Studies of Brunner's glands in the opossum. I. Adult morphology

The duodenal glands of the adult opossum form a lobed, glandular collar in the submucosa immediately distal to the pyloric sphincter. They empty into funnel-shaped mucosal depressions. The depressions, which form two or three irregular rows that run parallel to the pyloroduodenal junction, are lined by either pyloric or intestinal epithelium. An individual gland of Brunner has an extensive intralobular duct system which terminates in a single excretory duct just prior to entry into a depression. Histochemical studies indicate that the duodenal glands elaborate a neutral glycoprotein whereas the duct system appears to produce both neutral and acidic elements. Light and electron microscopic studies have shown the duodenal glands to consist of large, pyramidal cells which lie on a distinct basal lamina. Discrete, mottled or pale secretory granules are found in close association both with the apices of the cells and with the Golgi complexes. The ergastoplasm, cisternae of which are dilated and contain amorphous material, is associated with polysomes and, in the supranuclear region, often becomes markedly dilated, forming what appear to be large vacuoles containing fibrillar material. Blebbing of the ergastoplasm results in the formation of several small vesicles, many of which lie in close association with the Golgi network. Direct membrane continuity has been noted between the two elements.     

Prenatal development of the human Brunner's glands

The prenatal development of the human Brunner's glands has been investigated in 23 fetuses from the 10th week of gestation to full-term. At 12 weeks, a few cords of epithelial cells were seen budding from the duodenal mucosa immediately beyond the pyloric sphincter. They represent the initial stage of the development of Brunner's glands. At 16 weeks, Brunner's glands originated as simple tubular downgrowths from the bottoms of the most proximal crypts of the duodenum. The secretory products of the component cells of these primitive tubules contained periodic acid schiff (PAS) positive material which was largely supranuclear in position and resisted digestion by diastase. From 20 weeks to full term, the Brunner's glands developed in a progressive fashion starting in the proximal part of the duodenum near the pyloroduodenal junction. Further tubular downgrowths were added distally, leading to an increase in length of the glandular tissue. The gland showed an increase in size proximally due to elongation and branching of the tubules. At birth, the glandular cells of Brunner's glands resembled those of normal adult in structure and staining reactions. The PAS staining of the cells of the early developed glands (at 12 weeks) was as intense as those of the full-term. The secretory materials of the developed Brunner's glands showed negative reaction with Alcian blue (AB) at pH 2.5 at any stage of development. These results suggest that the mucin secreted by the developed Brunner's glands of human is neutral mucopolysaccharide in nature.     

Postnatal development of the reproductive system in the grey short-tailed opossum, Monodelphis domestica

Postnatal phenotypic sex differentiation has been investigated in a laboratory marsupial, Monodelphis domestica, as part of a larger study to resolve apparent discrepancies between eutherian and marsupial mammals. These include the formation of sex-specific structures in marsupials prior to gonadal differentiation and the retention in both sexes of structures which are sex-specific in eutherians. The time-course and nature of differentiation was investigated in 131 specimens ranging in age from the day of birth to 56 days. Patent wolffian ducts extend to the urogenital sinus in both sexes at birth, while müllerian ducts are identified on day 1 and grow in a cranio-caudal direction to reach the urogenital sinus on day 6. The male müllerian duct shows signs of regression at its cranial end on day 10 and throughout its length on day 12; its lumen has completely disappeared by day 15. By this time the epididymis and vas deferens have developed from the wolffian duct; their histological differentiation occurs between days 26 and 56. Prostatic buds are identifiable in tissue surrounding the male urethra on day 14. In the female, the wolffian duct is larger than the müllerian duct until day 14; thereafter the wolffian duct begins to regress at its cranial end, disappearing by day 17, whereas the müllerian duct begins to enlarge, converging with its fellow at the urogenital sinus by day 19. Lateral vaginae, vaginal culs-de-sac, uteri and oviducts have differentiated from the müllerian ducts by day 25. Gonads of both sexes are elongated in shape at birth, attached along the medial aspect of the large mesonephroi in the abdominal cavity. However, from day 3 onwards the testis becomes more rounded than the ovary. Degeneration of the male mesonephros begins about day 10 and is almost completed by day 19; the female mesonephros is still relatively large at day 14 though it too has almost disappeared by day 19. By postnatal day 13 the abdominal phase of testis descent is underway and the inguinal phase begins at day 15. Testes have reached the scrotal sac by day 24 and achieve their final position at the base of the scrotum by day 28. In summary, postnatal reproductive tract development and gonadal descent has been examined in this important biomedical model, where differentiation of the wolffian and müllerian ducts takes place after gonadal differentiation, according to the normal eutherian pattern.Abbreviations AMH Anti-müllerian hormone - LS Longitudinal section - Md Müllerian duct - PN0 Day of birth - SEM Scanning electron micrograph - SRY Sex-determining region on the Y chromosome - TS Transverse section - Wd Wolffian duct     

