[The zoological garden of Amsterdam Natura Artis Magistra during world War II].

Thanks to the wise management of its director, dr. Armand Sunier, and his team, 'Artis' survived the difficult war period without great losses of its animals and only material damage to some buildings. Artis has meant very much for the inhabitants of the city of Amsterdam during the war.

Isolation and partial characterization of a lentivirus from talapoin monkeys (Myopithecus talapoin).

We have identified a novel lentivirus prevalent in talapoin monkeys (Myopithecus talapoin), extending previous observations of human immunodeficiency virus-1 cross-reactive antibodies in the serum of these monkeys. We obtained a virus isolate from one of three seropositive monkeys initially available to us. The virus was tentatively named simian immunodeficiency virus from talapoin monkeys (SIVtal).

Daudi supernatant, unlike other H-Y antigen sources, exerts a sex-reversing effect on embryonic chick gonad differentiation.

In vitro cultures of intact chick gonads (organ cultures) and reaggregation cultures of dispersed gonad cells (roller cultures) were made. Gonads or gonad cells from 7-day-old chick embryos, at the stage when sex-specific differentiation begins, were cultured in the presence of presumed H-Y antigen-containing supernatants, or co-cultured in the presence of H-Y antigen-producing cell lines. The H-Y antigen-producing cells tested were of human, mouse, bovine and chicken origin.

[Veterinary education; is it balanced?].

As a professional body, we are continually torn between two alternatives: do we love animals or do we see them as bioindustrial objects, do economics prevail or do ethics, should we specialize or should we retain a broad basis of knowledge? I would like to go further and philosophize about a totally different sort of specialisation - veterinarians who are concerned solely with intensive animal husbandry and veterinarians who are concerned solely with the free-range sector. Could something such as moral specialisation exist?

Ascites in broilers. 1. Experimental factors evoking symptoms related to ascites.

Male broilers of two genetically related stocks with divergent growth rates and feed conversion ratios were used to study metabolic backgrounds on the occurrence of pulmonary hypertension, heart failure, hypoxemia, and ascites in poultry. An experiment with a 2 x 2 x 2 x 2 factorial split-plot arrangement of treatments with 96 groups of 12 broilers was performed. Effects of stock and environmental factors such as ambient temperature, dietary fat, and dietary energy on performance, energy metabolism, oxygen consumption, hematocrit values, and mortality were investigated in broilers from 1 to 5 wk of age.

Influence of claw clipping, stocking density and feeding space on the incidence of scabby hips in broilers.

1. The aetiology of scabby hips was studied in broilers by scratching the skin with chicken claws, clipping the birds' claws and varying the effects of stocking density and food trough allocation. 2.

A case of combined hermaphroditism and autofertilisation in a domestic rabbit.

A true hermaphrodite rabbit served several females and sired more than 250 young of both sexes. In the next breeding season the rabbit, which was housed in isolation, became pregnant and delivered seven healthy young of both sexes. It was kept in isolation and when autopsied was again pregnant and demonstrated two functional ovaries and two infertile testes.

Triploidy and intersexuality in adult commercial layers.

The cause of masculinisation of the left ovary and the outgrowth of the vestigial right gonad was investigated in intersexual hens. Tumour-like cell masses, resembling mouse tubular adenomas of the ovary, were observed in the majority of masculinised left gonads. Except for one male and two intersexuals, testosterone concentrations were below detectable levels.

[Veterinary care and concerns and intensive animal husbandry].

Developments in intensive animal husbandry as well as the reactions called forth by this new form of livestock husbandry in various groups of society and in research workers are reviewed in the introductory part; it was only during the past few years that veterinary medicine in the Netherlands began to concern itself with the negative effects of intensive animal husbandry on animal health and welfare. The practical situation in poultry and pig husbandry is then subjected to a critical analysis. It is concluded from a number of objective observations such as the use of pharmaceutical agents and vaccines and the appearance of particular pathological changes that limits should be imposed on growth.

