Morphogenesis of silkmoth chorion: Initial framework formation and its relation to synthesis of specific proteins

Morphogenesis of the silkmoth eggshell is described at the ultrastructural level. Four zones are each assembled in a distinct manner and during a distinct developmental period: the innermost vitelline membrane and the adjacent trabecular layer appear consecutively, followed by a thin sieve layer, and a thick, lamellate chorion. Once formed, the sieve layer remains attached to microvilli, and thus all components which assemble into lamellae must pass through the sieve layer. Initially, lamellogenesis (and sieve layer formation) occurs in patches overlying trabeculae. Lamellae quickly fuse and new ones are added, presumably by apposition. Distinct types of lamellae seen in the mature chorion are already distinguishable in early lamellogenesis. The final lamellar number is attained before the developing chorion is one-half its final thickness or one-fifth its final dry weight. The early lamellae constitute a framework which is subsequently modified through expansion and densification. Proteins which may represent components of various parts of the eggshell have been identified on the basis of their timing of synthesis, relative amino acid compositions, and spatial distributions within the chorion.     

Vessels of the brachial plexus]

The blood supply of brachial plexus is described by means of lightened injected specimens of older human fetus. The following arteries have direct branches to brachial plexus: the aortic arch/brachiocephalica trunk, subclavia a., thyrocervical trunk, ascending cervical a., transverse cervical a., suprascapular a., and the acromial network. Secondary branches leave them that partly anastomose and also return from distal to proximal. The blood supply is luxurious.     

Technical note: the humeral canal approach to the brachial plexus

Many variations to the axillary approach to the brachial plexus have been described. However, the success rate varies depending on the approach used and on the definition of success. Recent work describes a new approach to regional anaesthesia of the upper limb at the humeral/brachial canal using selective stimulation of the major nerves. This report outlines initial experience with this block, describing the technique and results in 50 patients undergoing hand and forearm surgery. All patients were assessed for completeness of motor and sensory block. The overall success rate was 90 percent. Motor block was present in 80 percent of patients. Completion of the block was necessary in 5 patients. Two patients required general anaesthesia. The preponderance of ulnar deficiencies agrees with previously published data on this technique. No complications were described. Initial experience confirms the high success rate described using the Dupré technique. This technically straightforward approach with minimal complications can be recommended for regional anaesthesia of the upper limb.     

Prognosis and early management of birth injuries to the brachial plexus.

Twenty-four cases of birth injury to the brachial plexus were seen in 21 infants over 15 years. Obstetric complications were common, and in 11 cases traction was needed to deliver the shoulders. Three out of every four arms fully recovered after exercises. Splints were not needed. Reconstructive procedures were performed on three permanently paralysed arms when the children were aged about 4. There was no way of predicting which patients would recover. The muscles supplied by the suprascapular nerve were paralysed in all patients, and this paralysis persisted in those whose arms failed to recover fully.     

Angiosomes of the brachial plexus: an anatomical study

This anatomical study analyzed the neurovascular relationships of the brachial plexus. Ten fresh cadaveric brachial plexuses were examined after injection of the arterial system. The vascular anatomical features of the brachial plexus were documented with microdissection after lead oxide/gelatin injection. The specimens were analyzed by using radiography (including digital subtraction techniques) and light-microscopic, macroscopic, and digital photography. Four angiosomes, based on the subclavian, axillary, vertebral, and dorsal scapular arteries, were observed. As noted in previous angiosome studies, connections between angiosome territories lay within tissues, in this case, nerve trunks. Nutrient vessels penetrated nerve trunks at points of branching within the brachial plexus, with a Y-shaped mode of division on entry. The vascular supply was markedly rich, often with true anastomotic connections occurring within the nerves. There was much variation in supply, depending on the vascular anatomical features of the subclavian artery.     

The silkmoth chorion: Morphogenesis of surface structures and its relation to synthesis of specific proteins

