Caudal Folds Research Articles

A new species of Aleurolobus Quaintance & Baker, 1914 (Hemiptera, Aleyrodidae) from China infesting Murrayaexotica L.

A new whitefly species, Aleurolobusrutaesp. nov., collected on Murrayaexotica (Sapindales, Rutaceae) leaves in the Maolan National Nature Reserve, Guizhou, China, is described and illustrated. Some of the individuals were infected with Aschersoniaplacenta, an entomopathogenic fungus. The insect is circular in shape and characterized by a very wide submarginal region, and the submarginal furrow is almost continuous, with only a small break at the caudal furrow. Anterior and posterior marginal setae are absent, but setae are present on the 8th abdominal segment. Thoracic and caudal tracheal folds are discernible.

TMEM132A ensures mouse caudal neural tube closure and regulates integrin-based mesodermal migration.

Coordinated migration of the mesoderm is essential for accurate organization of the body plan during embryogenesis. However, little is known about how mesoderm migration influences posterior neural tube closure in mammals. Here, we show that spinal neural tube closure and lateral migration of the caudal paraxial mesoderm depend on transmembrane protein 132A (TMEM132A), a single-pass type I transmembrane protein, the function of which is not fully understood. Our study in Tmem132a-null mice and cell models demonstrates that TMEM132A regulates several integrins and downstream integrin pathway activation as well as cell migration behaviors. Our data also implicates mesoderm migration in elevation of the caudal neural folds and successful closure of the caudal neural tube. These results suggest a requirement for paraxial mesodermal cell migration during spinal neural tube closure, disruption of which may lead to spina bifida.

Morphologic alterations of the genital mesentery implicated in testis non-descent in rats prenatally exposed to flutamide.

There is an endless debate on whether androgens mediate testis descent through developmental changes in the gubernacular or the cranial suspensory ligament. To investigate the relation of any possible morphologic changes in the genital mesentery, that is, the system of genital peritoneal folds including the gubernacular and cranial suspensory ligaments, with the event of testis non-descent in rats prenatally exposed to the antiandrogen flutamide. Time-pregnant Sprague Dawley rats received flutamide (100mg/kg/d) or vehicle subcutaneously on gestational days 16-17. Flutamide-treated male offspring (n=67), and vehicle-treated male (n=34) and female (n=28) offspring were surgically explored under microscope on postnatal day 50. Testicular position was examined bilaterally. Dimensions of genital mesentery parts were also assessed bilaterally. Association of flutamide-induced morphologic changes with descended (n=61) and undescended (n=50; 33 cryptorchid and 17 ectopic) testes was investigated with logistic regression analysis. The male genital mesentery comprised a cranial and a caudal fold converging on the vas deferens. Flutamide resulted in enlarged cranial and reduced caudal folds. Of all flutamide-induced alterations, the increased length of the posterior fixation of the cranial fold and the decreased length of the gubernacular ligament of the caudal fold were found to independently increase the odds of testis non-descent. Testicular ectopy, unlike cryptorchidism, was associated with a short gubernacular ligament only. The female genital mesentery consisted of a cranial fold only. Our findings showed a combined contribution of both cranial and caudal folds of the genital mesentery to testis non-descent, through an abnormally long mesentery root and an abnormally short gubernacular ligament, respectively. Inhibition of male-specific development of the genital mesentery with flutamide did not result in a feminized architecture.

Shp2-Mitogen-Activated Protein Kinase Signaling Drives Proliferation during Zebrafish Embryo Caudal Fin Fold Regeneration.

