Lateral Pouches Research Articles

Oogenesis inPentastomida

During oogenesis in Pentastomida the oocytes wander from a germinal zone in the mid-dorsal ovarial wall to the lateral pouches of the ovary. The growth phases are initiated during that migration, but not until the lateral pouches are reached does the oocyte grow considerably. A Balbiani body consisting of numerous mitochondria, and various vacuolar inclusions are formed, and at the same time the oocyte bulges out into the hemocoel. Some wall cells form a stalk and cover part of the oocyte towards the hemocoel. During later stages of oocyte growth they withdraw, and the oocyte is separated from the hemocoel only by an extremely thin basement membrane. It seems that the young oocytes obtain nourishment from the ovarial lumen by way of the wall cells. The contents of the lumen in its turn seems to be derived from the hemocoel through the activity of mid-ventral secretory cells. The older oocytes are provided with numerous microvilli, and material for the growth of the oocytes must be taken up directly from the hemocoel. A very dense egg shell is secreted by the oocyte. In nearly mature oocytes the microvilli withdraw from penetrating this shell, and a mucopolysaccharide layer is formed beneath the shell. The mature oocytes in some unknown way make their way to the ovarial lumen whence they are transported to the uterus.

Reproductive organs ofGryllodes sigillatus(Walker) (Orthoptera: Gryllidae)

Summary The reproductive organs of the male and female Gryllodes sigillatus, together with their associated muscles, are described in detail. The male reproductive organs are characterized by the presence of the accessory gland tubules and the absence of sperm vesicles. The presence of a pair of lateral pouches on the genital chamber and a chitinous bursa copulatrix at the posterior end of the spermathecal duct are peculiar features of the female reproductive organs. The testes and the ovaries are attached by the testicular and ovariolar ligaments respectively to the tergum of the first abdominal segment.

Feeding and gut physiology in Acanthopleura spinigera (Mollusca)

The morphology and histology of the alimentary canal of the rock chiton Acanthopleura spinigera are described and the ability of regions of the gut to digest specific substrates investigated. The oesophagus is produced into a pair of thin‐walled lateral pouches, the salivary glands or “sugar glands” which empty into the stomach. Folds of the capacious stomach are almost obscured by the large digestive gland over which is coiled the intestine. Histologically the gut consists of an outer layer of connective tissue, an inner muscular layer and a ciliated epithelium which varies in thickness from one region to the next. Proteases are most active in the stomach, digestive gland and anterior intestine at pH 6·5 and in the posterior intestine at pH 7·5‐8·5. The digestion of lipoidal substance was greatest in the stomach and digestive gland and least in anterior intestine. There was little increase in the amount of digestion product obtained after 20 hours incubation. All regions of the alimentary canal and salivary gland were capable of digesting carbohydrates except that many low molecular weight carbohydrates were digested by salivary gland extracts only. The amylases were most active at pH 6–6·5. It is concluded that digestive enzymes are distributed throughout the intestinal tract but the amount of enzyme present varies from region to region, and is greatest just after feeding.

On understanding the organisation of the retinal receptor synapses

Summary With the appropriate techniques the retinal receptor (first order) synapse is shown to contain plain synaptic vesicles, complex (coated) vesicles and shell fragments. The complex vesicles appear to be budded off exclusively from that zone of the presynaptic membrane that lines the pouches that lie one on each side of the synaptic ribbon. No complex vesicles are ever included with the synaptic vesicles that form a halo round the ribbon. The vesicles of the outermost row (or two rows) of ribbon vesicles lie in close contact with the presynaptic membrane and that part of the postsynaptic (horizontal cell) membrane opposite this contact zone (presumably where the transmitter is released) has a rectangular strip of ‘postsynaptic thickening’ along its cytoplasmic surface. A comparison is made between the morphology of these synapses and those that occur in the brain. Both types have plain synaptic vesicles and complex vesicles and shell fragments, suggesting that in both cases the synaptic vesicles have arisen from the complex vesicles. The latter, in the brain synapse, have formed from the lateral walls of the presynaptic bags whereas in the retinal synapses their formation is restricted to the lateral pouches. Empty shells and shell fragments (confirmed by electron stereoscopy) are restricted to the presynaptic cytoplasm bordering the pouches. In the brain synapse the dense projections may play a part in guiding the synaptic vesicles to the presynaptic membrane over an area: in the retinal synapse the ribbon may play this role and the vesicles are guided to a narrow strip of presynaptic membrane.

