Development of extra-embryonic membranes and fluid compartments

An account of the development of extra-embryonic membranes in the embryo of poultry. The roles of these membranes in the transfer of water from albumen to yolk and to embryonic tissue is reviewed

Interactive learning in biology with PhotoCD and associated software

This paper describes the pioneering development of flexible‐learning courseware in the teaching and learning of cell biology using a novel optical disk‐based technology — PhotoCD — and its associated computer software. The use of this format in an educational context for the manipulation of, and interaction with, photographic images in electronic form is presented for the first time. Examples of courseware which use PhotoCD, image‐enhancement and image‐management software in biology education are given, and an evaluation by undergraduates in biology education (student teachers) of these teaching and learning strategies is presente

The effect of static incubation on the yolk sac vasculature of the Japanese quail (Coturnix c. japonica)

Static incubation affects early embryonic development with, notably, a reduction area vasculosa expansion and diminished sub-embryonic fluid (SEF) volume, effects produced during a ‘critical’ period (3-7 days in the chick) (Baggott et al., 2002). Also, as noted by Babiker & Baggott (1992), SEF is produced in bulk only after the appearance of the yolk sac vasculature (YSV), which undergoes extensive proliferation before and during the critical period. Quantification of such changes in YSV requires estimates of both the quantity of vessels and the degree of branching. In the chick, total vessel length increased linearly up to 160h of incubation, whereas branching was maximal by about 96 h (Vico et al., 1998); so, by the critical period branching is complete yet vessel growth continues. It would seem likely, therefore, that a lack of turning would reduce both measures of YSV proliferation during the critical period. In quail the effect of static incubation seems not to be simply due to retardation of YSV proliferation, as vascular density index was reduced in unturned eggs in the middle of the critical period, only to increase again by 168 h. Also early in the critical period fractal dimension was 1.70 (as in the chick, Vico et al., 1998), yet then decreased in unturned eggs, although not significantly, and subsequently an increase occurred. Thus during the critical period static incubation specifically affects the structuring of the YSV but whether this is because of, or independent of, retardation of area vasculosa expansion is not known

The pH and ionic composition of the sub-embryonic fluid of the Japanese quail (Coturnix c. japonica)

The current theory of acid-base chemistry regards [H+] as a dependent variable: changes in pH of a fluid can only occur by alteration of strong ion concentrations ([Na+], [K+], [Cl-]). The objective of this study was to determine whether manipulation of sub-embryonic fluid strong ion composition would alter [H+] in the direction predicted by theory. Changes to fluid strong ion concentrations decreased pH in the way predicted and the changes in Cl- suggest a passive distribution. Also, changes in organic anions suggest an essential role for these in acid-base chemistry of this fluid. It was notable that both Na and HCO3- were unaffected by the treatments emphasising the importance of these two ions in fluid production by the quail blastoderm

The use of computer-based assessments in a field biology module

Formative computer-based assessments (CBAs) for self-instruction were introduced into a Year-2 field biology module. These CBAs were provided in ‘tutorial’ mode where each question had context-related diagnostic feedback and tutorial pages, and a self-test mode where the same CBA returned only a score. The summative assessments remained unchanged and consisted of an unseen CBA and written reports of field investigations. When compared with the previous three year-cohorts, the mean score for the summative CBA increased after the introduction of formative CBAs, whereas mean scores for written reports did not change. It is suggested that the increase in summative CBA mean score reflects the effectiveness of the formative CBAs in widening the students’ knowledge base. Evaluation of all assessments using an Assessment Experience Questionnaire indicated that they satisfied the ‘11 conditions under which assessment supports student learning’. Additionally, evidence is presented that the formative CBAs enhanced self-regulated student learning

Learning support for mature, part-time, evening students: providing feedback via frequent, computer-based assessments

A new module in our first year Biology curriculum was used as a vehicle to test strategies for improving learning support. To this end, we have administered frequent CBA, incorporating extensive feedback, both to pace the students’ study efforts and to pinpoint areas in which additional help from lecturers may be required. Three of the 7 CBA provided through the 15-week course were initially given as open-book summative tests, thus contributing to the overall mark for the module. Other CBA were formative: these included repeats of the summative CBA made available for revision purposes, as well as other CBA which focused mainly on aspects of the course that were summatively assessed by other means. A closedbook final exam, also computer-based, was given in the final week as a comprehensive assessment. We have evaluated the utility and effectiveness of our approach by surveying student opinion via questionnaires, examining patterns and extent of student use of formative assessments, and by analysing grades for the summative CBA. We have found the students’ perceptions of the approach to be largely positive and that the formative CBA were well-used, especially as revision aids for the final exam. Our analysis further indicates that the style of the assessments may have been especially helpful to students whose first language is not English

Electrolyte and Water Balance of the Early Avian Embryo: Effects of Egg Turning

Formation of sub-embryonic fluid (SEF) is a key aspect of the physiology of the early avian embryo.Here we review the process of SEF formation and the factors which influence its composition and the rate of SEF production and depletion in the Japanese quail and domestic fowl.There is particular emphasis on the role of turning of the egg during incubation and we briefly consider the broader role of egg turning during avian incubation. The bulk of the review deals with the growth of the area vasculosa of the yolk sac membrane, the cellular processes of SEF formation, and the water and electrolyte physiology of the avian embryo during the first half of incubation.We conclude with a brief discussion of the areas for future investigation