Noninvasive investigation of asymmetrically conjoined tripus twins with features of rachipagus, parapagus dicephalus, and cephalopagus.

A hypothetical mechanism for conjoined twinning postulated by Spencer ([2003] Developmental Malformations and Clinical Implications, Baltimore: Johns Hopkins University Press, p 1-476) suggests that, after separation, monovular twins fuse in one of eight predictable homologous sites. The tripus fetal specimen under study embodies characteristics of three types therefore preventing it from classification into a simple variant of any one of the eight twin types described by Spencer. The aim of this study was to reveal internal structural anomalies of the fetal specimen by using magnetic resonance imaging and computerized tomography. Dorsally appended to the primary twin is a secondary head mass (brain tissue and ocular globe) and two spinal columns converging at T4/T5, suggesting rachipagus twinning. The ventral orientation of the secondary twin's (right lateral) lower limb suggests parapagus twinning. The caudal divergence of the spinal columns and the presence of a secondary hemipelvis, separate from the primary pelvis, suggest cephalopagus twinning. Measurements of the long bones indicate a gestational age of ∼20-23 weeks. Secondary malformations of the primary fetal body include anencephaly, cleft palate, renal agenesis, decreased left ventricular outflow, and a prematurely terminating descending aorta. This study demonstrates the possibility of using current imaging techniques to study very old, formalin-preserved human material for documentation and scientific discussion without destroying the specimen, thus keeping it intact for posterity.

Investigation of a cyclopic, human, term fetus by use of magnetic resonance imaging (MRI).

Using magnetic resonance imaging (MRI), the internal neural and craniofacial malformations of a cyclopic fetus are described. External facial features were characterized by a tubular proboscis situated above a single eye slit. The brain was recognized as 'pancake' type alobar holoprosencephaly (a condition where the undifferentiated telencephalon partially surrounds a monoventricle). Displacement of some bones that normally contribute to the orbit could be clearly discerned. Absence of neural structures (e.g. falx cerebri, corpus callosum) and missing components of the ethmoid bone indicated a midline deficit. This correlates with proposed theories of cyclopic embryopathy, which suggest that the prechordal plate and the neural crest cells are affected during the third week of gestation in cyclopia.

Ultrastructural changes in rat mammotropes following incubation with dopamine.

Cultured mammotropes incubated with dopamine for one hour exhibited changes in ultrastructure indicative of actively depressed biosynthetic and secretory activity. Peripheral relocation of rough endoplasmic reticulum appeared to create a barrier to secretory granule release by exocytosis. A decrease in the numbers of secretory granules indicated a decrease in prolactin production and enhanced lysosomal activity.

Crystalloid inclusions in folliculostellate cells of adenohypophysis following estrogen withdrawal from primed male rats.

Crystalloid inclusions were observed within nongranulated, folliculostellate pituitary cells 72 after estrogen was withdrawn from primed male rats. Like crystalloid inclusions in macrophages reported by others, those observed in this study were associated with structures that appeared to be lysosomes. We suggest that crystalloid inclusions may be the result of phagocytosis, a function of folliculostellate cells proposed by us in a previous study.

Prolactin crinophagy is induced in the estrogen-stimulated male rat pituitary.

The phenomenon of crinophagy in rat pituitary mammotrophs, or lysosomal uptake of prolactin secretory granules, was confirmed by means of double-label immunogold electron microscopy, and shown to be induced in estrogen-stimulated male rats. Rabbit antibodies to rat cathepsin D were used to label lysosomes, and to rat prolactin to label secretory granules. The pituitaries were fixed in 4% formaldehyde and 1% glutaraldehyde, embedded in Lowicryl K4M, and thin sections were exposed successively to primary antibodies, biotin-labelled second antibodies, and streptavidin-gold, with an amplification procedure for cathepsin D. Cathepsin D and prolactin were detected separately on opposite sides of the sections, using 5-nm and 15-nm gold particles. Lysosomal uptake of prolactin secretory granules was not observed in untreated control rats. It was detected in about 26% of lysosome-containing mammotroph cell sections in estrogen-stimulated rats and at 7 h after estrogen withdrawal, but fell to 14% at 24 h and to 2% at 72 h after estrogen withdrawal.

Localization of acid phosphatase in lysosomes of pituitary folliculo-stellate cells following estrogen withdrawal from primed male rats.

Acid phosphatase was localized in lysosomes of non-granulated, folliculo-stellate pituitary cells 72 h after estrogen was withdrawn from primed male rats. The appearance of lysosomes and the accumulation of lipid droplets in folliculo-stellate cells coincide with the clearance of lipid from pituitary mammotropes. Positive identification of lysosomes supports our proposal in a previous study that folliculo-stellate cells are phagocytic.