On the morphology, feeding, and behavior of Magelona sp.

1. Observations were made on the morphology, especially that of the circulatory system, the feeding, and the behavior of the polychaetous annelid Magelona sp. from the vicinity of Woods Hole, Massachusetts. 2. Features of particular interest related to the circulatory system include an anterior dorsal vessel which is divided into a series of chambers set apart by valves. The chambers undergo a precisely timed filling and emptying and pass blood forward to a heavily muscularized portion of the dorsal vessel whose contractions provide the primary pressure for movement of the blood. Segmentally arranged valves were noted in the posterior part of the dorsal vessel. 3. Burrowing is accomplished by the insertion of the prostomium into the substratum and the subsequent extrusion of the proboscis. This extrusion is brought about primarily by the hydraulic pressure of blood which has been expelled from the anterior region of the body by the contraction of all anterior somatic muscles except the proboscidial retractors. 4. Magelona sp. utilizes the papillae of its paired prostomial tentacles in feeding. Food material adheres to distal papillae and is transferred to more proximal papillae when a loop is formed by the tentacle; by repetition of this activity, the food material is passed stepwise toward the mouth. 5. Observations were also made on lateral organs, which may prove to be vibration receptors, and on so-called lateral pouches, whose function is unknown.

The evolution of arthropodan locomotory mechanisms. Part 8. Functional requirements and body design in Chilopoda, together with a comparative account of their skeleto-muscular systems and an Appendix on a comparison between burrowing forces of annelids an

The evolution of arthropodan locomotory mechanisms. Part 8. Functional requirements and body design in Chilopoda, together with a comparative account of their skeleto-muscular systems and an Appendix on a comparison between burrowing forces of annelids an

DEVELOPMENT OF THE AMPHIBIAN EAR RUDIMENT IN EXPLANTS

1. Two series of operations were performed on larvae of Taricha rivularis, T. torosa, Ambystoma maculatum, A. tigrinum and Rana sylvatica. In the E Series, a piece of ectoderm with attached ear rudiment was excised. and the mesendoderm and some, if not all, of the mesectoderm were removed. In the EM Series, mesendoderm and mesectoderm were included with the ear rudiment and ectoderm. These excised tissues were cultured, together with the donor larvae, in sterile Holtfreter's solution for varying lengths of time and, in most cases, at 15° or 16° C.2. Study of serial sections of the explants showed that time ear rudiments of T. rivularis, T. torosa, A. maculatum and R. sylvatica were capable of independent development and differentiation up to the stage when the auditory vesicle possesses a distinct endolymphatic duct and sensory epithelium. This corresponds to Stage 40 in the salamanders and Stage 22 in the frog. In a few cases, there was some indication of the beginning of formation of a lateral pouch and...

ANATOMY OF THE SEED OF CONVOLVULUS ARVENSIS

Sripleng, Aksorn, (Kasetsart U., Bangkok, Thailand), and Frank H. Smith. Anatomy of the seed of Convolvulus arvensis. Amer. Jour. Bot. 47(5) : 386—392. Illus. 1960.–The anatropous ovule has a small, ephemeral nucellus covered by a massive integument. Shortly after fertilization, a lateral pouch develops from the upper portion of the embryo sac toward the dorsal side of the ovule and then downward. This leaves a partial integumentary septum in the base of the seed. The cellular endosperm is mostly absorbed by the embryo. Two—6 cell layers persist on all sides of the seed except below the cotyledons on the dorsal side where larger amounts persist. Over most of the seed the dermatogen develops into an epidermis that consists in part of groups of thick‐walled elongate cells that produce the papillose appearance of the mature seed. The cells beneath the dermatogen divide periclinally and form 2 layers. The outer layer undergoes anticlinal divisions and differentiates a subepidermal layer of small, rectangular, thick‐walled cells that become lightly lignified and suberized. The cells of the inner layer undergo some anticinal and periclinal divisions, elongate and differentiate as palisade sclerenchyma. The inner layers of the integument consist of parenchyma cells that are crushed and partially absorbed at maturity. The pad on the basal end of the seed, between the hilum and micropyle, is derived from a multiple epidermis that is differentiated into several layers of rectangular cells and a layer of palisade sclerenchyma. The subepidermal and palisade layers found over other parts of the seed dip beneath the pad.

