Osmoregulatory role of the brood pouch in the euryhaline Gulf pipefish, Syngnathus scovelli

Many species of pipefish exhibit a reversal of parental roles, in which females insert eggs into the brood pouch of the male where they are incubated until the end of embryonic development. While the significance of the male brood pouch has been examined for over a century, the role of the pouch is still unclear. One possible function is to aid in osmoregulation by buffering embryos from the external environment. To investigate this role, the euryhaline Gulf pipefish, Syngnathus scovelli, was collected and maintained in either a low salinity or a saltwater environment. Changes in plasma and pouch fluid osmolality and morphological changes of the pouch were examined. Brood pouch fluid was similar to male plasma during the early and late stages of the brooding period for low salinity males, but was significantly hyperosmotic during the middle of the brooding period. In saltwater males, brood pouch fluid was similar to plasma during early brooding, but became hyperosmotic as brood time progressed. The brood pouch epithelium of both low salinity and saltwater males contained mitochondria-rich cells. In early brooding saltwater males these cells contained an apical opening into the pouch lumen. Osmotic and morphological differences observed suggest that the brood pouch plays an active role in regulating osmotic concentration of the pouch fluid. Additionally, pouch fluid concentration may be regulated more during early stages of embryonic development.     

Birth in marsupials

Birth is an event that allows the relatively immature marsupial to move from the internal environment of the uterus to the external environment of the pouch. The newborn marsupial passes down from the uterus to the urogenital sinus and then makes its way to the pouch and attaches to the teat at a very early stage of development. From the studies available, there appear to be three methods used by the newborn to move from the uterus to the pouch. In marsupials with a forward pouch such as the red kangaroo, tammar wallaby and the brushtail possum, the mother positions her urogenital sinus below the pouch and the newborn climb upward towards the pouch. The young climb with a swimming motion, moving the head from side-to-side and use the forearms in alternate strokes. In the bandicoot with a backward facing pouch, the mother positions the urogenital sinus above the pouch and the young slither down into the pouch. The young do not have a definite crawl, as seen with the macropodids and possum. The third method of birth has been observed in the marsupials without a definite pouch that have a mammary region that develops as the young grow in size. This type of pouch is observed in the dasyurids. The mother was noted to stand on four legs with her hips raised so that the urogenital sinus was above the pouch and the newborn young crawled downwards from the sinus to the pouch. In all species, birth was completed in 2–4 min.     

The phylogenetic distribution and morphological variation of the ‘pouch’ in female snakes

Siegel D.S., Miralles A, Trauth S.E. and Aldridge R.D. 2011. The phylogenetic distribution and morphological variation of the ‘pouch’ in female snakes. —Acta Zoologica (Stockholm) 93 : 400–408. The urodaeum of female snakes is a chamber that receives the oviducts, urinary ducts, and intestine. Previous studies have indicated that a derived region of unknown function persists between the urodaeum and oviducts in some snakes of the Colubroides. This structure was recently termed the ‘pouch’; however, it is also commonly referred to as the vaginal pouch. A broad sampling of female snakes revealed that the pouch evolved once on the branch leading to Colubroides. The presence of the pouch in Colubroides is not unambiguous, as this feature was lost in some members of the Atractaspididae and Lamprophiidae. Variation was also observed in pouch morphology between taxa of the Colubroides. Variation included the following: (1) whether the pouch was bifurcated and if so, were the arms of the pouch separated caudally, (2) whether separated pouch arms were split by a caudal bifurcation of the urodaeum or through medial septa of the pouch arms, and (3) the absence or presence of oviducal papillae invading the cranial/lateral extremity of the pouch. The variation in pouch morphology observed does not appear to be correlated with the evolutionary history of Colubroides and polymorphism within families is common.     

Microflora of the pouch of the koala (Phascolarctos cinereus).

Microflora of the pouch epithelium of 17 female koalas (Phascolarctos cinereus) were examined in relation to their current reproductive status and recent reproductive history. No microbial growth was observed in pouch swabs from 13 of 17 (76%) koalas, including four females without young, seven with pouch young and two with back young (i.e. permanently emerged from the pouch). Growth of bacteria or yeasts was observed in pouch swabs from four koalas, each of which had experienced mortality of its pouch young during the current breeding season. Seven species of microorganisms were isolated, including Pseudomonas aeruginosa, Serratia marcescens and Enterococcus faecalis. Based on the absence of microflora in the majority of females examined, we propose that the pouch epithelium normally provides a hostile environment for microbial colonization.     