Postnatal development of the fore- and hindlimbs in the grey short-tailed opossum,Monodelphis domestica

Marsupials are good experimental animals for developmental studies as their offspring are born at a stage comparable to embryonic stages of eutherian species. The South American opossum, Monodelphis domestica, is particularly useful because of its small size and easy maintenance. This study was carried out to compare development of opossum fore- and hindlimbs during postnatal life, using light microscopy and whole mount alizarin staining. At birth, well-developed mobile forelimbs show cartilage models of bones and myotubular striated muscle fibres. However, hindlimbs are relatively underdeveloped paddle-like outgrowths. Two days later mesodermal condensations form models of the future hindlimb bones and mononucleate myoblast aggregates are present; by 6 days post partum (dpp) the hindlimb has reached a stage of development similar to that of the forelimb at birth. At this stage, periosteal buds have invaded forelimb long bones and nuclei in forelimb muscle fibres have become displaced to the periphery. The 16 dpp hindlimb shows long bones invaded by periosteal buds and closely packed, striated muscle fibres. Epiphyseal plates are now seen in the forelimb long bones and forelimb muscle fibres show mature characteristics. Musculoskeletal development is well correlated with the functional demands of the limbs during postnatal development in the opossum, which provides an excellent model for investigations into the genes and molecules controlling limb development.     

Cytology of eccrine sweat glands in the opossum

Eccrine sweat glands occur only within the glabrous foot and toe-pad skin of the Virginia opossum, Didelphis virginiana, Kerr. Two distinct types of secretory cells are found in the terminal portion of this gland, i.e., dark and clear cells. Thin myoepithelial cells are located between these secretory cells and the outer basal lamina. Histochemical techniques indicate that dark cells contain dense proteinaceous secretory granules. This observation is supported by measuring the refractive index (n) of dark cell granules by interference microscopy. The interferometric properties and certain staining characteristics (acidophilia) displayed by these secretory granules are comparable to those of the stratum corneum layer of opossum glabrous skin. Ultrastructurally, dark cells contain electron-opaque secretory granules and parallel arrays of granular endoplasmic reticulum, resembling those of other protein-secreting cells. Subcutaneous injections of pilocarpine nitrate elicit a secretory response from dark cells consisting of granule extrusion, reduction in cell size, and extreme vacuolization of the cell cytoplasm.     

Signet ring cell carcinoma of Brunner's glands

Signet-cell carcinoma of Brunner's glands and two chronic ulcers of the duodenum were revealed in the course of the histologic examination of the autopsy material from a 76-year-old patient. One of the ulcers penetrated into the pancreas. This case is interesting for rare occurrence of Brunner's glands carcinoma and its combination with chronic duodenum ulcers.     

Postnatal development of adenylate cyclase in rat salivary glands: patterns of hormonal sensitivity.

