Localization of transferrin and its receptor in ovarian follicular cells: morphologic studies in relation to follicular development.

Granulosa cells perform an essential role in ovarian follicle and ovum development. Proliferating cells have an absolute requirement for iron, which is delivered by transferrin with subsequent intracellular transport via the transferrin receptor. Because iron and transferrin concentration increase in follicular fluid with advancing follicular maturation, the authors studied the distribution of transferrin and its receptor in rat and human granulosa cells with light and electron microscopic immunohistochemistry. Intense cytoplasmic staining was found in granulosa cells, with immunostaining enhancement occurring with advanced follicle maturation, including the periovulatory period. Immunoelectron microscopy showed transferrin throughout the cytoplasm, often in proximity to polyribosomes and vesicular structures. When transferrin was absent in the culture medium used to maintain granulosa cells, diminished transferrin immunostaining was seen. Based on these findings, the authors conclude that follicular maturation is closely related to high levels of cellular transferrin and transferrin receptor. Acquisition of transferrin occurs primarily by either ultrafiltration or facilitated diffusion, whereas de novo local synthesis does not have a major role.

Automated enzymatic measurement of lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid.

We describe methods for automated enzymatic measurement of lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid. Phospholipase C (EC 3.1.4.3) and sphingomyelin phosphodiesterase (EC 3.1.4.12) are reacted with lecithin and sphingomyelin, respectively, to liberate phosphocholine. Phosphocholine is then reacted with alkaline phosphatase, choline oxidase, peroxidase, and 4-aminoantipyrine to form a colored complex, for which the absorbance at 500 nm is measured with a centrifugal analyzer. Phosphatidylglycerol is hydrolyzed by phospholipase D (EC 3.1.4.4) to form glycerol, which is subsequently reacted with ATP and NAD+ in the presence of glycerol kinase and glycerol-3-phosphate dehydrogenase to yield NADH. The absorbance of the NADH formed is measured at 340 nm. These methods provide a simple, rapid, and accurate alternative to thin-layer chromatography for determination of phospholipids in amniotic fluid for assessment of fetal lung maturity.

Late recurrence of surgically removed prolactinomas.

The authors observed the clinical course of 24 women with surgically removed prolactinomas for a mean postoperative interval of 62 months. The frequency of late tumor recurrence and probable factors responsible for the recurrence were investigated. Hyperprolactinemia recurred in 4 of 13 patients with microadenomas (31%) 3 to 9 months after removal. In the macroadenoma group, relapse of hyperprolactinemia occurred in 10 of 11 patients (91%), an average of 26 months after the initial postoperative return to normal prolactin levels. Return of hyperprolactinemia was accompanied by radiologic evidence of tumor recurrence in all patients with macroadenoma, and in one patient with microadenoma. Of 12 tumors in which adjacent dura was available for histopathologic examination, 7 showed dural invasion. Although these seven patients had significantly higher preoperative levels of serum prolactin than the five without dural invasion, there was no significant relation between dural involvement and tumor recurrence. The probabilities of tumor recurring from multifocal adenoma or paraadenomatous lactotrope hyperplasia could not be assessed using our surgical material. The most plausible reason for the high recurrence rate of prolactinomas after apparent surgical cure, in the absence of defined anatomic abnormalities within the pituitary, is a functional abnormality of hypothalamic-pituitary control resulting from a primary hypothalamic disorder.

Choroid plexus as a barrier to immunoglobulin delivery into cerebrospinal fluid.

The concentration of gamma globulins is greatly increased in the cerebrospinal fluid (CSF) during inflammatory and degenerative disorders of the central nervous system (CNS). The mechanism by which immunoglobulins enter the CSF under normal conditions is unknown. The extent of participation of the blood-brain barrier in protein delivery to the CSF is unclear, although the choroid plexus is known to have primary responsibility for the formation and movement of certain proteins into the CSF. To investigate the role of the choroid plexus in immunoglobulin delivery to the CSF, the authors evaluated rat brain tissue by light and electron microscopic immunohistochemical technique using the peroxidase technique of immunoglobulin (Ig)G and IgA detection. Peanut agglutinin was used to identify macrophages, cells known to have important immune functions and which have been reported as a normal component of the choroid plexus. Antisera to IgG' and IgA demonstrated diffuse surface staining of the choroidal epithelial cells with light and electron microscopy; the cytoplasm and nuclei did not contain immunoglobulins. Macrophages were not present in the choroid plexus, in contrast to previous reports. The results demonstrate that immunoglobulins do not enter the CSF via the choroid plexus, unlike other proteins in similar concentrations in the CSF. In addition, macrophages are shown to be an insignificant component of the plexus, thereby further diminishing the likelihood of participation-of the choroid plexus in the regulation of immunoglobulin entry into the CNS under normal conditions.

Neuroblastoma in adults. Pathologic findings and clinical outcome.

Neuroblastoma in adults is uncommon. Previous reports have suggested that adult patients with neuroblastoma have a better prognosis than children with these tumors. We have examined the clinical features of eight adults with neuroblastoma and related these data to tumor histopathology and immunohistochemistry using an antibody to neuron-specific enolase. The results show that when children and adults with neuroblastoma are compared by stage, adults do not have a better prognosis. Adults tend to have a different anatomic distribution of primary tumor sites, with more frequent extra-abdominal sites than are seen in children. Neuroblastomas arising in adults are similar to those seen in children by containing neuron-specific enolase, an enzyme associated with cells of neuroectodermal origin. These findings show that adult neuroblastomas are similar to their childhood counterparts in clinical behavior and pathologic features.

The carcinoid syndrome: neuroendocrine and chemical considerations.

The carcinoid syndrome is characterized by a complex of neuroendocrine and chemical abnormalities whose cause is not known. Carcinoids vary in their tendency to produce the carcinoid syndrome, although ileal tumors and those that have metastasized are more frequently associated with manifestations of the syndrome. The unifying concept of a neural crest origin for these and related neoplasms provides a basis for understanding the hormonal and chemical features of this disease. The extent of the various hormonal changes is only now becoming apparent and will undoubtedly expand as investigation continues in this area.

Localization of human prealbumin in choroid plexus epithelium.

Cerebrospinal fluid (CSF) is generally considered to be derived from plasma through a combined process of ultrafiltration and secretion by the choroid plexus. However, the mechanisms ultimately responsible for achieving the final protein composition of CSF are uncertain. Some proteins, in particular prealbumin, are present in quantities not easily explained by usual physicochemical considerations. To investigate the possibility of de novo synthesis by choroid epithelium, we have examined human choroid plexus an ependyma for the presence of prealbumin. Using the peroxidase-antiperoxidase method at the light and electron microscopic level, as well as immunofluorescence, we localized prealbumin in choroid epithelial cytoplasm on the endoplasmic reticulum and in association with the Golgi apparatus. Ependymal cells and stroma did not reveal immunocytochemical labeling. These findings indicate that the choroid plexus epithelium contributes to the final CSF composition by de novo protein synthesis.