical study

Ultrastructural histochemical studies were performed using Ulex europaeus agglutinin-I lectin (UEA-I) and anti-endothelial monoclonal antibody BMA 120 in order to morphologically characterize the microvasculature of human colorectal carcinomas. In the normal mucosa, UEA-I and BMA 120 were bound to luminal plasma membrane of endothelial cells, usually continuously. Capillaries in the stroma of invasive adenocarcinomas showed remarkable structural changes such as swelling of endothelial cells with well-developed cell organelles and narrowing of the lumen. Reaction products for UEA-I and BMA 120 were both observed along the luminal plasma membrane of endothelial cells, usually discontinuously, partially retaining the features of normal capillaries. Furthermore, we have confirmed an occurrence of solid capillary buds composed of a strand of large endothelial cells with a trace of lumen. They showed almost no reactivity to UEA-I and BMA 120. Conventional electron microscopy revealed that they were present frequently in invasive carcinomas, but infrequently in intramucosal carcinomas and inflammatory lesions. Our results suggest that the stroma of invasive colorectal carcinomas abounds in immature capillaries and their precursors, which may indicate active tumor-induced angiogenesis.

Corticotropin-releasing hormone in the human hypothalamus. Free-floating immunostaining method

We have clearly demonstrated corticotropin-releasing hormone (CRH) immunoreactive cell bodies and nerve fibers in the human hypothalamus by immunocytochemistry using free-floating sections instead of paraffin-embedded sections. Human hypothalami were obtained at autopsy, fixed and cryostat-sectioned at 40 microns. Free-floating sections were immunostained with antibody to CRH using the Vector ABC system. Most of CRH immunoreactive nerve fibers from the paraventricular nucleus pass under the fornix, while some CRH immunoreactive nerve fibers pass beyond the fornix and some through the fornix. Then the CRH immunoreactive nerve fibers run downward, medially to the supraoptic nucleus and toward the pituitary stalk. This method of immunocytochemistry is a very sensitive and suitable means for immunocytochemical studies of neuropeptides in the human brain.

Immunohistochemical analysis of cytochrome P-450 17 alpha-hydroxylase in pig adrenal cortex, testis and ovary

Cytochrome P-450 specific for steroid 17 alpha-hydroxylation (P-450(17 alpha] was immunohistochemically observed in pig adrenal cortex, testis and ovary by the biotin-streptavidin method using a specific antibody against P-450(17 alpha) purified from neonatal pig testis. In the adrenal cortex, P-450(17 alpha) was present in the zona fasciculata and reticularis while no immunoreactivity was observed in the zona glomerulosa, confirming the absence of 17-hydroxylated steroid synthesis in the zona glomerulosa. In the testis, P-450(17 alpha) was present exclusively in Leydig cells and immunoreactivity was absent in seminiferous tubules. In the ovary, immunoreactivity was observed only in the theca interna but not in the membrana granulosa of follicles. Among the tissues examined, the relative intensity of immunoreactivity was greatest in the Leydig cells, and progressively less in theca interna cells, outer fasciculata cells and inner fasciculata and reticularis cells.

Immunohistochemical demonstration of cholesterol side-chain cleavage cytochrome P-450 in bovine and human adrenals

Cytochrome P-450 specific for cholesterol side-chain cleavage (P-450SCC) was purified from the bovine adrenal and a specific antibody was raised in rabbits. The antiserum was applied for immunohistochemical visualization of the P-450SCC in the bovine and human adrenal cortex. The immunoreactivity was intense in the zona fasciculata (ZF) and reticularis (ZR) while weak in the zona glomerulosa (ZG) in the normal adrenals. In adrenocortical hyperplasia, a marked immunoreactivity was observed in the ZG in idiopathic hyperaldosteronism and the inner ZF and reticularis particularly in cells of micronodules in Cushing's disease, corresponding to cells with active steroidogenesis. In aldosteronoma and adenoma with Cushing's syndrome, P-450SCC was generally present in compact cells of adenomas.

