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It is essential to know the timing and process of normal gonadal differentiation and development in the specific species being investigated in order to evaluate the effect of exposure to endocrine-disrupting chemicals on these processes. In the present study gonadal sex differentiation and development were investigated in embryos of a viviparous species of(More)
This study deals primarily with the morphology and ultrastructure of the pronephros in the green toad Bufo viridis during prometamorphosis when the pronephros and the developing mesonephros function simultaneously. Furthermore, the mesonephros was studied during pro- and postmetamorphosis with emphasis on the distal segments of the nephron. The paired(More)
This study deals with the morphology and ultrastructure of the mesonephros in adult caecilians of the species Geotrypetes seraphini. Based on serial sections in paraffin and araldite, nephrons are reconstructed and the cellular characteristics of different nephron segments described. The long and slender mesonephric kidneys of G. seraphini are broadest(More)
The spermatozoan from testes of Cephalothrix rufifrons consists of an elongated, straight head 13–14 μm long with a flattened anterior acrosome and a 12.5-μm-long nucleus. Placed along one side of the nucleus, is a single tubular 7-μm-long mitochondrion. There is no midpiece, but immediately posterior to the nucleus are two centrioles. The tail is at least(More)
A great deal of interest in the element vanadium has been generated recently because of its potential as a therapeutic agent for diabetes mellitus. Vanadium's insulin-mimetic properties and its requirement for proper growth and development suggest that it may be involved in insulin's mechanism of action. We have therefore examined vanadium levels in kidney,(More)
Evidence is discussed that apical CFTR Cl- channels of mitochondria-rich (MR) cells of Bufo bufo skin conduct beta-adrenergic receptor-activated Cl- currents. Ussing chambers studies revealed the following selectivity sequence of the receptor activated conductance, Cl- > Br- > NO3- > I-. With ion selective microelectrode-techniques, it was shown that(More)
  • A Jespersen
  • 1976
The multiplication of bacteria is examined by quantitative culture from the organs of two groups of field voles injected intraperitoneally with a large dose of M. tuberculosis or a small dose of M. bovis and killed at intervals during a period of up to 3 months after the injection. M. tuberculosis given in a dose of 7 X 10(5) viable units did not multiply,(More)
The intertidal Bivalvia Barrimysia siphonosomae (Montacutidae) and Pseudopythina ochetostomae (Kelliidae) live commensally with Siphonosoma cumanense (Sipuncula) and Ochetostoma erythrogrammon (Echiura), respectively. Both bivalves are hermaphrodites although males and females may occur. Paired, pouch-shaped seminal receptacles are located in the(More)
The bivalve Pseudopythina macrophthalmensis (Galeommatoidea) is a commensal with the crab Macrophthalmus convexus (Ocypodidae) in Okinawa Prefecture, Japan. It is a protandric hermaphrodite which incubates the 65-µm large ova in the suprabranchial cavity. The species produces two types of sperm, which were studied with the electron microscope. The(More)