Embryonic development of lake whitefish Coregonus clupeaformis: a staging series, analysis of growth and effects of fixation.

A reference staging series of 18 morphological stages of laboratory reared lake whitefish Coregonus clupeaformis is provided. The developmental processes of blastulation, gastrulation, neurulation as well as development of the eye, circulatory system, chromatophores and mouth are included and accompanied by detailed descriptions and live imaging. Quantitative measurements of embryo size and mass were taken at each developmental stage. Eggs were 3·19 ± 0·16 mm (mean ± s.d.) in diameter at fertilization and embryos reached a total length (LT ) of 14·25 ± 0·41 mm at hatch. Separated yolk and embryo dry mass were 0·25 ± 0·08 mg and 1·39 ± 0·17 mg, respectively, at hatch. The effects of two common preservatives (formalin and ethanol) were examined throughout development and post hatch. Embryo LT significantly decreased following fixation at all points in development. A correction factor to estimate live LT from corresponding fixed LT was determined as live LT = (fixed LT )(1·025) . Eye diameter and yolk area measurements significantly increased in fixed compared with live embryos up to 85-90% development for both measurements. The described developmental stages can be generalized to teleost species, and is particularly relevant for the study of coregonid development due to additionally shared developmental characteristics. The results of this study and staging series are therefore applicable across various research streams encompassing numerous species that require accurate staging of embryos and descriptions of morphological development.

Rare bone disorder affecting the temporal bone.

Fibrous dysplasia is an uncommon benign disorder of unknown etiology. Rarely, it presents isolated in the temporal bone. We present three cases of monostotic fibrous dysplasia that involved the entire temporal bone.

Migratory foreign body in the neck.

Oesophageal penetration and migration of foreign bodies are fairly rare occurrences. Most reported cases in the literature involve fish bones, which are eventually found in the lateral neck soft tissue or thyroid lobule. We present a case of a migrating fish bone in an elderly female which was found embedded in her right sternocleidomastoid muscle. The fish bone was successfully removed via neck exploration. Appropriate literature is reviewed.

Benign fibrous tumour of the parotid gland.

The case of a 44-year-old man with left parotid enlargement that was initially diagnosed as cementifying fibroma is presented. The lesion was found in the deep lobe of the parotid gland and was successfully removed. Postoperatively, the patient recovered well with intact facial nerve function and remained asymptomatic after 1 year. Subsequent histology revealed the mass to be a benign fibrous tumour. The diagnosis and management of this rare entity are discussed.

Unusual migratory foreign body in the neck.

Reports of ingested foreign bodies penetrating the pharynx and migrating through the neck are rare, and mostly involved fish bones. We describe a 44-year-old man who was involved in a motor vehicle accident and accidentally swallowed his tooth. The swallowed tooth penetrated the pharynx and became lodged adjacent to his right thyroid gland. It was successfully removed via neck exploration and the patient recovered well.

Benign teratoma of the nasal cavity.

A teratoma is a true neoplasm composed of an assortment of tissue often alien to the site from it arises. Teratomas of the head and neck are exceedingly rare and usually present in the neonatal period. Most of these are found in the cervical region and nasopharynx. Though most tumors are benign, they are often malignant with regards to the location. Here we present a rare case of benign teratoma arising from the nasal septum and presenting for the first time in a young adult. Appropriate literature is reviewed.

Aerodigestive amyloidosis presenting as acute asthma.

Aerodigestive amyloidosis is a rare disorder characterized by fibrillar protein deposition in the aerodigestive tree. We present a case of a 19-year-old Chinese gentleman whose diagnosis was initially missed as he presented with features suggestive of severe bronchial asthma and was intubated and ventilated. He subsequently presented 2 years later with severe stridor and required emergency tracheostomy. Current literature is reviewed for the histopathology, common clinical features, radiological findings and treatment options for aerodigestive amyloidosis.