Endocrine cells in the gastrointestinal tract of a stomachless teleostean fish.

Endocrine cells in the gastrointestinal tract of the stomachless teleostean fish, Notemigonus crysoleucas, were studied using electron microscopy. Located between the absorptive cells of the intestinal epithelium, the enteroendocrine cells were very few in number. While some of the cells had their secretory granules located basally and a long narrow part extending toward the lumen, many appeared rounder and the plane of the section did not indicate that they extended to the lumen. Based upon size and shape of secretory granules, there appear to be several different types of cells: those with the smallest granules distributed throughout the intestine, those with intermediate sized granules more commonly found in the middle and distal segments and a few with large granules seen most often in the distal intestine.

Pulsatile release of immunoreactive luteinizing hormone (irLH) in hypophysectomized male rats.

The concentration of plasma luteinizing hormone (LH) was monitored every minute by radioimmunoassay in male rats that were either hypophysectomized, or castrated and hypophysectomized. Castrated rats showed a pulsatile fluctuation of plasma immunoreactive LH (irLH) concentration with an elevated basal level, confirming previous work. The hypophysectomized and castrated hypophysectomized rats also showed pulsatile changes in plasma irLH concentration. This unexpected result indicates that ectopic irLH is not only actively released after hypophysectomy, but is released in pulses. The pulse interval was approximately 20 minutes for all 3 groups. The slope of the rate of decline of plasma irLH in the castrated rats is parallel to a theoretical disappearance rate of 5 min, while these slopes in the hypophysectomized and castrated hypophysectomized rats correspond to a 1 to 2-min disappearance rate. The difference in these slopes implies that the two irLH molecules may not be identical.

A possible phagocytic role for folliculo-stellate cells of anterior pituitary following estrogen withdrawal from primed male rats.

Ultrastructural changes suggesting a phagocytic role for the nongranular folliculo-stellate cells of the anterior pituitary are investigated in estrogen-primed male rats after withdrawal of estrogen. Morphological changes in mammotropes following the removal of a subcutaneous estradiol-containing Silastic implant include the formation of intracellular lipid bodies. These lipid bodies appear to be associated with enhanced estrogen-dependent prolactin secretion in mammotropes. Seven and 24 h after estrogen withdrawal intracellular lipid within mammotropes seems to be released into the intercellular space. Seventy-two h after estrogen withdrawal, lipid droplets are almost entirely cleared from mammotropes while folliculo-stellate cells become packed with lipid globules. Folliculo-stellate cells also undergo dramatic hypertrophy 7 and 24 h after the removal of E2-containing implants. Extensive intercellular junctions including zonulae adhaerentes, desmosomes, and putative gap junctions are formed. Intercellular junctions delineate extravascular channels into which numerous microvilli project. Folliculo-stellate cells appear capable of accumulating many lipid droplets, presumably related to mammotrope metabolism. What appear to be large secondary lysosomes as well as the lipid droplets are observed within folliculo-stellate cells; lipid, therefore, may be degraded through a lysosomal pathway in folliculo-stellate cells.

Dopamine-induced physical barrier to inhibit prolactin release in mammotrophs disappears during resumption of prolactin secretion.

After finding that dopamine can cause extensive changes in mammotroph ultrastructure within 2 min of administration, we further examined mammotrophs 20 and 40 min after dopamine injection when prolactin secretion had resumed. Dopamine (1,000 micrograms/kg) was injected into the right atrium of estradiol-primed male rats through indwelling cannulae. Rats were killed by decapitation 2, 20 and 40 min after dopamine treatment and their pituitaries were processed for electron microscopy. Within 2 min of administration, dopamine completely stopped prolactin release and significant changes in mammotroph ultrastructure were observed: peripheral relocation of rough endoplasmic reticulum (RER) ('dopamine barrier'); fewer secretory granules in close proximity to the cell membrane; fewer exocytoses, and increased numbers of 'intracellular bodies' associated with secretory granules (putative granule disposal system). 20 min following dopamine administration, when prolactin secretion had resumed, there appeared to be a breaking up of the 'RER barrier' in that more vesicular elements were seen and the amount of peripheral RER was reduced; more granules were adjacent to the cell membrane and exocytotic figures were more numerous. 'Intracellular bodies' decreased in number. By 40 min, mammotrophs appeared to resemble those of estradiol-primed controls with the RER stacked to one side of the cell and small numbers of 'intracellular bodies'. The correlation between ultrastructural changes in mammotrophs and prolactin release implies that the 'RER barrier' is part of a mechanism by which prolactin release is inhibited.

Cysteamine acts immediately to inhibit prolactin release and induce cellular changes in estradiol-primed male rats.

