Beverley Kramer

The origin of gut and pancreatic neuroendocrine (APUD) cells—the last word?

The evidence that gut and pancreatic endocrine cells are not derivatives of the neural crest is overwhelming: yet this conclusion is still not universally accepted. In this editorial attention is drawn to the body of experimental evidence which points conclusively to gut and pancreatic endocrine cells arising from endoderm, not the neural crest, the neurectoderm or neuroendocrine programmed epiblast. Copyright

Anatomy: spotlight on Africa.

Anatomy departments across Africa were surveyed regarding the type of curriculum and method of delivery of their medical courses. While the response rate was low, African anatomy departments appear to be in line with the rest of the world in that many have introduced problem based learning, have hours that are within the range of western medical schools and appear to be well resourced. Human body dissection is a constant and strong aspect of the majority of the courses surveyed. The staff to student ratio appears to be relatively high in Africa, but in many of the responding African institutions, there appears to be little difficulty in attracting suitable faculty (including those who are medically qualified) to teach anatomy. Retaining this faculty, in some cases, may be difficult because of a global demand for anatomy educators. Anat Sci Ed 1:111–118, 2008.

Immunolocalization of fibroblast growth factor-2 (FGF-2) in the developing root and supporting structures of the murine tooth

SummaryEpithelio–mesenchymal interactions are active during the development of the root of the tooth and are regulated by a variety of growth factors, such as fibroblast growth factors. FGF-2, 3, 4, and 8 have all been shown to play a role in the development of the crown of the tooth, but less is known about the factors that govern root formation, particularly FGF-2. The aim of this study was thus to elucidate the spatial and temporal expression of FGF-2 in the root of the developing tooth, as this growth factor is believed to be a mediator of epithelio–mesenchymal interactions. Parasagittal sections of the maxillary and mandibular arches of post-natal mice were utilized and the roots of the molar teeth were studied. Immunocytochemistry utilizing an antibody to FGF-2 was performed on sections of teeth at various stages of development. Intense immunostaining for FGF-2 was observed in differentiating odontoblasts at the apical end of the tooth and in the furcation zone of the developing root at all the stages examined. FGF-2 localization was also observed in cementoblasts on post-natal days 16, 20 and 24. The pattern of localization of FGF-2 in the developing root suggests that this growth factor may participate in the signaling network associated with root development.

The embryonic origin of endocrine cells of the gastrointestinal tract

Abstract Combinations of quail endoderm with chick mesoderm and vice versa were cultured in in vitro and then as chorioallantoic grafts. The areas of the germ layers used were delimited in head fold to 8-somite embryos so as to exclude neural crest cells. Various categories of gut endocrine-like cells were distinguished from each other in the grafts by immunocytochemistry and electron microscopy. In the categories consisting of adequate numbers of cells, when quail endoderm was combined with chick mesoderm, the gut endocrine cells contained the exceptionally large nucleoli characteristic of quail cells. When quail mesoderm and chick endoderm were combined, the endocrine cells contained chick nuclei. It is concluded that at least the majority of gut endocrine cell types at present known are derived from the endoderm and not from the neural crest, other ectoderm, or mesoderm.

Hyperstimulation affects vascular permeability at implantation sites in the rat endometrium

PurposeIt has previously been shown that deleterious changes occur in the epithelium and stroma of the endometrium of the rat following ovarian hyperstimulation by exogenous gonadotropins. The purpose of the present study was to investigate the formation of possible implantation sites following hyperstimulation. Female rats (n =8) were injected in phase with their estrous cycle with follicle stimulating hormone (FSH), followed by human chorionic gonadotropin (hCG), and mated at proestrous. Control rats (n =6) were uninjected and mated at proestrous. Animals were killed at 5.5 days of pregnancy. The pontamine blue technique was used to demonstrate the permeability of the uterine vessels. Implantation sites were demonstrated in the uterine horns of all control animals by segmental blue banding.ResultsBlue staining occurred only in a portion of one horn of one hyperstimulated animal. While fenestrations were found in the walls of capillaries of control animals, similar fenestrations were not observed in the vessels of hyperstimulated animals.ConclusionAs the walls of vessels in the hyperstimulated animals failed to become permeable, and as no implanting embryos were found in these animals, it is concluded that there was an inability of the endometrium to form implantation sites. These changes may impede attachment and implantation of the embryo.

A biochemical comparison of the in vivo effects of Bulbine frutescens and Bulbine natalensis on cutaneous wound healing.