Immunocytochemical detection of mitochondria-rich cells in the brood pouch epithelium of the pipefish, Syngnathus schlegeli : structural comparison with mitochondria-rich cells in the gills and larval epidermis

The brood pouch of the male pipefish (Syngnathus schlegeli) is a ventral organ located on the tail, with the anterior region closely associated with the genital pore. The embryos in the pouch are attached to highly vascularized placenta-like tissue which seals the pouch folds from inside during incubation. The epithelium of the placenta-like tissue consists of mitochondria-rich cells (MRCs) and pavement cells. Differences in MRC morphology in the brood pouch epithelium, the gills and the larval epidermis of the pipefish were examined by light and electron microscopy. Transmission electron microscopy revealed that the MRCs in the brood pouch and the gills shared common characteristics: the presence of numerous mitochondria packed among a well-developed tubular system and the close association of the basal parts with the capillaries running underneath the epithelia. The size of the apical opening of the elongate, flask-shaped brood pouch MRC was about one-tenth that of the apical pit of the gill MRC. The gill and larval epidermal MRCs formed a multicellular complex, in contrast to solitary brood pouch MRCs. The brood pouch MRCs were intensively stained by immunocytochemistry with an antiserum specific for Na⁺,K⁺-ATPase. The Na⁺ concentrations in the brood pouch were maintained near those in the serum rather than seawater during incubation. We conclude that the brood pouch MRCs function as an ion-transporting cell, absorbing ions from the brood pouch lumen, perhaps to protect the embryos from the hyperosmotic environment.     

The development of thermoregulation in the rat kangaroo,Potorous tridactylus

• 1.1. The young were first seen out of the pouch on day 103.2 ±2.0 post-partum, and were permanently out of the pouch on day 119.7 ± 1.6, several days prior to the birth of the next young on day 122.8 ± 2.2.
• 2.2. The average mother's pouch temperature and the young's rectal temperature while in the pouch showed similar ranges—however, further analysis demonstrated that the pouch temperature decreased towards the end of lactation.
• 3.3. The difference in rectal temperature of the young in the pouch from 90–107 days to 108–123 days was 0.01 ± 0.34°C, whereas the mother's pouch temperature decreased 0.68 ± 0.37°C.
• 4.4. The results of this study suggests that curiosity and the need for solid food are the primary reasons for the young leaving the pouch and temperature does not play a primary role in the evacuation of the pouch.

     

Does motilin control interdigestive pepsin secretion in the dog?

Pepsin output in the Heidenhain pouch, plasma motilin concentration, and contractile activity in the pouch and the main stomach were investigated in five dogs. During the interdigestive state, the pepsin output was significantly increased with a cyclic increase in contractile activity in both the pouch and main stomach at approximately 100-min intervals. The plasma immunoreactive motilin (IRM) concentration fluctuated during the interdigestive state, and, peaks of IRM concentration coincided with the maximum pepsin secretory activity. Exogenous administration of motilin (0.5 micrograms/kg-hr) increased contractile activity in the main stomach and pouch quite similar to the natural interdigestive migrating contractions (IMC), and increased pepsin output significantly. Atropine pre-treatment suppressed the naturally-occurring and motilin-induced pepsin output and contractions in the pouch. It is concluded that pepsin output and contractions in the Heidenhain pouch increase in close association with the IMC in the main stomach during the interdigestive state and these cyclic motor and secretory events in the vagally denervated fundic pouch are most likely regulated by motilin through the intramural cholinergic pathway.     

Inhibition by dexamethasone of histamine production in allergic inflammation in rats.

