Tubular contents of equine dentin: a scanning electron microscopic study

The dentinal tubules of 20 permanent equine incisors were investigated by scanning electron microscopy. Occlusal surfaces and longitudinal fracture planes of both etched and undecalcified teeth were examined. Three different types of structure were observed inside the dentinal tubular lumen. Odontoblastic processes could only be visualized in the circumpulpal parts of the tubules. The more peripheral parts were empty or housed cylindrical structures that probably correspond to the laminae limitantes. Collagen fibres were frequently observed in the tubular lumina and were most numerous in the circumpulpal parts of the tubules.     

Erratum

This study describes the localization of progesterone receptors (PR) in the bovine ovary. Ovaries were obtained from 11 non‐pregnant and two pregnant cows. Progesterone receptors were visualized by immunohistochemistry on paraffin sections. Nuclear staining for PR was observed in cells of the follicles, corpora lutea, theca layers, surface epithelium, tunica albuginea, and in superficial and deep stroma cells. No staining was noticed in apoptotic bodies of atretic follicles. Expression of PR in follicle cells indicates an intrafollicular role of progesterone. The higher expression in thecal cells compared with follicle cells indicates that thecal cells mediate some effects of progesterone on the follicular development. Superficial stroma cells showing high expression might have a similar influence on primordial and primary follicles. In general, luteal cells had a lower expression than follicle cells, which may be explained by the down‐regulatory effect of locally produced progesterone. The lower expression in luteal cells during pregnancy can be due to the longer life span of this corpus luteum and concomitant degeneration of its PR. The high and rather constant expression of PR in cells of the surface epithelium remains to be elucidated.     

Prenatal development of the caudal vena cava in mammals: review of the different theories with special reference to the dog

Several items of the development of the caudal vena cava in domestic animals are still controversial. In particular, the origin of the lumbar segment of the caudal vena cava is equivocally described. According to different theories it originates from the right-sided supracardinal, caudal cardinal, sacrocardinal, lateral sympathetic or subcardinal veins. In this review, all five theories are compared with each other and discussed in the light of anatomical variations observed in eight dogs. Species-specific diversity, erratic observations because of technical artefacts, and biased interpretation of the original data are three major reasons for the dissimilarity between the five theories, but they cannot explain all differences. Further studies by using modern techniques such as microvascular corrosion casting and non-invasive three-dimensional microtomography are necessary to better understand the normal development and to explain the variations in domestic animal species.     

Two cases of brachymelia in cats

In this report, two cases of brachymelia in related neonatal cats are described. The malformations are described in view of normal limb development, which is illustrated by scanning electron microscopic images. Hypoplasia and aplasia of the distal limb segments were the main disorders in both kittens. Additional malformations in the second case included fusion of the radius and ulna, congenital patella luxation and a shortened tail. Brachymelia and similar cases of feline dysmelia are poorly documented in the existing literature. Possible causes and terminology of these developmental deformations are discussed.