ABSTRACTRegeneration of the zebrafish caudal fin following amputation occurs through wound healing, followed by formation of a blastema, which produces cells to replace the lost tissue in the final phase of regenerative outgrowth. We show that ptpn11a−/− ptpn11b−/− zebrafish embryos, lacking functional Shp2, fail to regenerate their caudal fin folds. Rescue experiments indicated that Shp2a has a functional signaling role, requiring its catalytic activity and SH2 domains but not the two C-terminal tyrosine phosphorylation sites. Surprisingly, expression of Shp2a variants with increased and reduced catalytic activity, respectively, rescued caudal fin fold regeneration to similar extents. Expression of mmp9 and junbb, indicative of formation of the wound epidermis and distal blastema, respectively, suggested that these processes occurred in ptpn11a−/− ptpn11b−/− zebrafish embryos. However, cell proliferation and MAPK phosphorylation were reduced. Pharmacological inhibition of MEK1 in wild-type zebrafish embryos phenocopied loss of Shp2. Our results suggest an essential role for Shp2a–mitogen-activated protein kinase (MAPK) signaling in promoting cell proliferation during zebrafish embryo caudal fin fold regeneration.

Vangl2 disruption alters the biomechanics of late spinal neurulation leading to spina bifida in mouse embryos.

ABSTRACTHuman mutations in the planar cell polarity component VANGL2 are associated with the neural tube defect spina bifida. Homozygous Vangl2 mutation in mice prevents initiation of neural tube closure, precluding analysis of its subsequent roles in neurulation. Spinal neurulation involves rostral-to-caudal ‘zippering’ until completion of closure is imminent, when a caudal-to-rostral closure point, ‘Closure 5’, arises at the caudal-most extremity of the posterior neuropore (PNP). Here, we used Grhl3Cre to delete Vangl2 in the surface ectoderm (SE) throughout neurulation and in an increasing proportion of PNP neuroepithelial cells at late neurulation stages. This deletion impaired PNP closure after the ∼25-somite stage and resulted in caudal spina bifida in 67% of Grhl3Cre/+Vangl2Fl/Fl embryos. In the dorsal SE, Vangl2 deletion diminished rostrocaudal cell body orientation, but not directional polarisation of cell divisions. In the PNP, Vangl2 disruption diminished mediolateral polarisation of apical neuroepithelial F-actin profiles and resulted in eversion of the caudal PNP. This eversion prevented elevation of the caudal PNP neural folds, which in control embryos is associated with formation of Closure 5 around the 25-somite stage. Closure 5 formation in control embryos is associated with a reduction in mechanical stress withstood at the main zippering point, as inferred from the magnitude of neural fold separation following zippering point laser ablation. This stress accommodation did not happen in Vangl2-disrupted embryos. Thus, disruption of Vangl2-dependent planar-polarised processes in the PNP neuroepithelium and SE preclude zippering point biomechanical accommodation associated with Closure 5 formation at the completion of PNP closure.

A new species of Aleuromarginatus Corbett, 1935 with a key and checklist of Chinese species (Hemiptera, Aleyrodidae).

A new whitefly species, Aleuromarginatus dielsianae Wang & Xu, sp. n. collected from Millettia dielsiana Harms (Rosales: Fabaceae) in Jiangshan (28°40'N, 118°40'E, 512 m) and Xinchang (29°22'N, 120°46'E, 308 m), Zhejiang, China, is described and illustrated. This new species is characterized by the dark brown lateral margin area and a pair of longitudinal furrows extending from the cephalothorax to the vasiform orifice. The submargin has an elongate-oval fold at the base of each marginal tooth and with 3-4 rows of irregular shaped papillae, nine pairs submedian setae and 13 pairs submarginal setae. Thoracic and caudal tracheal folds and pores discernible. An identification key and checklist of species of Aleuromarginatus known from China are provided.

The histological components of the phoniatrical body-cover model in minipigs of different ages.

