Pieter Cornillie

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.

Localization of Oestrogen Receptors Within Various Bovine Ovarian Cell Types at Different Stages of the Oestrous Cycle

In the present study oestrogen receptor α(ERα) and oestrogen receptor β (ERβ) mRNA were localized in various ovarian cell types of 23 cows at different stages of the oestrous cycle. ERα was detected by immunohistochemistry and the localization of ERβ mRNA was examined using in situ hybridization. The immunostaining of ERα was low in the ovarian follicles, tunica albuginea and surface epithelium, but high in cells of the deep stroma and superficial stroma, which indicates a functional role of ERα in the cells surrounding the follicles. In contrast, ERβ mRNA scores were low to moderate in primordial and primary follicles, and increased with the development of the follicle. ERβ mRNA scores were higher in cystic follicles than in obliterative follicles. In the corpora lutea and corpora albicantia the scores for ERβ mRNA were moderate. Furthermore, in the corpora lutea, ERβ mRNA levels showed cyclic variations and were low during early dioestrus. The correlation between plasma progesterone levels and the score for ER was low and negative in all ovarian cell types. This study demonstrates the predominant role of ERβ over ERα in bovine ovarian structures. Furthermore, the colocalization of both ERβ mRNA and ERα in most cell types suggests possible interactions between both ER subtypes.

Retrocaval ureter in a cat

THE occurrence of a retrocaval ureter is a well-known condition of clinical relevance in human beings (Bass and others 2000), and has also been experimentally induced in rabbits (Scortichini 1986). In human medicine, cases of a retrocaval or circumcaval ureter have a reported prevalence of 0·1 per cent at postmortem examination, with a three-fold male predominance (Singh and others 2001). The anomaly almost always occurs on the right side (Bass and others 2000), except for specific situations such as situs viscerum inversus, a genetic defect characterised by left-right inversion of asymmetric organs (Brook 1962, Mitchell and others 2003) and persistence of the left inferior vena cava (Gramegna and others 2003), in which a left retrocaval ureter can occur. In 20 per cent of cases, a retrocaval ureter is associated with other congenital defects such as hypospadia, supernumerary lumbar vertebrae, syndactylism and other abnormalities mainly of the cardiovascular or urogenital systems (Perimenis and others 2002, Friebel and others 2004). In human beings, most of these malformations remain asymptomatic (Friebel and others 2004). Clinical manifestation of pathology related to retrocaval ureter usually occurs in the third or fourth decade of the patient’s life, although some exceptional cases have been described in children (Kakanou and others 2001, Soundappan and Barker 2004). Symptoms are due to ureteral obstruction and the resulting hydronephrosis (Uthappa and others 2002). They include abdominal pain in the right flank, recurrent urinary infections, haematuria in varying degrees, urolithiasis and hypertension (Bass and others 2000, Kakanou and others 2001, Uthappa and others 2002, Soundappan and Barker 2004). Diagnosis can be made by an intravenous urogram, which demonstrates a medially deviated, inversed ‘J’-shaped or ‘S’-shaped ureter, with varying degrees of hydronephrosis (Soundappan and Barker 2004). Computer tomography and magnetic resonance imaging can also be used to diagnose clinical and asymptomatic cases of a retrocaval ureter (Uthappa and others 2002). Significant obstruction of the retrocaval ureter requires surgical correction. Transperitoneal laparotomy or laparoscopy is performed, and the ureter is sectioned, relocated in its normal anatomical position and sutured by end-to-end anastomosis (Gramegna and others 2003, Soundappan and Barker 2004). In many cases, the retrocaval segment of the right ureter is stenotic or hypoplastic and must be resected (Kakanou and others 2001). Severe hydronephrosis requires nephrectomy (Soundappan and Barker 2004). This short communication describes a rare case of retrocaval ureter in a cat. During routine dissection for educational purposes at the Department of Morphology, Faculty of Veterinary Medicine, Ghent University, a retrocaval ureter was found in an adult, entire male cat (Fig 1). The anomaly was characterised by a medial deviation of the right ureter, which crossed the caudal vena cava dorsally at the level of the fifth lumbar vertebra. The right ureter subsequently emerged between the caudal vena cava and the abdominal aorta, and coursed back in a lateral direction across the ventral surface of the caudal vena cava. It resumed its normal anatomical location along the psoas musculature, and continued caudally towards the urinary bladder. Neither a dilation of the proximal part of the right ureter nor apparent signs of urinary tract inflammation were present. The animal was thoroughly checked for other urogenital, skeletal and cardiovascular congenital malformations, but none was found. No antemortem clinical information was available for the animal. b