In an allergic inflammation model of air pouch type in rats, histamine level in the pouch fluid and histidine decarboxylase activity of pouch wall tissues in the postanaphylaxis phase were increased. Although treatment with dexamethasone failed to inhibit histamine release from mast cells in the anaphylaxis phase, histamine production in the postanaphylaxis phase was inhibited dose dependently. Histamine production-increasing activity in the pouch fluid collected 8 h after the Ag challenge, which was estimated by an activity to stimulate histamine production by bone marrow cells, was decreased by the administration of dexamethasone at the time of the Ag challenge. The addition of steroidal antiinflammatory drugs, dexamethasone, prednisolone, or hydrocortisone, into the incubation medium inhibited the pouch fluid-induced histamine production by bone marrow cells. Hydrocortisone mesylate antagonized the inhibitory effect of dexamethasone on histamine production by bone marrow cells. However, hydrocortisone mesylate failed to recover the decrease in histamine production-increasing activity of the pouch fluid collected from dexamethasone-treated rats. In addition, the dialyzed sample of pouch fluid obtained from dexamethasone-treated nonsensitized rats did not reduce the stimulated histamine production by the pouch fluid sample obtained from the sensitized rats. However, increase in histamine production of bone marrow cells stimulated by the pouch fluid was not inhibited by cyclosporin A that inhibited histamine production induced by Con A. This observation indicates that the pouch fluid has no effect to induce production of the histamine production-increasing factor by bone marrow cells. Consequently, it is suggested that dexamethasone inhibits not only the production of histamine production-increasing factor but also the response of histamine-producing cells to this factor.     

Ultrastructure of the cirrus pouch of Cylindrotaenia hickmani (Jones, 1985) (Cestoda, Nematotaeniidae)

The cirrus pouch of Cylindrotaenia hickmani was examined by transmission electron microscopy. The cirrus pouch is a complex organ consisting of muscular, nervous and epithelial tissues. Muscles forming the cirrus pouch wall contain large myocytons that merge with myofibrils. Muscles supplying the gonadoducts within the pouch consist of small myocytons which are connected to associated myofibrils by elongate processes. Discrete neuromuscular junctions are commonly seen in both muscles. Two cells, thought to be neurons, are present in the pouch. The abundance of nervous tissue in the pouch is suggestive of a high level of neural control of the activity of that organ. The cirrus is lined by filamentous, hook-like and blade-like microtriches. Ciliated sensory receptors are found among the microtriches lining the cirrus. Epithelial cytons associated with proximal regions of the cirrus produce a material which is secreted from the syncytial cytoplasm of the cirrus. Intercellular junctions, resembling gap junctions, are common among the cells associated with the cirrus. The complexity of the cirrus pouch of C. hickmani suggests that this organ may prove valuable for studies on neuromuscular physiology and cellular interactions in cestodes.     

Subcutaneous air pouches in the Marabou stork (Leptoptios curmeniferus)

Dorsal and ventral subcutaneous, dilatable air pouches play a part in the social life of the Marabou stork. Inflation of the ventral pouch indicates the dominance of an individual over its neighbours whilst inflation of the dorsal pouch indicates apprehension. Both are inflated simultaneously during courtship. Air enters the ventral pouch by a complicated route within the left orbit. The dorsal pouch most probably receives air by way of the first anterior dorsal secondary bronchus of the lung and the cervical air sac.     

The reproductive biology of Bennett's wallaby (Macropus rufogriseus rufogriseus) ranging free at Whipsnade Park

Between August 1981 and October 1982, 76 female and 50 male of the estimated 400 Bennett's wallabies at Whipsnade were caught and examined. Sixty-four of the adult females inspected (84%) were carrying pouch young. A small captive breeding colony was established in the laboratory. Weight and growth curves were established for captive born pouch young and these curves were used to determine the approximate age of pouch young examined at Whipsnade. Eighty-four percent of births occurred in August and September, exactly a six month difference from births reported for this species in Tasmania. The mean length of pouch life of wild living wallabies was 247 days with a range of185–284 days. Young wallabies were observed accompanying their mothers for up to 204 days after emerging permanently from the pouch. Sixty-three percent of young vacated the pouch in May. Sixty-three percent of the total (104) pouch young examined in the course of this study, from animals caught or from post mortem records, were male, but teat selection showed a random distribution. The gestation period from removal of pouch young to day of birth was 27·3 days. The Bennett's wallaby showed precise seasonal breeding with embryonic diapause that may extend for up to 11 months.     