Pigs are models in human phoniatry. However, features of maturation and ageing have not been considered with regard to the so-called body-cover model in this species. Therefore, the glottis of “young” (2–3 months; n = 6) and “old” (4–7 years; n = 6) minipigs was investigated. Their cranial (CraF) and caudal (CauF) vocal folds were histomorphometrically and stratigraphically analysed with emphasis on their amounts of collagen structures and elastic fibres. A dense subepithelial layer (SEL) was a distinct feature of CraF and CauF of both age groups; it was spread upon the underlying loose, flexible “cover” like a fibro-elastic membrane. The “cover” was characterised by the so-called superficial layer (SL), which was distinctly loose in the “young” minipigs, but had a much denser texture in the “old” minipigs. Here, the SL was dominated by elastic fibres in the CraF, but was of mixed qualities (collagenous and elastic) in the CauF. The structural requirements for the SL’s function as a loose “cover” were thus met only in the “young” animals. A clearly demarcated intermediate layer (IL)—characterised by high amounts of elastic fibres (as in humans)—was only found in the CraF of the “young” animals. In the “old” animals, it had lost its demarcation. In the depth of the CraF of the “old” animals, many thick collagen fibre bundles were detected in a location equivalent to that of the vocal muscle in the CauF. The development of their large diameters was interpreted as part of the maturation process, thereby supporting the hypothesis of their functional importance as a component of the “body.” In the CauF, the amounts of collagen structures increased throughout the entire lamina propria, resulting in a loss of demarcated stratigraphical subdivisions in the “old” minipigs. This situation resembled that described in the vocal fold of geriatric humans.

The stratigraphical organisation of the microvascular systems of the porcine vocal folds.

The cranial and caudal vocal folds (CraF, CauF) of the glottis of adult minipigs (11-27 months; n = 12) were examined after immunohistochemical application of polyclonal anti-von-Willebrand-Factor and anti-Smooth-Muscle-Actin in serial paraffin sections. This examination aimed at a stratigraphical analysis of microvessels; data were compared with findings in humans which had been reported in the literature. (1) The distribution of the microvessels was very heterogeneous in the CraF and in the CauF, but a common pattern existed in both. (2) Characteristic vascular zones and rows were detected; each of them displayed a specific distribution and density of blood capillaries, arterioles, venules, lymphatic capillaries, and lymphatic precollectors. (3) A striking feature was the presence of a subepithelial Avascular Band and of a focal Avascular Area within the lamina propria of the fold's crests. (4) The vascular zones, the rows, the Avascular Band, and the Avascular Area could be allocated to specific layers of the lamina propria: subepithelial, superficial, intermediate, deep layer. (5) The loose Avascular Area at the level of the superficial layer of the lamina propria (in both CraF and CauF) corresponded to Reinke's space in humans in terms of structure and location. (6) The direction/course of blood and lymphatic microvessels shared common features with that of the human vocal fold.

Histomorphometric analysis of collagen and elastic fibres in the cranial and caudal fold of the porcine glottis.

The porcine glottis differs from the human glottis in its cranial and caudal vocal folds (CraF, CauF). The fibre apparatus of these folds was studied histomorphometrically in adult minipigs. For object definition and quantification, the colour-selection tools of the Adobe-Photoshop program were used. Another key feature was the subdivision of the cross-sections of the folds into proportional subunits. This allowed a statistical analysis irrespective of differences in thickness of the folds. Both folds had a distinct, dense subepithelial layer equivalent to the basement membrane zone in humans. The subsequent, loose layer was interpreted - in principle - as being equivalent to Reinke's space of the human vocal fold. The next two layers were not clearly separated. Due to this, the concept of a true vocal ligament did not appear applicable to neither CauF nor CraF. Instead, the body-cover model was emphasized by our findings. The missing vocalis muscle in the CraF is substituted by large collagen fibre bundles in a proportional depth corresponding to the position of the muscle of the CauF. The distribution of elastic fibres made the CraF rather than the CauF more similar to the human vocal fold. We suggest that these data are useful for those wishing to use the porcine glottis as a model for studying oscillatory properties during phonation.

