MyoD1 alleles distinguish between the Mm musculus and Mm domesticus subspecies of Mus musculus. SJL/J mice, which belong to the Mm musculus subspecies, are able to regenerate skeletal muscle more efficiently than BALB/c mice which possess the Mm domesticus MyoD1 allele. Hence the possibility that regeneration responses are due to species-specific genetic differences including MyoD1 was investigated in this study. Quantitative morphometric analysis following muscle crush injury of 2 Mm musculus strains, MBK and MGL, has indicated that regeneration phenotype is not species-specific and may not be directly related to MyoD1 alleles. These results contrast with prior investigations conducted in SJL/J and BALB/c mice, and indicate that other genes may have a direct influence on skeletal muscle regeneration.

The reactive formation of lymphoid follicles and germinal centres in lymph nodes, induced by subcutaneous transfer of in vitro activated splenic adherent cells into syngeneic mice, were studied. Adherent cells were obtained by incubating spleen cell suspensions for 24 h and activated by incubating for 1 h in the medium containing keyhole limpet haemocyanin (KLH) absorbed onto alumina. Some of the treated adherent cells were irradiated with 10 Gy x-rays, while others were either not stimulated or were stimulated with alumina-KLH but killed by repeated freezing and thawing. Examination of adherent cell smears immunostained with antibodies against, F4/80, Mac-1, Mac-2 and NLDC-145 indicated that many adherent cells displayed macrophage markers but few displayed the interdigitating cell marker. Animals transfused with KLH-treated adherent cells with or without irradiation showed a marked increase in the number of lymphoid follicles and germinal centres in draining lymph nodes, whereas those transfused with adherent cells which had not been KLH-treated or which had been killed after KLH treatment displayed no significant change in the number of follicles. These results were interpreted as indicating that following transfusion, antigen-activated adherent macrophages migrated into the draining lymph nodes and induced the reactive formation of lymphoid follicles and germinal centres outside preexisting follicles.

Based on a presentation during a Symposium on ‘Phenotypic changes in epithelial development' organised by the Anatomical Society of Great Britain and Ireland held at the Royal Holloway College, Egham, Surrey, in January 2000. The urinary collecting duct system of the permanent kidney develops by growth and branching of an initially unbranched epithelial tubule, the ureteric bud. Formation of the ureteric bud as an outgrowth of the wolffian duct is induced by signalling molecules (such as GDNF) that emanate from the adjacent metanephrogenic mesenchyme. Once it has invaded the mesenchyme, growth and branching of the bud is controlled by a variety of molecules, such as the growth factors GDNF, HGF, TGFβ, activin, BMP-2, BMP-7, and matrix molecules such as heparan sulphate proteoglycans and laminins. These various influences are integrated by signal transduction systems inside ureteric bud cells, with the MAP kinase, protein kinase A and protein kinase C pathways appearing to play major roles. The mechanisms of morphogenetic change that produce branching remain largely obscure, but matrix metalloproteinases are known to be necessary for the process, and there is preliminary evidence for the involvement of the actin/myosin contractile cytoskeleton in creating branch points.

The most frequent disposition of the structures within the ulnar tunnel is for the ulnar nerve to be located medial or posteromedial to the ulnar artery. The structures within the ulnar tunnel are closely related to the medial part of the flexor retinaculum. Lesions of the ulnar nerve and artery during endoscopic decompression of the carpal tunnel have been reported (Agee et al. 1992; Lee et al. 1992; Nath et al. 1993; De Smets & Fabry, 1995). An adequate anatomical knowledge of such structures and their variations is therefore important. During a study of the palmar region, we found that a special branch originated from the ulnar nerve in relation to the flexor retinaculum. Documentation of this variation will contribute to the knowledge of the anatomy of the ulnar nerve and its distal branches.

The Symposium on ‘Mechanisms of Ageing and Longevity’ was held at the Royal Free Campus, Royal Free and University College Medical School, London, on 17 September 1999. It was organised and sponsored by the Anatomical Society of Great Britain and Northern Ireland with generous contributions from BBSRC, AgeNet and Research into Ageing.

The Symposium was organised as a result of recent discoveries in two principal areas: the genetics of longevity regulation in the nematode worm, Caenorhabditis elegans, and the cell biology of ageing in mammalian cells. Papers were presented covering the role of insulin-like signalling, free radical damage and caloric restriction in ageing of invertebrate and mammalian systems. One of the principal aims was to examine the idea that a genetically conserved signalling pathway might regulate ageing processes at both a cellular and an organismal level.

The effect of hypophysectomy on the gastrointestinal tract was studied in the rat 8 wk after operation, particularly regarding the frequency and distribution of serotonin, somatostatin and gastrin-immunoreactive cells. Body weight, the length of the intestine and the thickness of the mucosa of the antrum and small intestine were all reduced in the hypophysectomised rats compared with sham-operated and untreated controls. In the hypophysectomised animals the serotonin-immunoreactive cells were fewer in the antrum and caecum, whereas they were more numerous in the proximal large intestine. There were fewer gastrin-immunoreactive cells in the antrum, while the somatostatin-immunoreactive cells were more numerous in the antrum and caecum. The significant influence of hypophysectomy on the gastrointestinal tract could be direct, but could also be associated with the marked effect of pituitary deficiency on endocrine cells, known to exert both trophic and antitrophic actions. However, it could also be an indirect effect on metabolism, resulting in lower food intake, other endocrine cell systems, and growth factors.

