Collecting duct epithelial-mesenchymal transition in fetal urinary tract obstruction.

Renal interstitial fibrosis contributes to the progression of most chronic kidney diseases and is an important pathologic feature of urinary tract obstruction. To study the origin of this fibrosis, we used a fetal non-human primate model of unilateral ureteric obstruction focusing on the role of medullary collecting duct (CD) changes. Obstruction at 70 days gestation (full term approximately 165 days) results in cystic dysplasia with significant medullary changes including loss of the epithelial phenotype and gain of a mesenchymal phenotype. These changes were associated with disruption of the epithelial basement membrane and concomitant migration of transitioning cells presumed responsible for the observed peritubular collars of fibrous tissue. There was an abundance of cells that co-expressed the intercalated cell marker carbonic anhydrase II and smooth muscle actin. These cells migrated through the basement membrane and were significantly reduced in obstructed ducts with peritubular collars. Our studies suggest that fetal urinary tract obstruction results in a CD epithelial-mesenchymal transition contributing to the interstitial changes associated with poor prognosis. This seems restricted to the intercalated cells, which contribute to the expansion of the principal cell population and the formation of peritubular collars, but are depleted in progressive injury.

Parasites of domestic and wild animals in South Africa. III. Oestrus spp. and Gedoelstia hässleri in the blesbok.

Four blesbok culled in the Rietvlei Nature Reserve, Pretoria, District during May 1972 were found to harbour large burdens of 1st instar Oestrus spp. larvae and from 16-37 3rd instar larvae of Oestrus macdonaldi. They were also infested with large numbers of 1st instar Gedoelstia hässleri larvae but only 2 harboured 3rd stage larvae of this species. During an 18-month period 34 blesbok were culled in pairs in the Percy Fyfe Nature Reserve, Potgietersrus District. These antelope harboured peak numbers of 1st instar Oestrus spp. larvae during February, July and December but few if any during early October. Third instar Oestrus variolosus larvae were generally recovered from July-February and those of O. macdonaldi during July 1972 and from May-September 1973. Some 1st instar larvae of these flies appeared to undergo a pulmonary migration before returning to the naso-pharyngeal area to mature. The pupal period of O. variolosus varied from 67 days during the spring to 35 days during the summer. G. hässleri larvae reached peak numbers from October 1972-January 1973 and during May and June 1973. The lowest numbers were recovered from August-October 1973. Recovery and measurement of 1st instar larvae indicated that they either undergo an ocular-cranial or ocular-vascular-pulmonary migration before reaching the naso-pharyngeal area. Pupal periods varied from 46 days for flies hatching during October to 22 days for those hatching during December.

Parasites of comestic and wild animals in South Africa. II. Oestrus ovis in goats.

During a period of 13 months, 130 goats' heads, obtained form the Johannesburg Municipal Abattoir, were examined for infestation with Oestrus ovis. Investation was present in 73,8% of the heads and the mean burden comprised 4,4 larvae. Such a small nuber of larvae were present that no clear seasonal incidence pattern could be determined. Pupal periods could be as long as approximately 60 days for flies hatching during October and May and as short as approximately 24 days for those hatching from December-February. The findings are compared with those obtained from surveys in sheep in south africa.