Synovial folds in equine articular process joints

Cervical synovial folds have been suggested as a potential cause of neck pain in humans. Little is known about the extent and characteristics of cervical synovial folds in horses. The objective of this explorative study was to determine the frequency of synovial folds in equine cervical articular process joints and to provide a characterisation of the size and morphology of the synovial folds. Equine cervical articular process joints from 6 horses were included in the study, ranging from cervical vertebra 2 (C2) to cervical vertebra 7 (C7) bilaterally. The articular process joints were dissected, and the cranial and caudal synovial folds of each joint were measured and embedded in paraffin. Synovial folds were analysed histologically and classified according to type, as adipose, fibrous and mixed type. Factors potentially influencing fold size were investigated, including joint number (from C2/C3 to C6/C7), fold type, position of fold within the joint (cranial or caudal) and side of neck (right or left). Synovial folds were identified in 98% of cervical articular process joints examined. The width of the synovial folds varied from 4 to 41 mm, and the height from 1 to 17.8 mm. Thirty-eight per cent of the synovial folds were of adipose type, 41% of fibrous type and 21% of mixed type. Synovial fold size was significantly influenced by the side of the neck and fold type. This study provides a characterisation of the frequency, size and morphology of equine cervical synovial folds in 6 horses. Synovial folds were present in 98% of the cervical articular process joints examined, and the size of the synovial folds indicates that they could be damaged by acute injury or chronic disease in the cervical articular process joints.

Length of docked tail and the incidence of rectal prolapse in lambs.

A multistate cooperative study was conducted to study the current issue of tail length in docked lambs and its relationship to incidence of rectal prolapse. A total of 1,227 lambs at six locations were randomly allocated to two or three tail dock treatments: 1) short--tail was removed as close to the body as possible, 2) medium--tail was removed at a location midway between the attachment of the tail to the body and the attachment of the caudal folds to the tail, and 3) long--tail was removed at the attachment of the caudal folds to the tail. Short-docked lambs had a greater (P < 0.05) incidence of rectal prolapse (7.8%) than lambs with a medium (4.0%) or a long (1.8%) dock. Female lambs had a higher (P < 0.05) incidence of rectal prolapse than male lambs. At two stations, lambs were finished either in a feedlot on a high-concentrate diet or on pasture with no grain supplementation. At one station, with a very low incidence of rectal prolapse, there was no difference in incidence between lambs finished in the feedlot or on pasture; however, at the station with a relatively high incidence of rectal prolapse, lambs in the feedlot had a higher (P < 0.05) incidence than lambs on pasture. The half-sib estimate of heritability for the incidence of rectal prolapse was low (0.14). The results of this study strongly implicate short dock length as a cause of rectal prolapse in lambs finished on high-concentrate diets. Furthermore, the results of this study and the only other study known conducted on this issue strongly suggest that docking lambs at the site of the attachment of the caudal folds to the tail will result in a negligible incidence of rectal prolapse.

Two divergent slit1 genes in zebrafish.

Members of the Slit family regulate axon guidance and cell migration. To date, three vertebrate slit1 genes have been identified in mammals and orthologs of two, slit2 and slit3, have been identified in zebrafish. Here, we describe the cloning of full-length cDNAs for two zebrafish slit orthologs, slit1a and slit1b. Both predicted proteins contain the conserved motifs that characterize other vertebrate Slits. slit1a and slit1b are both expressed in the midline, hypochord, telencephalon, and hindbrain. Apart from these shared expression domains, however, their expression patterns largely differ. Whereas slit1a is expressed broadly in the central nervous system (CNS) and in the somites, pectoral fin buds, tail bud, and caudal fin folds, slit1b is expressed in the olfactory system throughout embryonic and larval development, and in the retina during larval stages. Their expression patterns, particularly that of slit1a, suggest that Slit proteins may have roles in tissue morphogenesis in addition to their established roles in axon guidance and cell migration.

