Studies on the mechanism of the ovulation-inhibiting effect of 19-norsteroids in cyclic rats.

Experiments performed in cyclic female rats demonstrated an equal ovulation-inhibiting activity of the 19-norgestagens norethynodrel, lynestrenol and norethisterone acetate after injection in oestrus and metoestrus, and after daily administration from oestrus to pro-oestrus. The results furthermore show that, after application of the minimal ovulation-inhibiting doses during oestrus and metoestrus, these substances 1. induce an increase in prolactin secretion, 2., with the exception of norethisterone acetate, possess a hypophysial site of action, 3. are able to induce deciduoma formation following traumatization of the uterus, and 4. maintain the reactivity of the cyclic corpora lutea to the injection of prolactin. The findings suggest that the prolactin-releasing and luteotrophic action of the progestagens studied may form an essential part of the mechanisms that are responsible for the inhibition of ovulation observed in rats after administration over one cycle.     

Bovine and ovine leukemia viruses. I. Characterization of viral antigens.

A comparative study on several virus-specific antigens of bovine and ovine leukemia viruses is presented. In addition to the major immunologically reactive, nonglycosylated antigen p21, which has a molecular weight of 21,000, both viruses share two glycoproteins of apparent molecular weights of 60,000 (gp60) and 32,000 (gp32), respectively. Immunological cross-reaction suggests that ovine and bovine leukemia viruses are genetically highly related.     

Das nervensystem der gattung Polystomoides ward, 1917 (Monogenea)

The nervous systems of three species of Polystomoides are described. Methods of staining the nerves in trematodes and the relationship of the three trematode groups Digenea, Aspidogastrea and Monogenea are discussed.

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Für technische Hilfe danke ich Miss LiLian Lim, Mr. Teh Kok Leng und Mr. K. Balahrishnan. Durchgefnhrt im Zoology Department, University of Malaya, Kuala Lumpur, mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Morphological reinvestigation and phylogenetic relationship of Acanthobdella peledina (Annelida,Clitellata)

Summary In recently collected specimens of Acanthobdella peledina the nervous system, the genital organs and the coelomic organisation were reinvestigated after complete serial sections. These anatomical results are schematically represented. In addition, the integument, the chaetae and the peripheral muscle layer were investigated by electron microscopy. In general, the results confirm Livanow's classic monograph (1906), with the exception of a few details. The body apparently possesses neither a prostomium nor an achaetous buccal region (peristomium). The number of 29 true segments is concluded from the number of segmental ganglia. The five anteriormost segments, each with four pairs of hookshaped chaetae arranged around the mouth opening, are considered to be functionally equivalent to an anterior sucker. The ultrastructure of the integument and the chaetae generally conforms to the typical annelidan pattern. The muscle cells are of the typical hirudinean type. The outer male genital pore is positioned in segment 10; the female organs open in segment 11 directly behind the septum between segments 10 and 11. The main emphasis is laid on the evaluation of the position of the taxon within the Clitellata, including a discussion of the Branchiobdellida, and the cladograms presented show the Acanthobdellida to be the sister group of the Euhirudinea. Characters shared by the Branchiobdellida and Hirudinea (including A. peledina) are considered to be convergently evolved.