Cysteamine (CSH) has an inhibitory effect on the secretion of PRL, GH and TSH. The purpose of the present study was twofold: (1) to examine the short-term effects of CSH on PRL secretion, and (2) to elucidate the mechanism of action of CSH. CSH (100 mg/kg) was injected as an intra-atrial bolus to both normal and estradiol-primed male Sprague-Dawley rats. Blood samples were drawn every 2 min for 1 h and assayed for PRL. To determine if the actions of CSH involved PIF release or PIF receptors, a dopamine receptor blocking agent, pimozide (100 micrograms/kg) was given intra-atrially 1 h after the CSH injection and PRL concentration was monitored. Within 6 min after the CSH injection PRL levels in estradiol-primed rats began to fall, and by 30 min postinjection the levels were well below baseline values. Blocking the dopamine receptors with pimozide did not result in increased PRL levels, indicating that CSH was acting through some mechanism not directly involving dopaminergic PIF receptors. In a separate study, 6 min after the injection of CSH the rats were decapitated and their anterior pituitaries were removed and processed for electron microscopy. Only mammotrophs from estradiol-primed rats treated with CSH showed an extensive rearrangement of rough endoplasmic reticulum (RER) in concentric whorls around the periphery of the cells. These studies show that the inhibition of PRL secretion by CSH begins within 6 min, and is appreciable only when basal PRL levels are increased by estrogen priming.(ABSTRACT TRUNCATED AT 250 WORDS)

Dopamine creates a physical barrier to inhibit prolactin release in mammotrophs of estradiol-primed male rats.

After finding that ergocristine and somatostatin can cause extensive changes in mammotroph ultrastructure within 2 min of administration, we chose dopamine, the putative physiological prolactin-inhibiting factor, to correlate ultrastructural changes to inhibition of prolactin release. In order to choose a dose of dopamine for this study we tested the effects of 2 doses of dopamine (10 and 1,000 micrograms/kg) on inhibition of prolactin release. The higher dose of dopamine (1,000 micrograms/kg) completely inhibited prolactin release immediately (in less than 2 min) and maintained complete blockage for a period of 14 min. For the ultrastructural study we injected dopamine (1,000 micrograms/kg) in the right atrium of conscious free-moving rats through indwelling cannulae, and killed the rats by decapitation 2 min after dopamine administration. The following changes in mammotrophs were observed after the dopamine treatment: (1) increased numbers of secretory granules, (2) peripheral relocation of rough endoplasmic reticulum, and (3) increased numbers of 'intracellular bodies' (putative prolactin granule disposal system) associated with secretory granules. Because these rapid ultrastructural changes have been observed after treatment with three different compounds (dopamine, somatostatin and ergocristine), we do not believe that they are the unique effect of any one compound but the common denominator of the three compounds, i.e., inhibition of prolactin secretion being closely linked to the ultrastructural changes. We thus propose that the extensive ultrastructural changes that occurred in such a short period of time following dopamine administration are the mechanism of inhibition of prolactin release.

Endocrine cells in the gastrointestinal tracts of 3 teleostean species.

Endocrine cells of the gastrointestinal tracts of 3 teleostean species (Lepomis gibbosus, Morone americana and Notemigonus crysoleucas) were studied using several staining techniques: Masson-Hamperl argentaffin reaction, Singh's argyrophil reaction, Schmorl's ferricyanide test and MacConnail's lead hematoxylin; only the argyrophil method showed a positive reaction. In L. gibbosus and M. americana, endocrine cells of proximal (corporic) stomach were seen singly among the surface epithelial cells while those of distal (pyloric) stomach were more numerous and located in irregular patches. A small number of positive cells were found in the gastric glands of corporic stomach. A few argyrophil cells were seen among the surface intestinal epithelial cells of N. crysoleucas but none were seen in the intestines of L. gibbosus and M. americana.

Extensive ultrastructural changes in rat mammotrophs following administration of the dopamine agonist ergocristine-reflecting inhibition of prolactin release.

We have demonstrated an extensive reorganization of organelles in mammotrophs immediately following administration of ergocristine (a dopamine agonist) to estradiol-primed male rats. Our ultrastructural findings are consistent with our previous results that ergocristine can block prolactin release without any noticeable latent period. Following three-week priming of male rats with estradiol implants, ergocristine was administered by a bolus injection through an indwelling cannula. Within two min of its administration, ergocristine induced dramatic changes in the ultrastructure of mammotrophs, i.e., (1) increased numbers of secretory granules, (2) peripheral relocation of rough endoplasmic reticulum which tends to sequester secretory granules, (3) change in location of nucleus and (4) increased numbers of intracellular bodies associated with secretory granules. We suggest that the extensive ultrastructural changes that occurred in such a short period following ergocristine administration may be indications of specific factors associated with blockage of hormone release.