P63 Coordinates Anogenital Modeling and Epithelial Cell Differentiation in the Developing Female Urogenital Tract

p63 is a p53 homologue required for cutaneous development that is expressed in immature squamous epithelium and reserve cells of the cervix. Humans with p63 mutations exhibit defects in limb, accessory organ (skin appendage, breast, prostate), and genitourinary development. Because p63 expression patterns imply a strong role of the gene in the female genital tract development, newborn female p63-/-, +/-, and +/+ mice were examined in situ, dissected, and compared. Nuclear p63 protein was localized to the skin, vagina, bladder, urethra, and basal columnar cells of the caudal uterus in p63+/+ and +/- animals. p63-/- mice exhibited abnormal genital morphogenesis with hypoplastic genitalia, a single cloacal opening, and persistence of columnar epithelium at lower genital tract sites that normally undergo squamous and urothelial differentiation. The defects observed support p63-dependent pathways of genital tract development that permit externally, ectodermal basal cell replenishment integral to reciprocal epithelial stromal signaling, urorectal septation, and modeling of the external genitalia; and internally, the emergence of basal epithelial cell populations capable of divergent epithelial cell differentiation in the vagina, cervix, and urinary tract. Defects in the first pathway explain imperforate anus, vaginal septum, genital hypoplasia, and micropenis reported in humans with p63 mutations. The second is necessary for the generation of multipotential reserve cells in the cervix and may be operative in other epithelial stromal interactions integral to the emergence of uterine basal cells later in life.

Genetic analysis of fin formation in the zebrafish, Danio rerio.

In the zebrafish, Danio rerio, a caudal and pectoral fin fold develop during embryogenesis. At larval stages the caudal fin fold is replaced by four different fins, the unpaired anal, dorsal and tail fins. In addition the paired pelvic fins are formed. We have identified a total of 118 mutations affecting larval fin formation. Mutations in 11 genes lead to abnormal morphology or degeneration of both caudal and pectoral fin folds. Most mutants survive to adulthood and form a surprisingly normal complement of adult fins. Mutations in nine genes result in an increased or reduced size of the pectoral fins. Interestingly, in mutants of one of these genes, dackel (dak), pectoral fin buds form initially, but later the fin epithelium fails to expand. Expression of sonic hedgehog mRNA in the posterior mesenchyme of the pectoral fin bud is initiated in dak embryos, but not maintained. Mutations in five other genes affect adult fin but not larval fin development. Two mutants, longfin (lof) and another longfin (alf) have generally longer fins. Stein und bein (sub) has reduced dorsal and pelvic fins, whereas finless (fls) and wanda (wan) mutants affect all adult fins. Finally, mutations in four genes causing defects in embryonic skin formation will be briefly reported.