Immunohistochemical study of cytochrome P-45017 alpha in human adrenocortical disorders

Cytochrome P-450 specific for steroid 17 alpha-hydroxylation (P-45017 alpha) was immunolocalized in normal and hyperfunctioning adrenal glands of pigs, bovines, and humans, using a specific IgG fraction raised against the enzyme. P-45017 alpha was present in the zona fasciculata (ZF) and zona reticularis (ZR), but not in the zona glomerulosa (ZG), in pig, bovine, and human adrenal glands. In the adrenal glands of patients with Cushing's disease, the positive immunoreactivity to P-45017 alpha was intense in ZF and ZR, particularly in cortical micronodules, corresponding to the sites of active steroidogenesis. Cells of hyperplastic ZG and outer ZF in the adrenal glands of idiopathic hyperaldosteronism were negative for P-45017 alpha. In aldosteronoma, positive immunoreactivity was observed in some tumor cells, which is consistent with cortisol production and its responsiveness to ACTH in aldosteronoma. In the attached adrenal glands of aldosteronoma, the immunoreactive P-45017 alpha was clearly present in the inner ZF and ZR, suggesting persistent androgen production. In Cushing's adenoma, the positive immunoreactivity was intense in tumor cells, and the ZR of the attached adrenal glands was weakly immunoreactive.

Lectin histochemistry in adrenocortical hyperplasia and neoplasms with emphasis on carcinoma

Lectin binding analysis of Con A, SBA, PNA, WGA, HPA, RCA-I, DBA, and UEA-I was performed in two cases of normal human adrenal gland, four cases of adrenocortical hyperplasia, six cases of adrenocortical adenoma, and seven cases of adrenocortical carcinoma to examine the differences of lectin binding properties. No lectins were bound specifically to adrenocortical cells. Binding of RCA-I was observed in some carcinoma cells focally but not in benign counterparts. With WGA and Con A, the cytoplasmic binding became apparent in the cells manifesting hypercorticism. In adrenocortical carcinoma, various WGA and Con A binding patterns were intermingled, but no specific patterns were identified. The focal nature of RCA-I binding, and no specific WGA and Con A binding properties in carcinoma, suggest that diagnosis of malignant neoplasm must still largely rely on clinical, hormonal, and structural criteria in adrenocortical neoplasms.

Immunolocalization of aromatase, 17 alpha-hydroxylase and side-chain-cleavage cytochromes P-450 in the human ovary

Immunohistochemical localization of cholesterol side-chain-cleavage, 17 alpha-hydroxylase and aromtase cytochromes P-450 was performed in 35 morphologically normal human premenopausal ovaries by using specific antibodies against the enzymes. In well-developed ovarian follicles in the late stages of follicular growth, immunoreactivity of P-450AROM was only seen in granulosa cells while P-450(17 alpha) and P-450SCC activity was confined to theca interna cells, confirming that follicular oestrogen is produced in granulosa cells by the aromatization of androgens derived from the theca interna cells. In the corpus luteum, this functional differentiation is maintained, since immunoreactivity of P-450AROM was exclusively present in luteinized granulosa cells while that of P-450(17 alpha) was present in luteinized theca calls. Immunoreactivity of P-450SCC was present in both types of cells in the corpus luteum.

Coexpression of cytokeratin, neurofilament and vimentin in carcinoid tumors

The immunohistochemical expression of intermediate filaments was investigated in 56 carcinoid tumors from 50 cases including 31 rectal and 25 non-rectal sites. Cytokeratin was the most frequently expressed in 55 of the tumours. Only one tumour of the stomach was negative for cytokeratin. Neurofilament (68 kd and 160 kd) was positive in 25 (44.6%) tumours with no preferential pattern of expression in particular tumours. Vimentin was positive in 18 out of the 31 rectal carcinoids (58%), and 3 of the 25 non-rectal carcinoids (12%). There was a significant difference in vimentin immunoreactivity between rectal and non-rectal carcinoids. The coexpression of cytokeratin and neurofilament was 44.6% and that of cytokeratin and vimentin was 37.5%. The coexpression of all three types of intermediate filament was 35.5% in rectal carcinoids, but 8% in non-rectal carcinoids. The present study revealed coexpression of cytokeratin, neurofilament and vimentin in carcinoids and an especially high incidence of vimentin expression in those of rectal origin.

Calcitonin gene-related peptide-like immunoreactivities in pheochromocytomas

Calcitonin gene-related peptide (CGRP) is reported to exist in high concentrations in plasma and tumor tissues of medullary thyroid carcinomas. CGRP-like immunoreactivity (LI) in tumor tissues of pheochromocytomas was investigated by radioimmunoassay. CGRP-LI in 9 pheochromocytomas ranged from 0.50 to 1240 ng/g wet tissue. Sephadex G-50 column chromatography revealed that most of CGRP-LI in tumor extracts was eluted in an identical position to synthetic human CGRP. Reverse-phase high pressure liquid chromatography revealed that CGRP-LI in tumor extracts was eluted in an identical position to synthetic human CGRP and in a more hydrophobic position. These results indicate that high concentrations of CGRP-LI also exist in tumor tissues of pheochromocytomas.