An isolated tracheo-oesophageal fistula could be caused by close proximity of the epithelia of both organs (O'Rahilly & Müller, 1984; Kluth et al. 1987) at certain embryonic stages, the most frequent location being the tracheal bifurcation. Thus the relative position and degree of separation between the digestive and the respiratory tubes throughout their development may be relevant to the origin of this anomaly. The aim of this study was to analyse along the different segments of the tracheo-oesophageal septum (TES) where the closest relationship between both lumina occurred and what degree of separation was present at each segment. Computer imaging techniques were applied on cross sections of a graded series of normal human embryos (Carnegie stages (CS) 13–23). In addition, the differentiation of the primitive TES was also studied (from CS 12) by light microscopy. Between CS 13 and 16 both tubes tended to separate (phase of separation), principally at the proximal segments of the laryngopharyngeal and the tracheo-oesophageal portions of the TES. During this phase the separation between the trachea and oesophagus was wider than between the larynx and pharynx. From CS 17 to CS 23 the digestive and respiratory lumina reached their widest separation at different levels of the laryngopharyngeal portion. Below these levels they tended to come closer together, principally at the proximal segment of the tracheo-oesophageal portion, but also at the distal part of the laryngopharyngeal portion. During this phase of approximation they reached their closest relationship at the proximal (CS 17) and the distal (from CS 18) segments of the tracheo-oesophageal portion. When finally the distal segment of the trachea (which includes the bifurcation) comes closest to the oesophagus, the coats of both organs have already undergone an appreciable differentiation. According to these observations, the origin of the most frequent isolated tracheo-oesophageal fistula at the bifurcation region could not be explained from the normal development of the TES.

We have previously shown that the neurovascular anatomy and length of the long head of biceps femoris (LHBF) is suitable for its possible use in the creation of a dynamic perianal myoplasty to restore faecal continence. If intramuscular arterioarterial anastomoses exist between a muscle's vascular pedicles then the delay procedure, i.e. ligating the vascular pedicles to the transposed section of the muscle, 4–6 wk before transposition, can be used to improve blood flow to the distal part of the transposed muscle. The intramuscular arterial anatomy of 20 biceps femoris muscles was shown by dissection (14) or radiographically (6). The mean entry point of the upper major vascular pedicle to the LHBF was 12 cm (s.d. 3.3) and the mean length of the LHBF was 36.8 cm (s.d. 1.8). Therefore the ratio between upper major vascular pedicle entry point and muscle length in 95% of specimens was 0.33 (0.2). In the present study intramuscular arterioarterial anastomoses were found between the arterial pedicles to the non-transposed and transposed sections of the LHBF and between the long and short heads of this muscle. Using the delay procedure would therefore theoretically allow the intramuscular arterioarterial anastomoses between the arterial pedicle to the nontransposed and transposed sections of the LHBF to open up enhancing blood flow to the distal part of the myoplasty.

A 2-year-old boy presented with a suspected urethrocutaneous fistula. He had been born at 26 wk gestation and spent 14 wk in the special care baby unit with severe respiratory problems and an episode of meningitis. He had not had a urinary catheter in situ or urinary tract infections. Bilateral inguinal hernias had been repaired. At presentation he was below the 3rd centile for height and weight but had reached all other developmental milestones.

In their paper on opossum cartilage, Archer et al. (1996) contend that their ‘data pose questions [ctdot ] to the idea that global patterns of matrix components exist in mammalian articular cartilages’. We believe that this statement is not supported by their data. The points at issue concern the distributions of chondroitin sulphate (CS) and keratan sulphate (KS) in adult cartilage. Earlier work showed that: (1) the highest concentrations of CS are in the midzone of the noncalcified layer of the cartilage (Stockwell & Scott, 1967; Maroudas et al. 1969; Lemperg et al. 1974), while the authors' opossum data apparently show that the intensity of staining with Safranin O (and various antibodies specific for CS) ‘is greatest in the upper third of the tissue depth’; (2) in the noncalcified cartilage, the concentration of KS increases with distance from the articular surface (Stockwell & Scott, 1967; Maroudas et al. 1969; Venn, 1978). By contrast in the opossum, the authors state that there was ‘intense labelling throughout the upper half of the articular cartilage depth’. They considered that this finding, in particular, questions ‘the notions which link KS substitution with conditions of low oxygen tension’, since articular cartilage generally obtains its nutrient and O2 through the articular surface and thence by diffusion through the tissue depth.

Anatomical Society of Great Britain and Ireland

Future meeting

4 September 2000. University of York. One day symposium (part of the International Congress of Histochemistry and Cytochemistry, 3–8 September 2000) on ‘Digital image capture, processing and analysis’.