In order to compare the known morphological changes which occur during the postnatal development of the salivary glands in the rat with alterations in membrane function, we measured adenylate cyclase activity and its responses to sodium fluoride (NaF), norepinephrine, and isoproterenol in salivary gland membranes at various times after birth. In the parotid gland, basal enzyme activity did not change significantly during postnatal life, but fluoride-stimulated activity rose on day 15; A similar marked rise in activity stimulated by norepinephrine (0.02 mM) and isoproterenol (0.03 mM) was noted simultaneously. In the submandibular gland, basal adenylate cyclase activity was higher just after birth than at 25 days of life or in maturity. Fluoride-stimulated activity was 7 times higher than basal activity on day 1, greater than 10 times higher on day 25, and 30 times greater in the adult. The gland was as responsive to norepinephrine and isoproterenol on day 5 as it was on day 25 or in the mature animal, showing a two- to threefold increase over the basal enzyme value at each time point studied. Residual phosphodiesterase activity in the membranes was always negligible. The data demonstrate a time-dependent developmental change in the responsiveness of the parotid gland to norepinephrine and isoproterenol, which corresponds to the time when morphological maturation normally occurs. By contrast, in the submandibular gland, membrane-bound adenylate cyclase is fully developed at the time of birth.     

Brunner's glands of the duckbilled platypus (Ornithorhynchus anatinus)

Brunner's glands in the platypus form a lobulated, glandular collar confined to the submucosa of the most distal portion of the stomach. The glands end immediately proximal to the gastrointestinal junction and excretory ducts empty in the region where the stratified squamous epithelium lining the stomach changes abruptly to the intestinal lining epithelium of the duodenum. An individual gland of Brunner is composed of several elongate lobules drained by intralobular ducts which often join to form a single excretory duct. Light and electron microscopic studies have shown the secretory tubules to be comprised of large, pyramidal cells limited basally by a delicate basal lamina. The ergastoplasm, cisternae of which are dilated and contain amorphous material, is associated with numerous ribosomes. In basal and perinuclear regions intercisternal granules and smooth surfaced vesicles are found. Numerous small vesicles found in supranuclear areas apparently form from the smooth membrane portions of ergastoplasm located adjacent to Golgi complexes. Membrane-bound amorphous granules of varying electron density occupy the apical cytoplasm and show a tendency to coalesce before emptying their contents into the adjacent lumen. The intralobular duct system is lined initially by a columnar epithelium which changes to a simple squamous form before the ducts combine to form a short excretory duct lined by stratified squamous epithelium. The epithelium lining the duct system contains relatively few organelles but appears to be engaged in a limited amount of synthesis and release of secretory material. Histochemical studies indicate that both the secretory tubules and the duct system elaborate a neutral mucopolysaccharide.     

Auditory brainstem response in sheep. Part II: Postnatal development

The auditory brainstem response (ABR) was recorded from 15 chronically instrumented lambs between birth and 7 weeks of age as well as from four adult ewes. Latency changes observed within two days of birth may be related to the dissipation of fluid from the lamb external auditory canal and middle ear cavity. Developmental changes observed in the lambs included an early period of wave latency decrements from 1 to 4 weeks followed by a subsequent increase in wave latencies from 4 to 7 weeks. These changes were significant for the I-IV interwave interval, possibly reflecting the combined effects of increased myelinization and increased neural track length. Responses from 7-week-old lambs were not significantly different from those obtained from the ewes. © 1996 John Wiley & Sons, Inc.     

Relationship between diseases of the pancreas and hyperplasia of Brunner's glands

Summary Examination of 105 duodeno-pancreatectomy specimens showed that 75.7% of the cases of chronic pancreatitis (n = 74) manifested diffuse hyperplasia of Brunner's glands. In pancreatitis involving part of the pancreas in the presence of ducts of the embryonic type (n = 6), in segmental pancreatitis (n = 16), and in pancreatic cancer (n = 23), no significant difference in the thickness of the layer of Brunner's glands was found as compared with normal specimens.There was no statistically significant correlation between the degree of hyperplasia of Brunner's glands and the degree of scarring of the exocrine pancreatic parenchyma. Nor was there any correlation between existence and extent of scarring of the duodenal wall, inflammatory infiltration of the duodenal mucosa, duration of disease, consumption of alcohol and history of gall stones and ulcers in patients with and without hyperplasia of Brunner's glands. Diffuse hyperplasia of the duodenal glands is probably an adaptive reaction to the exocrine insufficiency of the pancreas or the changes in gastric function (hyperacidity, accelerated emptying of the stomach) caused by chronic pancreatitis. A fact which supports this statement is that the inhibitor hormone urogastrone — an inhibitor of gastric acid secretion — is formed in Brunner's glands. The question is also discussed whether chronic pancreatitis and hyperplasia of Brunner's glands might not also develop simultaneously in the presence of disturbances of the gastrointestinal hormones, themselves either primary or due to alcohol consumption.     