Comparison of three types of continent urinary diversions in a single center

The results including the complication and continence rates for 3 types of continent urinary diversion were evaluated. From 1992 to 1998 we performed 58 continent urinary diversions after radical cystectomy for invasive transitional cell carcinoma (TCC) of the urinary bladder. All three types of continent diversions and ileal loop procedures were discussed and patient preferences were determined. The patient preference rate for continent urinary diversion was 96.6%, and half of these patients wanted to be completely dry. Mean age of the patients was 58.2 years. Of the 58 patients, 9 (15.5%) had a Kock pouch, 15 (25.8%) had a Kock neobladder and 34 (58.6%) had sigmoidorectal pouch (Mainz-II pouch). Early and late complication rates of the three different continent diversions were evaluated. The number of complications, such as urine leakage, pyelonephritis, hydronephrosis, reflux and stone formation, were similar in all three types of diversions. Two (5.9%) Mainz pouch II patients who had stopped oral alkalinization demonstrated severe hyperchloremic acidosis. Spontaneous pouch rupture occurred in 1 of the Kock pouches. Reoperation rates were higher with the Kock pouch and Kock neobladder cases. Daytime continence rates for the Kock pouch, Kock neobladder and Mainz II pouch were 77.7%, 86.7% and 100% respectively. Even though complete dryness may not be achieved in every patient, orthotopic bladder substitution appears to be the best choice after radical cystectomy. Although it carries the risk of life-long oral alkalinization therapy, the Mainz pouch II is associated with an excellent continence rate and may be a good alternative for patients who desire to be dry.     

Temperature gradient from the urogenital sinus to the pouch in the pregnant marsupial quoll, Dasyurus hallucatus

1. The mechanisms utilised by the newborn quoll to move from the uterus to the teat within the pouch are unknown. The ability to sense gravity and odour have been suggested and it is possible that temperature may also assist the young in this migration.

2. An increasing temperature gradient was observed from the sinus at 28.98 °C increasing to 29.38 °C on the skin between the sinus and the pouch and further increasing to 30.96 °C within the pouch. This temperature gradient was not as apparent during lactation.

3. Hairs may also play an important role in allowing the newborn to leave the gelatinous material emanating from the uterus and travel to the pouch. The hairs form a tunnel between the sinus and the pouch and may assist the young in the moving from uterus to the pouch.     

Developmental changes in proliferative activity of cells of the murine Rathke's pouch

Summary To clarify proliferative activity in the cells of the Rathke's pouch of the rat, we studied the labeling index using bromodeoxyuridine-immunohistochemistry. Rat fetuses were removed 1 h after transplacental injection of bromodeoxyuridine on day 11.5–21.5 of gestation, and were subsequently used to examine cellular proliferation. Although the labeling index within the Rathke's pouch was 30% on day 12.5, it decreased with development and by day 18.5 of gestation had a value of about 5%. The labeling index within Rathke's pouch was not homogeneous throughout the entire pouch, but tended to be higher in regions where cells were more densely packed. This heterogeneous pattern of distribution of labeling index values continued until day 15. On that day, immunoreactive ACTH cells first appeared in the region where the labeling index was low. From day 17 of gestation, the uneven distribution of the labeling index became vague and, simultaneously, the distribution of ACTH cells became homogeneous throughout the pouch. It was concluded that proliferation of the epithelium of Rathke's pouch is heavily involved in the growth of the pouch until at least the appearance of ACTH cells.     

酸化胃窦对组织胺性胃酸分泌的抑制作用

用具有胃窦小胃、胃体小胃和胃肠吻合制备的狗做慢性实验,观察酸化胃窦粘膜对胃体小胃组织胺性胃酸分泌的抑制作用。一次皮下注射磷酸组织胺0.04mg/kg 体重,可使胃体小胃的胃酸分泌达到最大分泌量;在3—4h 内,每隔15分钟皮下注射磷酸组织胺0.01mg/kg体重,从第四次注射以后,即可使胃体小胃的酸分泌持续稳定在高水平。用0.1mol/L 盐酸灌注胃窦小胃,上述两种组织胺性胃酸分泌均受到抑制,而用生理盐水灌注则无影响。由此得出结论:酸化幽门部粘膜能抑制组织胺性胃酸分泌。由于这种抑制现象出现的潜伏期较长(15min 以上),作用持续时间较久(超过2h),提示酸化幽门部粘膜对组织胺性胃酸分泌的抑制作用,可能是通过某种抑制性体液因素实现的。     

Dynamics of the inflammatory process caused by carrageenin administration during experimental therapy

Carrageenan is shown to cause acute inflammation in mucous membrane of hamster cheek pouch and rat hind foot. Rutin has no effect on the pathological process in the cheek pouch, and arrests the first phase of inflammation in the foot. Esculamine has a therapeutic effect on both phases of inflammatory reaction in the cheek pouch and foot.     