The morphogenesis of four spatially differentiated surface regions of the silkmoth eggshell (chorion) has been documented and correlated with differing patterns of chorion protein synthesis within the corresponding secretory cells. During the first half of choriogenesis the polygonal pattern of ridges which cover the entire chorion appears. Regional differences in the morphology of developing ridges are not accompanied by significant protein differences, and thus presumably reflect differences in secretory cell behavior and shape. During the second half of choriogenesis expanding domes of the chorion located immediately beneath three-cell junctions of the overlying secretory surface become prominent surface features exclusively in the aeropyle crown region. Domes are composed of a thin lamellar skin and an inner buttressing “filler.” Continued filler deposition appears to cause a ripping of the lamellar skin, transforming the dome into a multiple-pronged crown that overflows with filler. Continued synthesis of lamellar chorion components elongates and strengthens the crowns until they can stand alone without the support of filler. In the aeropyle crown region, synthesis of regionally specific proteins begins in the second half of choriogenesis and accelerates until the final stages, in parallel with dome/crown formation. The more numerous proteins which are common to all regions are synthesized at approximately equal rates within all regions, and their synthesis decelerates toward the end of choriogenesis. Fifteen of the proteins (excluding filler) which are found predominantly in the aeropyle crown region may be necessary but not sufficient for crown formation, since they also occur in the stripe region (1); presumably the secretory cell surfaces mold the same components differently in the two regions. Filler appears to play an important scaffolding role in crown formation. A group of eight aeropyle crown region-specific chorion proteins which compose filler have been identified on two-dimensional gels and shown to be restricted to one of five previously described classes of chorion proteins.     

Morphogenesis of mechanoreceptor and epidermal cells of crickets during the last instar,and its relation to molting-hormone level

Summary (1) The fine structure of the cercal campaniform sensilla and epidermal cells of Gryllus bimaculatus Deg. (Saltatoria, Gryllidae) was examined, and the ecdysteroid level was monitored throughout the last larval instar. (2) The epidermal cells show changes in shape, cytoplasmic inclusions and differentiation of the apical cell membrane, coupled to the phases of buildup and breakdown of the (cercus) cuticle. (3) The imaginal epicuticle of the epidermal cells begins to form later (by about approximately 6 h) than that of the campaniform sensilla. (4) The campaniform sensilla were studied with respect to (a) the morphogenesis of the cuticular apparatus, (b) the inclusion of phenol oxidases in the cuticular apparatus, and (c) changes in the sensory apparatus preparatory to molting. (5) After apolysis the folding of the tormogen-cell wall into microvilli transiently disappears. Microvilli re-form shortly before imaginai ecdysis, and at the same time an outer receptor-lymph space develops. The role of the tormogen-cell plaques is discussed. (6) The levels of - and -ecdysone were determined separately by radioimmunoassay. (7) At the beginning of the instar the hormone level, especially that of -ecdysone, falls. Prior to apolysis, the concentration of -ecdysone rises, reaching an intermediate peak after apolysis is complete. The maximum hormone concentration (approximately 2,000 ng/g) is reached after the cuticulin layer is deposited, primarily due to the increase in -ecdysone. While the proecdysial cuticle is forming, the hormone titer is reduced; at this time -ecdysone is its chief component. (8) The identification of the ecdysteroids monitored by radioimmunoassay was confirmed by gas chromatography.This paper is dedicated to Professor H. Risler on the occasion of his 65th birthdaySupported by the Deutsche Forschungsgemeinschaft     

Control of plastidic glycolipid synthesis and its relation to chlorophyll formation

Mechanisms restricting the accumulation of chloroplast glycolipids in achlorophyllous etiolated or heat-treated 70S ribosome-deficient rye leaves (Secale cereale L. cv “Halo”) and thereby coupling glycolipid formation to the availability of chlorophyll, were investigated by comparing [¹⁴C]acetate incorporation by leaf segments of different age and subsequent chase experiments. In green leaves [¹⁴C]acetate incorporation into all major glycerolipids increased with age. In etiolated leaves glycerolipid synthesis developed much more slowly. In light-grown, heat-bleached leaves [¹⁴C]acetate incorporation into glycolipids was high at the youngest stage but declined with age. In green leaves [¹⁴C]acetate incorporation into unesterified fatty acids and all major glycerolipids was immediately and strongly diminished after application of an inhibitor of chlorophyll synthesis, 4,6-dioxoheptanoic acid. The turnover of glyco- or phospholipids did not differ markedly in green, etiolated, or heat-bleached leaves. The total capacity of isolated ribosome-deficient plastids for fatty acid synthesis was not much lower than that of isolated chloroplasts. However, the main products synthesized from [¹⁴C]acetate by chloroplasts were unesterified fatty acids, phosphatidic acid, and diacylglycerol, while those produced by ribosome-deficient plastids were unesterified fatty acids, phosphatidic acid, and phosphatidylglycerol. Isolated heat-bleached plastids exhibited a strikingly lower galactosyltransferase activity than chloroplasts, suggesting that this reaction was rate-limiting, and lacked phosphatidate phosphatase activity.