Melanin-producing medullary thyroid carcinoma with glandular differentiation

A rare case is reported of melanin-producing medullary thyroid carcinoma in a 62-year-old man. Intraoperative imprints of the thyroid tumor revealed numerous detached tumor cells containing large amounts of brown pigment. The Fontana-Masson argentaffin reaction with bleach confirmed that those granules were melanin. Histologically, the tumor was composed of two different components--a medullary area with hyalinized stroma and a follicular area. Melanin was scattered in both areas. The tumor cells in both areas were immunoreactive to carcinoembryonic antigen, calcitonin, gastrin-releasing peptide, somatostatin, met.-enkephalin, neuron-specific enolase, chromogranin and neurofilaments, and negative for thyroglobulin and S-100 protein. The histologic diagnosis was melanin-producing medullary thyroid carcinoma with glandular differentiation. Although various kinds of peptides and amines have been reported to be produced in medullary thyroid carcinoma, melanin production is quite rare; this appears to be only the third reported case.

Immunohistochemical demonstration of steroid C21 hydroxylase in normal and neoplastic human breasts

Steroid C21 hydroxylase was investigated immunohistochemically with the use of antibody against cytochrome P-450 specific for steroid C21 hydroxylation (P-450C21) in normal and neoplastic human breast tissues. In the histologically normal breast, P-450C21 was exclusively present in secretory tubules and ducts. In mammary dysplasia and fibroadenoma, P-450C21 was intensively stained in epithelial cells. In gynecomastia, P-450C21 was faintly observed in epithelial cells in some cases. In intraductal and invasive ductal carcinoma, P-450C21 was observed in the cells with ductal formation. P-450C21 was not observed in medullary and mucinous carcinoma. In lobular carcinoma, only two cases were positive for P-450C21 of nine cases examined. P-450C21 is considered to be closely related to the ductal differentiation in neoplastic transformation of the breast.

Distribution of Crooke's cells and ACTH cells in the human pituitary glands

Distribution of ACTH cells and Crooke's cells in the human pituitary glands was studied in 5 autopsy cases. ACTH cells were distributed throughout the anterior pituitary lobes, in particular densely in their anterior halves. Some ACTH cells were found in the posterior pituitary lobes in three cases. Crooke's cells were distributed limitedly in the anterior halves of anterior pituitary in two cases. In the remaining three cases, Crooke's cells were widely distributed in the anterior pituitary lobes but predominantly in their anterior halves. No Crooke's cells were found in the posterior pituitary. These findings suggest that cells in the anterior part of anterior pituitary are more likely to show Crooke's hyaline change than those in the other parts.

Ultrastructural immunolocalization of lysozyme in paneth-like cells in undifferentiated (gastric)-type carcinoma of the stomach

Five cases of gastric carcinoma of undifferentiated (gastric) type containing Paneth-like cells were studied by immunoelectron microscopy for lysozyme using two methods. The Paneth-like cells in these carcinomas had lost their cellular polarity and possessed electron-dense granules. These granules varied in size (0.5-3 micron in diameter), electron density and shape. Post-embedding method revealed immunolocalization of lysozyme in these granules in all cases, similar to that in normal Paneth cells. Pre-embedding method showed immunoreactivity diffusely or focally located in the cytoplasm, but this approach was unable to reveal immunoreactivity in the granules, a feature also common to normal cells. Our study therefore confirmed that Paneth-like carcinoma cells and normal Paneth cells had the same features, and indicated that undifferentiated-type gastric carcinoma could possess specially differentiated cells, providing further support that such carcinoma could express multipotentiality. The difference in the results obtained by the two immunoelectron microscopy methods was discussed.