The Ultrastructure of Brood Pouch Formation in Tokophrya infusionum

SYNOPSIS Asexual reproduction in Tokophrya infusionum is by internal budding, whereby a ciliated, motile embryo is formed inside the sessile, non-ciliated parent in a specialized structure, the brood pouch. The process of embryogenesis and brood pouch formation was studied with the electron microscope using synchronized cultures. Reproduction begins with invagination of the pellicle and plasma membrane in the apical region of the adult. Early invagination is characterized by the presence of numerous microtubules beneath the plasma membrane or epiplasmic layer of the invaginating membranes. These microtubules apparently are important in formation of the brood pouch for colchicine blocks embryogenesis during the early stages. When the embryo is completed, it is ejected from the brood pouch thru the birth pore, an opening which is the site of the initial invagination and is present thruout embryogenesis. Theories of brood pouch formation are reviewed and discussed in light of the present investigation.     

Functional significance of the male brood pouch in the reproductive strategies of pipefishes and seahorses: a morphological and ultrastructural comparative study on three anatomically different pouches

The morphological organization of the male brood pouch skin of three different species of syngnathids ( Nerophis ophidion, Syngnathus abaster and Hippocampus hippocampus ), investigated using light and electron microscopy, showed that each pouch had a skin with a different ultrastructure. This reflected different relationships between the paternal body and the developing embryos. In N. ophidion , the bilayered epidermis of the pouch consisted mainly of pavement cells (filament-containing cells) typical of fish skin. In S. abaster , pavement cells were interspersed with many mitochondria-rich cells. These cells varied in number during the different functional stages of the pouch and died by apoptosis after the breeding period. Modified secretory 'flame cone cells' rich in vesicles and granules characterized the epidermis of H. hippocampus . Although there were specific differences, the vascularized dermis was the only feature common to all three types of pouch. These findings suggest that the brood pouch in Syngnathidae has different functions, which may be related to the different reproductive strategies and ecology of each species.     

The Structure of the Gular Pouch of Mature Males of the Lamprey Geotria australis

Males of the southern hemisphere lamprey Geotria australis develop a large gular pouch during sexual maturation. The wall of this pouch contains (I) an epidermis comprising typical lamprey epidermal cells, (II) a thick dermis consisting of layers of collagen fibres, with intervening oxytalan fibres, and a vascular network, and (III) a hypodermis. The hypodermis contains active fibroblasts embedded in an extracellular matrix, comprising collagen fibrils, some of which form dense bundles, together with oxytalan fibres and an amorphous material that contains glycosaminoglycans. The hypodermis also contains arteries, which are innervated and confluent with a large anastomosing system of sinuses. Since these sinuses open at intervals into the large central cavity of the pouch, it is proposed that, at maturity, they discharge blood into the central lumen of the pouch, thereby causing the pouch to become distended. The degree of such distension would be regulated by the limited elasticity of the dermal collagen fibres. The dermis is thickest in those regions where the pouch is most susceptible to abrasion. The Weibel–Palade bodies, which are abundant in the sinus endothelia, may facilitate tissue repair where neccessary. The gular pouch is thus a specialised structure, which may play a role in courtship or the spawning act.     

Morphology and ultrastructure of a specialized bacterial pouch in the digestive tract of Tetraponera ants (Formicidae, Pseudomyrmecinae)

The digestive tract in workers of some species of the pseudomyrmecine ant genus Tetraponera is characterized by a conspicuous pear-shaped diverticulum at the transition between the midgut and the intestine, that so far has not been found in any other ant species. As this organ is filled with a mass of bacteria, we propose to designate it as a bacterial pouch. Its distal wall is formed by a thin ectodermal epithelium, through which tens of tracheal branches penetrate into the bacterial mass that fills the pouch lumen. The proximal wall, in contrast, is formed by a cylindrical epithelium with a conspicuous microvillar differentiation of the apical cell membrane, but without a cuticular lining. The contact region between both epithelia occurs as a complex fold surrounding the pouch like a belt. The Malpighian tubules open into the pouch through the cylindrical epithelium adjacent to the belt fold. The functional significance of the bacterial pouch remains unknown, although the abundant presence of bacteria may indicate a symbiotic function. The conspicuous tracheolar supply illustrates the metabolic activity in the pouch, while the microvillar differentiation of the cylindrical epithelium may be interpreted in the uptake of metabolites from the pouch lumen.