Amniogenesis in Schreiber’s long-fingered batMiniopterus Schreibersii Natalensis

an amnion by folding as described for the tree-tailed bat Tadarida hrasiliensis cynocephala (Stephens 1962). Schreiber's long-fingered bat, Miniopterus schreibersii natalensis, is seasonally monoestrous producing a single off­ spring in November. It has a bicornuate uterus with asymmet­ rically sized horns. The right horn is twice the length of the left one. All implantations occur in the right uterine horn, with 90% of the conceptuses originating from the left ovary (Van der Merwe 1986). Implantation is superficial and the blastocyst expands within the uterine horn. Orientation of the point of initial trophoblastic attachment, like the orientation of the embryonic disc, is anti-mesometrial (Van der Merwe 1982). Soon after the endodermic cells have started to delam­ inate from the inner cell mass during the pre-implantation period, a single cavity, the primitive amniotic cavity, devel­ ops between the remainder of the inner cell mass by means of cavitation (Van der Merwe 1980). However, this cavity as well as its roof (composed of cells of the embryonic mass and overlying trophoblast) do not participate in the formation of the definitive amniotic cavity or definitive amnion respec­ tively. At the stage when the trophoblast covering the embry­ onic pole of the blastocyst starts to proliferate to form the invading syncytiotrophohlast, the floor of the primitive amni­ otic cavity flattens off (Van der Merwe 1982). Owing to this action, the roof of the primitive amniotic cavity, as well as the overlying cytotrophoblast, becomes stretched and progres­ sively thinner until it eventually ruptures and disappears. The embryonic disc at this stage is roofed only by the syncytiotro­ phoblast (Van der Merwe 1982). The purpose of the present study was to determine how the pleuramnion in the superficially implanting Schreibers' long-fingered bat is formed. The main aim was to determine whether the cephaliclhead, lateral and caudal folds develop simultaneously and contribute equally to its formation. There has been some controversy as far as this aspect is concerned because, although authors refer to these folds, some do not elaborate on the contribution made by each of these folds dur­ ing amniogenesis. They normally only mention that the free edges of the folds meet dorsally of the embryo. In the pig these circumferential amniotic folds are in reality all directly continuous with each other (Patten 1948). This, indeed, is expected to be the case in the majority of mammals where a pleuramnion exists. In Schreibers' long-fingered bat these folds eventually become continuous, but this occurs only at a later stage of amniogenesis (see below). Twenty Schreiber's long-fingered bats carrying embryos were collected during July and August at Sandspruit Cave No.1 (24'37'S, 27°40'E) in the northern Transvaal bushveld. Following paraffin-wax embedding, all the genital tracts were serially sectioned at 5 11m and the mounted sections stained:with Ehrlich's haematoxylin and counter-stained with eosin. The sections revealed that upgrowing folds from the peri­ meter of the embryonic disc in Schreiber's long-fingered bat, brought with them ectoderm and extra-embryonic mesoderm (Figures la, b). Because this is a double fold of soma top leur a, the outer part comes into close contact with the syncytiotro­ phoblast. As growth of the folds progresses, the outer layer of the folds eventually covers more of the syncytiotrophoblast overlying the embryonic pole. Finally the folds unite dorsally,

FORSE-1: a positionally regulated epitope in the developing rat central nervous system

We designed a protocol to identify cell surface molecules expressed in restricted spatial patterns in the developing central nervous system (CNS) that might be regulated by regionally restricted transcription factors. The immunogen was a membrane fraction from NT2/D1 embryocarcinoma cells that were induced to differentiate into neurons and upregulate Hox gene expression in response to retinoic acid. One monoclonal antibody (mAb), FORSE-1, specifically labels the rostral rat CNS from the earliest stages. Staining is observed in the rostral but not caudal neural folds of the embryo prior to neural tube closure. Staining is enriched in the forebrain as compared to the rest of the CNS, until E18. Between E11.5 and E13.5, only certain areas of the telencephalon and diencephalon are labeled. Later, up to E17.5, FORSE-1 labeling is specifically restricted to the telencephalon, where a correlation with mitotic activity is apparent: the ventricular zone labels with FORSE-1, while the cortical plate is negative. The staining of the neuroepithelium is intensified by acetone fixation, which also reveals, between E11.5 and E13.5, a dorsoventrally restricted, FORSE-1-positive region of the spinal cord. After E18, the entire CNS is labeled, through adulthood. The mAb labels the surfaces of dissociated, living cells. Other, non-CNS areas of FORSE-1 labeling are nasal and otic placodes, nasal epithelium, nasal glands, and early (E9.5-10.5) endoderm. mAb FORSE-1 recognizes an epitope present on both a high-molecular-weight (> 200 kDa) proteoglycan from embryonic and early postnatal brain, and on a 80 kDa doublet that is restricted to the CNS in the adult. These findings suggest the FORSE-1 antigen as a candidate cell surface molecule for mediating regional specification from the earliest stages of CNS development.

The development of the caudal ligaments of the mesonephros and of the gonads: a contribution to the development of the human gubernaculum (Hunteri).