Mrs Ruby Davies

We announce with regret the death of Mrs Ruby Davies on 18 July 2000. Ruby was Editorial Assistant to the Journal of Anatomy from 1970 to 1991. Ruby was the widow of Professor D. V. Davies, formerly Professor of Anatomy at St Thomas's Hospital Medical School, University of London, and Editor of the Journal. Ruby was a regular attender at meetings of the Anatomical Society of Great Britain and Ireland.

We examined the distribution of parvalbumin in the pigeon thymus by light and electron microscopic immunohistochemistry. Tissues were also examined by conventional electron microscopy to determine the ultrastructure of immunoreactive cells. Parvalbumin immunoreaction was located in epithelial cells of the cortex, which formed dense mesh-like structures. Parvalbumin-positive epithelial cells were classified into 2 types. The first comprised elongated cells. In these, the nucleus was spindle-shaped, oval, or triangular, with a slightly irregular contour and contained rich heterochromatin peripherally. The cytoplasm was pale and processes extended laterally or ramified among the surrounding thymocytes. This type of cell formed the majority of immunoreactive cells. The other cell type consisted of polygonal epithelial cells. The nucleus was oval with deep indentations. Euchromatin occupied a large part of the nucleus. The cytoplasm contained numerous cell organelles compared with the elongated type, in particular, electron-dense vacuoles of various sizes and often bundles of tonofilaments. Both types of epithelial cell were interconnected by desmosomes. No secretory granules were found in the cytoplasm of elongated or polygonal cells. These results indicate the presence of heterogeneous group of parvalbumin-immunoreactive epithelial cells and suggest the likelihood of different functional roles for parvalbumin in the pigeon thymus.

In 1829, von Baer proposed four principles of development, the first of which states that the embryos of a large group of animals have most in common at early stages of development, the specialised features of different subgroups only emerging later. After the publication of Darwin's The Origin of Species in 1859, the relevance of von Baer's principles to evolution was clear to many biologists, who assessed evolutionary relationships on the basis of similarities and differences between early embryos. The validity of these comparisons, carried out more than a century ago, has been confirmed by recent molecular analyses. These new gene-based comparisons have in turn led to a renewed interest in the scientific literature of the first half of the 20th century, which documented in great detail comparative anatomical studies of living and fossil animals.

The past decade has seen a growing synergy between developmental biology and evolutionary studies. As a result, not only is an evolutionary perspective now integral to developmental studies, but palaeontologists have become deeply interested in embryos. This integration was the subject of the symposium of the Winter Meeting of the Anatomical Society, held in London in January 2001, entitled ‘The Evolution of Developmental Mechanisms’. It was a very stimulating and enjoyable meeting that addressed the theme at a number of levels, ranging from the major evolutionary changes resulting from gene duplication to the fine detail of insect wing vein evolution. These two ends of the spectrum of topics reflect Darwin's perspective on von Baer's principles, i.e. his recognition that homologies between different phyla are to be seen in early embryonic and larval structures, while adaptations that enable an organism to survive in its particular environment are the result of changes acting late in development.

The reviews brought together in this volume represent a thoughtful and thought-provoking synthesis of data collected over many years. They show the rewards of detailed and long-term study of embryos that in some cases are difficult to obtain, but represent living clues to the mechanisms underlying important evolutionary transitions. We feel privileged to have had the responsibility for editing this impressive issue of the Journal of Anatomy, which will, we have no doubt, be a significant landmark in the ongoing story of development and evolution, and will be widely cited.

From this issue the Journal of Anatomy will appear on a monthly basis to reduce time from acceptance to publication. The total number of pages per volume will remain the same. As in the past the scope of the Journal will continue to be broad, covering the development, maintenance, evolution and functional significance of structure in man and animals. Preference is given to experimental studies and to contributions on molecular and cell biology rather than purely descriptive studies. All contributions must include clear statements as to the reasons why they have been undertaken and the new information that they contain. There are no page charges and no charge is made for colour illustrations if the editors consider that they are essential.

The bagpipe-related homeobox-containing genes are members of the NK family. bagpipe (bap) was first identified in Drosophila and there are three different bagpipe-related genes in vertebrates. Only two of these are found in mammals, the Nkx3.1 and the Bapx1 (Nkx3.2) gene. The targeted mutation in the mouse Bapx1 gene shows a vertebral phenotype in which the ventromedial elements are lacking; these are the centra and the intervertebral discs. In addition, a region of gastric mesenchyme is abnormal. This mesenchyme surrounds the posterior region of the presumptive stomach and duodenum, and in the mutant fails to support normal development of the spleen. In Drosophila, bagpipe has a role in gut mesoderm and the mutant embryos have no midgut musculature. Thus bap related genes in mouse and Drosophila have roles in patterning gut mesoderm; however, neither of the mammalian genes has a discernible role in the gut musculature. In contrast, both mammalian genes have roles in developmental processes that have appeared recently in evolution. The Bapx1 gene found in fish, amphibians, birds and mammals appears to have derived vertebrate specific functions sometime after the split between the jawless fish and gnathostomes.