11 beta-Hydroxylase in mitochondrial fractions of functioning and non-functioning adrenocortical tumors

The activity of 11 beta-hydroxylase was investigated in the mitochondrial fractions of 19 surgically resected adrenocortical tumors associated with Cushing's syndrome (4 adenomas and 2 carcinomas), primary aldosteronism (8 adenomas), adrenogenital syndrome (AGS) (2 carcinomas) and no hormonal symptoms (3 adenomas). Five adrenal cortices from patients with mammary carcinoma, renal cell carcinoma and pheochromocytoma were used for the normal control. The activities of 11 beta-hydroxylation of deoxycorticosterone and of 11-deoxycortisol in the control adrenal cortices were 0.66-2.16 pmole/mg protein/min (mean: 1.28 pmole/mg protein/min) and 0.25-0.77 pmole/mg protein/min (mean: 0.56 pmole/mg protein/min), respectively. The activities in adenomas and carcinomas associated with Cushing's syndrome were in the range of normal control. The activities in aldosteronomas were significantly higher in 4 cases than those of the normal control and in the range of the normal control in 4 cases, suggesting that the higher activity of 11 beta-hydroxylase is one of the important factors causing mineralocorticoid excess. The activities in adrenocortical carcinomas with AGS were significantly lower, corroborating clinical findings of androgen excess with suppressed production of mineralocorticoid or glucocorticoid. The activities in two cases of nonfunctioning adenomas were in the range of the normal control, but the third case showed higher activity than the normal control. These results show that the abnormal activity of mitochondrial 11 beta-hydroxylase exists in some aldosteronomas, non-functioning adrenocortical adenomas and carcinomas with AGS.

Immunohistochemical demonstration of steroid C-21 hydroxylase in normal and neoplastic salivary glands

The presence of steroid C-21 hydroxylase in normal and neoplastic salivary glands was investigated immunohistochemically with the use of antibody against cytochrome P-450 specific for steroid 21-hydroxylation (P-450C21). In normal salivary glands, P-450C21 was exclusively present in the excretory duct system (intercalating, striated and large excretory ducts), and not observed in acini. In salivary gland tumors, P-450C21 was observed in most epithelial cells of duct origin within pleomorphic adenomas including cells of amorphous groups scattered in myxoid areas, and in adenolymphoma. Some mucous cells in mucoepidermoid tumor also were positive for this enzyme. These findings in the normal and neoplastic salivary gland suggest that the expression of P-450C21 is closely related to ductal differentiation.

Immunohistochemical localization of cytochrome P-450C21 in human adrenal cortex and its relation to endocrine function

Cytochrome P-450C21 was successfully demonstrated in the human adrenal glands by a peroxidase-antiperoxidase method. All three cortical layers were stained in the normal adrenal glands, particularly the zonae glomerulosa and reticularis. Well-stained and faintly stained cells were intermingled in the zona fasciculata, suggestive of intrazonal variations. The immunoreactivity was particularly intense at the site of ACTH action, i.e., cells in micronodules and cells around myelolipomatous lesions in adrenocortical hyperplasia of Cushing's disease and sites of regeneration in the normal adrenal glands. In adrenocortical adenomas with Cushing's syndrome and primary aldosteronism, cells with large nuclei were generally stained well. In the adrenocortical tissue adjacent to a functioning adenoma, the immunoreactivity was observed only in the zona glomerulosa, especially in cases of primary aldosteronism. This finding is consistent with morphologic observations.

The development and morphogenesis of the human pituitary gland

In order to clarify the environmental factors which are involved in the development of the primordium of the pituitary gland such as cell-cell interactions, a three-dimensional reconstruction of this organ and its surrounding tissues was carried out. Pituitary material was obtained from human fetuses mainly during the period of organogenesis. Rathke's diverticulum was found to stretch rostrally from the stomodeal epithelium to the middle of the mesoderm, and already by the 5th week of fetal growth, it was clearly seen to be involved with the diencephalon. The area of contact between Rathke's pouch and the diencephalon gradually moved from the rostral to caudal regions and, after 13 weeks of development, had a position similar to that found in the newborn infant. Among the cells forming Rathke's pouch, it was found that the closer their relationship was to the diencephalon, the greater were their epithelial characteristics. When the relationship of such cells to the diencephalon was weaker, their differentiation to endocrine cells occurred earlier. Immunohistochemically, that portion of the pituitary primordium which has a close relationship with the diencephalon, later to become the pars intermedia, showed an adrenocorticotropic hormone (ACTH) immunoreactivity later than that of the pars anterior. On the other hand, in the 21st fetal week, nearly all of the cells of the pars intermedia were found to be ACTH-positive. This finding is thought to indicate a close connection between the physical contact between the brain (diencephalon) and the pituitary primordium and the development of the pars intermedia; the differentiation of ACTH cells. The surface of the epithelium of Rathke's cavity continues to increase at least until the 21st fetal week, so the growth of the epithelium of Rathke's pouch is thought to be heavily involved in the growth of the primordium of the pituitary gland in the early stages of development.