Fetal rabbit head

Fig. 3. Montage of 1.0 mm contiguous slices from a single fetal rabbit head, acquired in parallel as part of a group of five and segmented out using Imaged software.

The use of magnetic resonance imaging of the fetal rat and rabbit head, as an alternative to the traditional methods of fixation and preparation of serial sections, is described. Labeled magnetic resonance images of normal head anatomy have been provided as a reference for use when evaluating the internal structures of... 

Evaluation of the internal structures of the fetal rat and rabbit head has traditionally been performed after fixation, most commonly in Bouin s fluid, by assessing serial coronal sections, prepared using a freehand blade to cut the specimen (1, 2). Whilst this method is widely accepted, both by users and regulatory authorities, it does have major drawbacks that are often overlooked because of its widespread use. These include ... 

In addition when it is necessary to process a large number of specimens per day, taking hours over a single specimen is clearly not a practical approach. The use of MRI to examine fresh, unfixed fetal rat and rabbit heads from embryo-fetal development (EFD) studies has already been proposed (6) (see Note 1) and the compromise between image quality and speed of acquisition that is necessary under these circumstances examined. MRI is now considered to have the potential to be an acceptable alternative to current methods after throughput was increased by scanning multiple specimens in parallel with careful optimization of scan parameters. 

Following decapitation, the fetal rabbit and rat heads were placed in a custom-built holder comprising 5 and 14 tubes. 

Pesticides accumulate in fetal cells and reproductive organs in mammals, birds, and fish due to biochemical processes. This is noted especially often for OCPs, which were observed in large amounts (up to 6.8 mg/kg) in, for example, the sexual organs of hares, rabbits, pheasants, green-winged teals, and in white-eyed and red-headed ducks. They were found in animal embryos, as well as in black thrush eggs and in pheasant embryos and amniotic fluid (up to 73.0 mg/kg) [3]. 

With both techniques, the heads of one-half of the fetuses can be fixed in Bourn s fixative for subsequent freehand sectioning and examination. A common artifact induced by fixation in rabbit fetal heads is retinal folding. 

The fetuses are then examined. Full details of fetal examination are provided in other chapters of this book some techniques are performed on fresh fetuses, while other techniques require prior fixation of the fetuses. For rodents, one half of the fetuses in each litter should be examined for soft tissue (visceral) changes the remainder should be examined for skeletal changes. Rabbit fetuses should be examined for both soft tissue and skeletal abnormalities the heads from half of the fetuses should be examined by serial sectioning, with skeletal examination conducted on the remainder of the fetus. 

Historical control data for embryo-fetal studies at Ricerca Biosciences with KBL NZW Rabbit fetal fixed soft tissue examination of head... 

This technique is required for any embryo-fetal developmental toxicity in the rat, mouse, rabbit, or minipig. Caesarean sections are performed on dams before birth. Fetuses are removed and examined externally. Further examinations are then performed to examine internal soft tissues (see Chapters 19 and 20) and skeleton. Fetuses intended for skeletal examinations are eviscerated and the carcasses are fixed. The Alizarin Red S staining process requires several days. The meticulous examination involves the examination of each fetal in a specific order starting from the head to the tail, with the fetus in ventral and dorsal positions. 

This chapter descrihes the method used for serial sectioning and soft tissue examination of the Bouin s fixed fetus (mainly whole rat and or mouse fetuses or rabbit fetal heads) for the assessment of developmental and structural abnormalities. Fetuses are examined externally, together with the internal structures of the head as well as the thoracic and abdominal organs. 

Van Julsingha EB, Bennett CB (1977) A dissecting procedure for the detection of abnormalities in the rabbit fetal head. In Neubert DHJ, Marker HJ, Kwasigroch TE (eds) Methods in prenatal toxicology. University of Chicago, Chicago, IL, pp 126-144... 

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