Ultrastructural changes rapidly induced by somatostatin may inhibit prolactin release in estrogen-primed rat adenohypophysis.

Apart from the known hypothalamic controls, which have been well documented, a myriad of compounds both endogenous and exogenous have proved effective in influencing secretion of prolactin (PRL). Recent studies have shown that somatostatin (SRIF), when injected intra-atrially as a bolus, is able to inhibit PRL secretion in vivo. However, the inhibitory effect of SRIF occurs only in adenohypophyses previously primed with estradiol. This research was undertaken to examine the ultrastructural effects of that inhibition using male Sprague-Dawley rats primed for three weeks with subcutaneous implants of estradiol. Within 2 min of injection of SRIF (1 mg/kg), the adenohypophyses were removed and processed for electron microscopy. We found dramatic changes in the estradiol-primed mammotrophs, including 1) an apparent rearrangement of rough endoplasmic reticulum (RER) into concentric cisternae, and 2) the appearance of intracellular bodies closely associated with granules. These changes were not observed in non-estradiol-primed male rats injected with SRIF which is consistent with the fact that in the normal male rats, SRIF failed to inhibit PRL secretion. These findings suggest that SRIF causes reorganization of cellular organelles so that PRL granules are sequestered thereby inhibiting secretion of PRL.

Desmosomes between mammotrophs suggest the existence of a functional syncytium.

Lactotrophs in the adenohypophysis have the apparent inherent capability to produce simultaneous secretion of prolactin from individual cells. There are two possibilities to account for this synchronized, discrete pulsatile secretion: (1) humoral communication, or (2) cell-to-cell syncytial communication. As a first step in examining the second possibility, we searched for ultrastructural evidence of intercellular contacts. The presence of desmosomes, the conventional junctions that serve to anchor adjacent cells, would be the first step in proving contact between homologous cells. In order to increase the observation of desmosomes, the population of lactotrophs in the adenohypophysis was increased by implantation of capsules containing estradiol in male Sprague-Dawley rats. The adenohypophyses were then examined by electron microscopy for indications of these intercellular bridges. Desmosomes were discovered between lactotrophs, indicating that cell-to-cell contact does exist, and suggesting that the desmosome may help the formation of a syncytium among lactotrophs, either directly or indirectly. Since an ectopic pituitary without direct help from the hypothalamus can secrete prolactin in a pulsatile fashion and since there are desmosomes between lactotrophs, it is possible that the synchronized prolactin release occurs through a direct cell-to-cell communication system which is linked by the desmosomes.

Adenohypophysis has an inherent property for pulsatile prolactin secretion.

Hypophysectomized male rats with adenohypophyses grafted under the kidney capsule (HG rat) for 3 weeks with or without estradiol implantation, were used to examine prolactin (PRL) secretion independent of hypothalamic influence. Changes in the circulating PRL concentration were monitored by taking blood samples every 2 min via an indwelling atrial cannula. The circulating PRL concentration did not remain at a constant level but fluctuated with time. When estradiol (100 microgram/kg) was administered to HG rats through the indwelling cannula the size of the PRL pulses was magnified. The ability of the grafted adenohypophyses to generate pulsatile changes in the plasma PRL indicates that the adenohypophysis possesses an inherent interlactotroph communication system to permit synchronized PRL secretion without the direct involvement of hypothalamic PRL-releasing factors or inhibiting factors.

Structure and carbohydrate histochemistry of the stomach in eight species of teleosts.

The histology and carbohydrate histochemistry of eight teleostean stomachs are compared. Three gross anatomical types of stomachs are described and their shapes appear to correlate somewhat with feeding habits. Each type can be divided histologically into a corpus and pylorus. Gastric glands, containing only one cell type, occur in the copora of all species, but are present in the pylori of esocids only. As a single cell can produce both enzymes and hydrochloric acid such cells may be comparable to those of amphibians but not mammals. Lamina propria and submucosa are indistinctly separated in corpora but better defined in pylori by an intervening muscularis mucosa. The arrangement of the muscularis into inner circular and outer longitudinal layers is the opposite of that seen in the esophagus. Gastric mucous cells show species variations in localization of epithelial mucosubstances, which in broad terms are recognized as sulfomucins, sialomucins and neutral mucosubstances. A piscivorous diet does not appear to demand any particular type of carbohydrate. Within the Centrarchidae, gastric pit cells vary in carbohydrate content from only neutral mucosubstance to only weakly acidic sulfomucin; two species contain both types. A positive PAS reaction on the surface of gastric epithelial cells is suggestive of a striated border and thus possibly absorptive function. The absence of stomachs in some teleosts and the evolutionary and dietary significances are discussed.