POUCHES OF THE PHARYNX AND ESOPHAGUS

My object in this paper is to review the literature on diverticula of the pharynx and esophagus, to mention their probable mode of development, to call attention to the frequency of their occurrence, to discuss their diagnosis and differential diagnosis, and to add an additional twenty-three cases as studied in the Esophageal Clinic at the Massachusetts Eye and Ear Infirmary. A diverticulum may be defined as a blind pouch that has developed from a viscus or normal canal and may consist of one or more layers of the part involved. BRANCHIAL CLEFT ANOMALIES Branchial cleft anomalies must be mentioned in this paper to complete all the pouch formations in the pharynx. The only congenital diverticula in this region are those of branchial cleft origin. Only rarely do they cause obstruction and contain food. In one patient examined there were two lateral pharyngeal pouches and one posterior, the two lateral pouches

Notes on the Larvae of Moniliformis moniliformis (Brems.) Found in African Cockroaches

30 cysts which were collected by Dr. J. W. S. Macfie of Accra, Gold Coast, West Africa, from the abdominal cavities of 2 cockroaches (Periplaneta americana). Among these cysts were found 8 or 9 gravid female specimens of Oxyuris blattae-orientalis Hammersch., 1847, recognized by the esophagus possessing a lateral pouch. Travassos (1917) splits up the family Gigantorhynchidae, Hamann, 1892, into 2 sub-families, viz., Gigantorhynchinae, Travassos, 1915, and Prosthenorchinae, Travassos, 1915. The sub-family Gigantorhynchinae contains 5 genera, 1 of which is Moniliformis, characterized by the possession of numerous small hooks. There are 2 species in the genus, viz., M. moniliformis and M. cestodiformis (v. Linstow, 1904)

A new Species of Enteropneusta, Ptychodera pelsarti*, from the Abrolhos Islands.

It will be advisable perhaps to add, in the form of a summary, a short diagnosis of the characters of the species Ptychodera pelsarti. Ptychodera Pelsarti, n. sp.—Moderately large form, average size of preserved specimens 50–60 mm. (considerable contraction had taken place). Proboscis cavity with longitudinal muscles gathered into distinct radially arranged bundles. Neck of proboscis with a distinct well-developed but unlobulated “racemose” organ. Ventral proboscis, caecum, and “racemose” organ compressed laterally. Cornua of nuchal skeleton very long and reaching posterior half of collar, body of skeleton with characteristic shape. Two proboscis pores. Stomochord with well-developed lateral pouches. (Esophageal region of pharynx predominates over the branchial. Collar nerve-cord with continuous lumen and usually with three dorsal roots. Locality: Polsart Island, Abrolhos Islands, West Coast of Australia.

On the peculiarities that distinguish the manatee of the West Indies from the dugong of the East Indian seas

The following are the principal differences pointed out by Sir Everard Home as characterizing the Manatee of the West Indies from that species of the Dugong, lately described to the Society, from Sumatra. It differs externally in the shape of the tail, in hav­ing neither tusks nor nails, and also in the form of its snout. The teeth differ in number; and though the general form of the skeleton is similar, there are fewer vertebræ. The stomach differs in the shape of the solid glandular part, and of the lateral pouches, but both animals feed upon fuci. The forms of the teeth, however, in these two species are totally different, which shows, says the author, how inefficient a mode of classing animals is furnished by the appearance of the teeth.