Endoscopy in birds.

Endoscopic examination is described as a valuable diagnostic method in birds. In the introduction, reference is made to the literature on this subject. Apart from the classical approaches, alternative sites to enter the thoraco-abdominal cavity in birds are discussed.

[Triploidy as a possible cause of intersexuality in chickens (Gallus domesticus)].

A number of cases of intersexuality occurred in a fairly large number of cases in 6-8 months-old laying hens on two poultry farms in the province of Limburg. When macroscopic and microscopic studies failed to supply any evidence concerning the cause of the considerable development of the right gonad, it was decided to do a chromosome analysis. Three intersexes in which the chromosomes were studied, were found to be triploid birds showing a ZZW sex chromosome combination, which aberration may have been the cause of the intersexuality observed.

Spermatogenesis in the boar.

In order to study kinetics of the spermatogenic epithelium in the adult boar, a method has been developed to prepare seminiferous tubules mounted as a whole, after which these tubules have been processed and studied as described previously only for rats, mice and hamsters. The tubules were fixed in Zenker for 24 hours and stained with periodic acid - Schiff - haematoxylin to identify the steps in spermatid development, or by Harris' hemalum to identify spermatogonia and spermatogonial divisions. Spermatid development in the boar is comparable with spermatid development in small laboratory rodents.

The prevention of orchiopexy-induced testicular lesions in the pig.

From previous experiments it was concluded that failure of spermatogenic cells to differentiate after orchiopexy seems to be due to surgical trauma. Furthermore it appeared that in normally descended testes of naturally unilaterally cryptorchid pigs subjected to orchiopexy, the spermatogenic epithelium was poorly developed as compared with that of scrotal testes of unilaterally cryptorchid pigs that had not undergone the surgical procedure. Even simple inguinal surgery in unilaterally naturally cryptorchid piglets may already give rise to severe histological lesions in the spermatogenic epithelium of the normally descended contralateral testes at adulthood.

The influence of elevated testicular temperature and scrotal surgery on the number of gonocytes in the newborn pig.

Morphological changes become apparent shortly after birth in the abdominally located testes of the pig. To test the influence of temperature on gonocyte multiplication, scrotal testes of newborn piglets were subjected to continuous artificial heating. It was found that in the young pig during the first 2 weeks of life when the mitotic activity of the gonocytes is high, they are very sensitive to a combination of elevated testicular temperature and scrotal surgery.

The origin of orchiopexy-induced testicular lesions in the pig.

Cooling experiments of abdominal testes in adult, naturally cryptorchid pigs indicate that spermatogenic arrest in abdominal testes is not due to an inborn defect, but is caused solely by maintenance of the testis at abdominal temperature. It is postulated that failure of spermatogenic cells to differentiate after orchiopexy results from surgical trauma. Evaluation of the orchiopexy procedure revealed that simple manipulation of a normally descended testis may give rise to damage to the spermatogenic epithelium.

Induction of spermatogenesis in the naturally cryptorchid pig.

Abdominal testes of adult, naturally unilaterally cryptorchid boars were subjected to continuous artificial cooling for 5, 15, 25, or 45 days. This treatment initiated development of the spermatogenic epithelium. After a cooling period of 45 days there was complete differentiation in many seminiferous tubules.

[A differential diagnostic abnormality (?) with regard to diarrhoea in calves (author's transl)].

The following article describes the "case-history" of a newborn calf suffering from ordinary calf-diarrhoea. Because the therapy was not successful the animal was examined again. The result was a dichloorvos intoxication caused by a Vaponastrip that was hung up in close contact with the patient.

[Autofertilisation in the chicken (Gallus domesticus)(author's transl)].

It is a well known fact that after removal of the left ovary in the young chicken, the right gonad starts growing and assumes the structure of an immature testis. In the cases reported in the literature active spermatogenesis rarely occurred. To bring autofertilisation of the hen closer to reality, we used ten day-old female embryos, whose gonads were divided between two gonadectomized young animals of different sex.