Effect of testicular damage induced by cryptorchidism on insulin-like growth factor I receptors in rat Sertoli cells.

The distribution and density of functional insulin-like growth factor I (IGF-I) receptors in cryptorchid and scrotal rat testes and epididymides during gonadal development were studied. Cryptorchidism was induced by unilateral gubernaculectomy in 4-day-old animals, and organs were studied at 15, 30, 60 and 90 days of age. Tissue membranes were assayed for 125I-labelled IGF-I binding. Characterization and specificity of binding sites showed that both normal and contralateral undescended testes and epididymides exhibited typical type 1 IGF receptors. In normal testes, IGF-I receptor density was 20.6 nmol g-1 wet mass at day 15, and decreased to 12.8 nmol g-1 wet mass at adult age (day 90). Cryptorchid testes showed IGF-I receptor concentrations similar to normal testes at day 15 and day 30, but in postpubertal stages displayed a divergent pattern, with a continuous increase at day 60 and day 90, reaching a higher density than those found for immature ages (62 nmol g-1 wet mass). Both normal and cryptorchid epididymides had a similar concentration and a comparable decrease in IGF-I receptors throughout development. In studies with immunohistochemical techniques (alpha IR-3 antibody), IGF-I receptors were found in primary spermatocytes, Sertoli cells and Leydig cells. Cryptorchid tubules showed a lack of germinal epithelium and a marked increase of immunoreactive IGF-I receptors in Sertoli cells, compared with normal tubules from scrotal testes. Intense immunoreactivity for IGF-I receptors was present in the principal cells of epididymal tubules in both normal and cryptorchid organs.(ABSTRACT TRUNCATED AT 250 WORDS)

Choosing among different technical variations of Percoll centrifugation for sperm selection.

We compared the efficiency of different methodological variations of the centrifugation through discontinuous Percoll gradients (PC) to improve semen samples in the laboratory. Five different combinations of the number, volume and density of PC layers were assayed in 14 semen samples presenting various qualities. Each specimen was divided into five aliquots and processed simultaneously. The percentage of spermatozoa showing optimal movement (VAP > 30 microns s-1 and STR > 80%) after PC selection when the number of gradients was reduced to three or two (PC-3: 43.3%, PC-2: 41.3%) and when the volume of layers was diminished to 0.5 ml (mPC-3: 44.2%, and mPC-2: 48.1%), was higher than in classical columns with four gradients of 1 ml (PC-4: 26.3%). The absolute recovery of optimal sperm was better with PC-2, mPC-2 and mPC-3. In samples showing low concentration or motility of spermatozoa, mPC-2 was the most effective technique. PC-2 and mPC-2 showed a tendency to eliminate more red blood cells contaminating the samples. Straight line velocity and straightness were similarly improved by all the methods. We conclude that the technique of PC centrifugation with only two gradients is simpler and more effective for sperm selection and in cases of poor samples can be used with low-volume layers.

Sperm selection by PD-10 sephadex columns: comparison with SpermPrep filtration and Percoll centrifugation.

The efficacy of a disposable, prepacked column (PD-10) containing Sephadex G-25, to select motile spermatozoa, was compared with another column for sperm filtration (SpermPrep) and centrifugation through Percoll gradients. Aliquots of washed sperm suspensions were processed by the three techniques. The number of motile cells and the proportion of total spermatozoa selected was similar for all methods. Recovery of spermatozoa showing optimal movement was 145.9 +/- 30% (mean +/- SEM) with PD-10 columns and 131.9 +/- 32% with Percoll, both significantly higher than SpermPrep (71.9 +/- 11%; P < 0.05). The straight line velocity of motile cells was lower in samples processed by SpermPrep (29.3 +/- 2 microns/S) compared to both PD-10 (34.7 +/- 1 micron/s) and Percoll (34.9 +/- 2 microns/s; P = 0.07). When whole semen was processed, total sperm recovery with PD-10 was 61.7 +/- 8% versus 47.7 +/- 7% with Percoll (P < 0.001). Percoll centrifugation improved the percentage of morphologically normal spermatozoa more than PD-10. Similar proportions of motile spermatozoa and cells with optimal motility were obtained by both methods. We conclude that PD-10 filtration columns can be used to prepare semen in the laboratory as a practical alternative to other methods.