Endocrine and sperminogenic testicular function. 8. Relationships between testicular and plasma testosterone concentrations as well as between the number of Leydig cells in testicular tissue and their cell nucleus volume in boars of different ages]

Testicular tissue and blood samples (V. spermatica interna) were taken from 32 boars during castration. The animals were different age groups. Against this background, studies were conducted into the correlations between testicular and plasma testosterone, on the one hand, and the amount of interstitial cells of Leydig in testicular tissue as well as the latters' cell nuclei volumes, on the other. The results seemed to support the conclusion that any age-dependent increase of testicular and plasma testosterone concentrations was caused unambigously by an absolute increase in volume of androgenic testicular tissue, in concomitance with testicular growth, in other words, by rise in the total number of interstitial cells of Leydig.     

Multiple drug resistance in Pasteurella multocida and Pasteurella haemolytica from cattle and swine.

The results of antimicrobial susceptibility testing on 262 strains of Pasteurella multocida and 141 strains of Pasteurella haemolytica isolated from cattle and swine from 1971 to 1974 were analyzed for patterns of resistance to streptomycin, penicillin, tetracycline, and chloramphenicol, using a modified Kirby-Bauer procedure. Resistance was recorded for 80.5% of the isolants of P multocida and 92.2% of those of P haemolytica. Resistance to streptomycin was most frequent, followed by resistance to penicillin and tetracycline. Most cultures of P multocida and P haemolytica were susceptible to chloramphenicol. There were 9 patterns of resistance with the aforementioned antibiotics. The combinations, streptomycin and penicillin and streptomycin and tetracycline, each accounted for approximately 10% of the resistance patterns of P multocida. Approximately half of the 14 isolants of P haemolytica were resistant to the combination of streptomycin, penicillin, and tetracycline. These observations underscore the need for antimicrobial susceptibility testing of clinical isolants of P multocida and P haemolytica.     

Termination of pseudopregnancy by administration of prostaglandin F2alpha and termination of early pregnancy by administration of prostaglandin F2alpha or colchicine or by removal of embryo in mares.

At day 24 of gestation, pregnant mares were allotted to 1 of 5 treatment groups (3 to 5 mares/group): group A--nontreated controls; group B--intraembryonic injection of 4 mg of colchicine on day 24; group C--removal of embryo on day 24; group D--subcutaneous injection of 1.25 mg of prostaglandin F2alpha (PGF2alpha) on day 32; and group E--removal of embryo on day 24 and subcutaneous injection of PGF2alpha on day 32. In all mares treated with colchicine (group B), the fetal bulge was absent within 2 days. The interval from injection of colchicine to onset of estrus was very short (mean, 4 days). These results indicated that treatment with colchicine was lethal to the 24-day embryo, and pseudopregnancy did not occur. Surgical removal of the embryo (group C) resulted in pseudopregnancy characterized by a prolonged interval from treatment to return to estrus (mean, greater than 31 days), prolonged production of progesterone, and prolonged maintenance of tense uterine and cervical tone. The interval from treatment to ovulatory estrus was longer (P less than 0.05) for group C mares than for group B mares. The mean interval from treatment to complete loss of tense tubular uterine tone was not significantly different between group A pregnant controls (28.3 days) and group C pseudopregnant mares (30 days). Treatment of pregnant mares (group D) with a single injection of PGF2alpha on day 32 resulted in loss of pregnancy in 4 of 4 mares within 2 to 5 days, and in all group D mares a large decrease in progesterone concentration occurred on day 33, 34, or 35. Although subsequent reproductive activity was variable, all group D mares rapidly lost the tense uterine and cervical tone characteristic of early pregnancy. These results indicated that a single subcutaneous injection of 1.25 mg of PGF2alpha caused loss of pregnancy, and pseudopregnancy did not occur. Treatment of group E mares, which had been made pseudopregnant by removal of embryo, with 1.25 mg of PGF2alpha resulted in termination of pseudopregnancy in 5 of 5 mares. All group E mares returned to estrus within 2 to 5 days after treatment, and progesterone concentration decreased (P less than 0.05) within 2 days after treatment. There was no significant difference in loss of tense tubular uterine or cervical tone between pregnant (group D) and pseudopregnant (group E) mares after PGF2alpha treatment.     

Colony Formation in Culture by Bovine Granulopoietic Progenitor Cells

Calf bone marrow cells cultured in a semi-solid medium of 0.8% methyl cellulose produced colonies of granulocytic cells and macrophages by seven days. A prerequisite for colony growth was the presence of serum obtained from a calf three hours after intravenous injection of endotoxin. Three morphological types of colonies were seen but cell types within these types of colonies did not differ. Cultured cells were identified by morphological and cytochemical characteristics.

Optimum growth occurred when serum from endotoxin stimulated calves and fetal calf serum were present in a volumetric ratio of 7:3. Inhibition of colony growth occurred when endotoxin-stimulated serum was present at greater than optimum concentration. Normal calf serum, fetal calf serum, mouse L-cell conditioned medium and bovine urine did not stimulate significant colony growth when 8.0 x 10⁴ marrow cells were cultured.

There was a linear relationhip between the number of marrow cells in the cultures and the number of colonies produced. Colony forming efficiency ranged from 13 to 59 colonies per 10⁵ cells plated.

The behaviour of calf colony forming units in suspension culture was similar to that reported for mouse colony forming units.