The formation of the two caudal mesonephric folds is described. The plica uropelvina becomes the plica urogenitalis as soon as the paramesonephric (Müllerian) duct grows, and the plica inguinalis runs over the ridge of the umbilical artery to the ventral abdominal wall. Within the plica inguinalis the inguinal or caudal mesonephric ligament is formed directly subjacent to the coelomic epithelium. It interacts intensively with the mesenchyme sheath of the paramesonephric (Müllerian) duct in stage 21. It is separated by loose mesenchyme from the subjacent mesonephros and mesonephric (Wolffian) duct which therefore it does not pass beneath. In stage 23, and during the early fetal period, the caudal gonadal ligament is formed. It arises from the caudal pole of the gonads and proliferates in the space between the two genital ducts. Only the duct not destined to disappear associates with it. Therefore, in males the gubernaculum consists of the inguinal ligament of the mesonephros only. Its significance for the descent of the testis is discussed. In females the inguinal and the caudal gonadal ligaments fuse into a single strand and together form the gubernaculum.

Aberrant convergence of the neural folds in the mouse mutantvl

Progressive changes in the dorsolateral angles (DA) and ventral angle (VA) during elevation and convergence of the caudal neural folds were morphometrically analyzed in normal and dysraphic abnormal embryos of the mouse mutant vacuolated lens (vl), and correlations with the configuration of microfilaments in the apices of neuroepithelial cells were made by means of ultrastructural cytochemistry. In 22-28 somite stage abnormal (vl/vl) embryos, the DA and VA are larger than those in their normal counterparts at each comparable level of the caudal neural folds, suggesting that defective convergence involves both the DA and VA in this mutant. In 30-35 somite stage abnormal embryos, the VA is likewise larger than that in normal embryos in which the neural folds have converged and closed; however, the DAs are much smaller, indicating that a medial collapse of the dorsal ends of the neural folds may occur secondary to the closure failure. At the DA, the ultrastructural configuration of microfilaments is similar in abnormal and normal embryos in terms of their circumferential arrangement around the perimeters of the neuroepithelial cell apices. In abnormal embryos, however, the bundles of microfilaments are more delicate and less prominent than in normal embryos; thus it is possible that a quantitative and/or functional deficiency in these elements may be involved in the failure of the abnormal neuroepithelium to bend properly during convergence of the neural folds.

Early sonographic diagnosis of body stalk anomaly

Ultrasonographic features of a fetus at 18 weeks of gestation suggesting a body stalk anomaly are presented. These included a large abdominal anterior wall defect in apparent continuity with the placenta, severe kyphoscoliosis of the lower spine, the absence of one kidney, and a very short umbilical cord with only one umbilical artery. The amniotic fluid was reduced and the fetus was almost immobile at short-interval ultrasound examinations. The pregnancy was terminated and autopsy of the fetus showed abnormalities compatible with maldevelopment of both cephalic and caudal embryonic folds.

Immunofluorescent analysis of fibronectin and laminin distribution in the vl mutant mouse.

The distribution of fibronectin and laminin was determined in the basement membrane surrounding the caudal neural tube and at the site of initial apposition of the caudal neural folds by means of indirect immunofluorescence histochemistry on 9.0- to 10.5-day mouse embryos fixed in Carnoy's solution and serially sectioned in paraffin. At early phases of development of normal (+/+) and abnormal (vl/vl) embryos the dorsolateral neural basement membrane overlying putative neural crest cells caudal to the hindlimb shows a patchy fibronectin reaction, with laminin virtually absent. In older embryos, both components are present but are discontinuous overlying the neural crest. The results suggest that since discontinuities occur in the basement membrane of abnormal as well as normal embryos, the neutral crest cells are not prevented from emigrating from the abnormal neural tube; thus the faulty neural fold fusion that characterizes vl/vl embryos does not appear to be due to a suppression of emigration by the basement membrane. The results also demonstrate the advantages and reliability of embedding in paraffin for analysis of serially sectioned pathological material by means of indirect immunofluorescence, provided that normal controls and abnormals are processed simultaneously.