Postnatal development of the submaxillary salivary and external orbital lacrimal glands of white rats

Summary The object of study was the character of the growth of the submaxillary salivary and the external orbital glands. The weight of the glands, the size of their lobules, acini, nuclei, and the mitotic activity of the secretory cells were determined. It was found that up to the age of 40 days the increase in the gland weight is due mainly to the formation of new acini; the latter takes place by proliferation of the cells of the terminal portions. After 40 days, the formation of new terminal portions occurs in a slight degree. The growth of the gland by the age of 75 days and later is due exclusively to an increase in the size of all structural components of the organ, and in the submaxillary gland also to the appearance and growth of convoluted ducts.(Presented by Active Member of the Academy of Medical Sciences of the USSR N. N. Zhukov-Verezhnikov) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 61, No. 5, pp. 113–115, May, 1966     

Histochemical factors influencing the sulfation of the mucosubstances of the Brunner's glands of the human duodenum.

The mucopolysaccharides of the human Brunner's glands were sulfated by sulfuric acid diluted with acetic anhydride or nitrobenzene (1:50) in 5 min. They were recognized by toluidine blue at a pH of less than 1 by exhibiting a red-violet or violet-red metachromasia. The sulfated radicals were removed by methanol or butanol with HCl, H2SO4, Na or NaOH, aqueous Ba(OH)2 at 60 degrees C, or by acetic anhydride, acetyl chloride, benzoyl chloride, or bromine water at 25 degrees C. The carbohydrates were altered so that sulfation was prevented by prior treatment with aqueous Ba(OH)2, or by acetic anhydride with pyridine at 60 degrees C and by acetyl chloride and by bromine water at 25 degrees C. Periodic acid Schiff staining was prevented by sulfation with a nitrobenzene: H2SO4 mixture but not by an acetic anhydride: H2SO4 combination in 1 h suggesting an additional sulfate radical at hydroxyl sites 1 or 2. Brunner's glands contain a large amount of a neutral mucopolysaccharide and can be used as a model for testing a large number of chemical and blockage reactions. In nearly all instances, Brunner's glands reacted more like pyloric glands than duodenal goblet cells.     

Postnatal development of neurogenic inflammation in the rat.

We have studied the development in the rat of neurogenic inflammatory mechanisms that mediate cutaneous plasma extravasation. At birth and at postnatal day 10, intradermal injection of substance P, histamine, and bradykinin produced no significant plasma extravasation. At day 13 through adulthood (days 42-49), all test agents produced significant plasma extravasation which increased with increasing age. In the adult rat, pretreatment with 6-hydroxydopamine, to eliminate sympathetic postganglionic nerve terminals, attenuated the plasma extravasation elicited by substance P, histamine and bradykinin. The possible role of the sympathetic postganglionic neuron in the age-dependent changes in neurogenic inflammation is discussed.     

Carbohydrate histochemistry of the opossum submandibular and major sublingual glands

Submandibular and major sublingual salivary glands of the opossum contain histochemically demonstrable neutral mucosubstances, nonsulfated acid mucosubstances and sulfomucins. Sialomucins could not be demonstrated conclusively with the methods used in this study. Special serous cells of the opossum submandibular gland contained low concentrations of acidic mucosubstances but no appreciable concentration of neutral mucosubstances was seen. Sulfomucins were not observed in special serous cells. The mucous tubules of the submandibular gland contained high concentrations of neutral mucosubstances. No appreciable acidic mucosubstance was demonstrated in the submandibular gland mucous tubules. Unlike the mucous tubules of the submandibular gland, the major sublingual gland mucous tubules contained high concentrations of both neutral and acidic mucosubstances. The mucous tubules often contained sulfomucin-positive cells interspersed among cells that contained high concentrations of non-sulfated acidic mucosubstance. Marked staining of sulfated acidic mucosubstance was seen only in the major sublingual gland, in both the mucous tubules and in the seromucous demilunes. The seromucous demilunes contained both sulfated and non-sulfated acidic mucosubstances.