AIM OF THE STUDY In South Africa the local population relies extensively on indigenous plants in the formulation of traditional medicines to treat skin ailments. The scientific merits of many of these plants used to treat wounds and burns are yet to be validated. Bulbine natalensis and Bulbine frutescens of the Asphodelaceae family are indigenous to only southern Africa and are widely used as a skin remedy. This study aimed to explore the scientific value of these plants through investigating the in vivo biochemical effects of Bulbine natalensis and Bulbine frutescens on cutaneous wounds. MATERIAL AND METHODS Excisional and incisional wounds treated with either B. natalensis or B. frutescens and mirrored control wounds were created on the back of 12 domestic pigs. Wound contraction was recorded daily. The excisional wounds, biopsied at days 2, 4, 7, 10 and 16, were used to analyse the biochemical composition of the wounds by estimating the total amount of protein, DNA, collagen and hexosamine present. The incisional wounds, biopsied at day 16, were used to test the tensile strength of the healed wounds using a tensiometer. RESULTS Wound contraction following treatment with Bulbine natalensis on days 2, 4 and 10 (p=.004, 0.007 and 0.03, respectively), and Bulbine frutescens on day 4 (p=0.004) increased significantly when compared to the corresponding untreated wounds. The tensile strength of the wounds treated with the leaf gels was significantly stronger than that of the untreated wounds. There was also a significant increase in the collagen, protein and DNA content of the Bulbine natalensis- and Bulbine frutescens-treated wounds compared with that of the untreated wounds (collagen content: p=0.014 and 0.018; protein content: p=0.03 and 0.04; DNA content p=0.04 and 0.04; respectively) over the 16-day experimental period. Treatment with both leaf gels followed the same pattern in hexosamine content with a maximum hexosamine content on day 4 followed by a steady decrease to day 16. No significant difference between the hexosamine content of the wounds of animals treated with either Bulbine frutescens or Bulbine natalensis was found. CONCLUSIONS These findings validate the traditional use of the leaf gel extracts of B. frutescens and B. natalensis in the treatment of wounds and may warrant further investigation towards producing a low-cost effective topical treatment for wounds.

A quantitative assessment of the jugular foramen

While it is generally accepted that the right jugular foramen is larger than the left, little quantitative evidence exists on the exocranial and endocranial openings of this foramen. The present study set out to clarify and quantify measurements of the two openings. The dimensions of the exocranial and endocranial openings of the jugular foramen and the volume and height of the jugular fossa were examined in a total sample of 93 skulls from white and black, male and female South Africans. The volume of the jugular fossa was determined with the use of a dental impression material. The exocranial area of the right jugular foramen was significantly larger (p < 0.05) than the left in the black group, while the endocranial area of the right foramen was significantly larger (p < 0.05) than the left only in black males. The height of the jugular fossa was significantly larger (p < 0.05) on the right side only in the black group. The volume of the jugular foramen was significantly larger (p < 0.05) on the right side only in females of both groups. Although the jugular foramen is generally larger on the right side than on the left, its size as well as the volume and height of the jugular fossa is variable in different groups and sexes.

EXOGENOUS GONADOTROPIN ADMINISTRATION AFFECTS THE GLYCOCALYX OF RAT ENDOMETRIAL EPITHELIAL CELLS DURING THE PERIOD OF IMPLANTATION

PurposeExogenous gonadotropins which cause superovulation are known to effect endometrial morphology, including the glycocalyx of surface epithelial cells. Certain of the carbohydrates in the glycocalyx of surface epithelial cells may be involved in the attachment and implantation of the blastocyst.MethodsThe effect of exogenous gonadotropins on specific carbohydrates in the glycocalyx of the rat endometrium around the time of implantation was investigated. Lectin-avidin-biotin-ferritin cytochemistry was used to ascertain which carbohydrates were affected. The lectins soybean agglutinin, fucose binding protein and wheat germ agglutinin were used.ResultsStatistically significantly less lectin was associated with the apical membrane of surface epithelial cells of animals following hyper stimulation than in noninjected pregnant animals.ConclusionsThe reduction in the carbohydrates contributes to a reduced receptivity of the endometrium for the blastocyst.

The effect of retinoic acid on the proportion of insulin cells in the developing chick pancreas.

SummaryWe assessed the potential role of all-trans-retinoic acid on the developing chick pancreas, specifically with regard to the proportions of insulin cells. The endodermal component of the dorsal pancreatic bud of 5-d-old chick embryos was cultured on Matrigel. Retinoic acid (10−6 or 10−5M) was added to a standard serum-free medium, Hams F12 containing insulin, transferrin and selenium (F12.ITS). Control grafts were cultured in F12.ITS alone or in F12.ITS with DMSO (the diluent for retinoic acid). After 7 d the explants were retrieved, freeze-dried, vapor-fixed, and embedded in resin. Endocrine cell types were identified by immunocytochemistry. The numbers of insulin cells were expressed as a proportion of the sum of insulin plus glucagon cells. Retinoic acid had a dose-related effect; the proportion of insulin cells in explants treated with the lower dose of retinoic acid (10−6M) was more than twice the proportion of insulin cells in explants treated with the higher dose (10−5M) of retinoic acid and more than three times that of the control grafts.

A short account of metastatic bone disease

In adults, bone is the preferential target site for metastases from primary cancers of prostate, breast, lungs and thyroid. The tendency of these cancers to metastasize to bone is determined by the anatomical distribution of the blood vessels, by the genetic profile of the cancer cells and by the biological characteristics of the bone microenvironment that favour the growth of metastatic cells of certain cancers.Metastases to bone may have either an osteolytic or an ostoblastic phenotype. The interaction in the bone microenvironment between biological factors secreted by metastatic cells, and by osteoblasts and osteoclasts, and the osteolytic and osteoblastic factors released from the organic matrix mediate a vicious cycle characterized by metastatic growth and by ongoing progressive bone destruction. This interaction determines the phenotype of the metastatic bone disease.