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There is very little information regarding the testis structure and function in domestic cats, mainly data related to the cycle of seminiferous epithelium and sperm production. The testis weight in cats investigated in the present study was 1.2 g. Compared with most mammalian species investigated, the value of 0.08% found for testes mass related to the body mass (gonadosomatic index) in cats is very low. The tunica albuginea volume density (%) in these animals was relatively high and comprised about 19% of the testis. Seminiferous tubule and Leydig cell volume density (%) in cats were approximately 90% and 6%, respectively. The mean tubular diameter was 220 microm, and 23 m of seminiferous tubule were found per testis and per gram of testis. The frequencies of the eight stages of the cycle, characterized according to the tubular morphology system, were as follows: stage 1, 24.9%; stage 2, 12.9%; stage 3, 7.7%; stage 4, 17.6%; stage 5, 7.2%; stage 6, 11.9%; stage 7, 6.8%; and stage 8, 11 %. The premeiotic and postmeiotic stage frequency was 46% and 37%, respectively. The duration of each cycle of seminiferous epithelium was 10.4 days and the total duration of spermatogenesis based on 4.5 cycles was 46.8 days. The number of round spermatids for each pachytene primary spermatocytes (meiotic index) was 2.8, meaning that significant cell loss (30%) occurred during the two meiotic divisions. The total number of germ cells and the number of round spermatids per each Sertoli cell nucleolus at stage 1 of the cycle were 9.8 and 5.1, respectively. The Leydig cell volume was approximately 2000 microm3 and the nucleus volume 260 microm3. Both Leydig and Sertoli cell numbers per gram of testis in cats were approximately 30 million. The daily sperm production per gram of testis in cats (efficiency of spermatogenesis) was approximately 16 million. To our knowledge, this is the first investigation to perform a more detailed and comprehensive study of the testis structure and function in domestic cats. Also, this is the first report in the literature showing Sertoli and Leydig cell number per gram of testis and the daily sperm production in any kind of feline species. In this regard, besides providing a background for comparative studies with other fields, the data obtained in the present work might be useful in future studies in which the domestic cat could be utilized as an appropriate receptor model for preservation of genetic stock from rare or endangered wild felines using the germ cell transplantation technique.

With the use of a digital image-processing method three-dimensional reconstructions of the arrangement of spermatocytes in human seminiferous tubules were performed. With this method it was possible to investigate the cellular distribution in the tubule in nearly any given perspective and projection. In addition, by means of simple mathematical procedures, such as by transformation of Cartesian coordinates into cylindrical coordinates, it was possible to vary the shape of a reconstruction, i.e., to convert the cylindrical image of a tubular portion into a right-angled r-phi-z-representation. The present work not only confirms the existence of a complex helical plan of organization of the human seminiferous epithelium but also provides further aspects of the phenomenon of physiological germ-cell loss and its integration into the kinetics of spermatogenesis.

Testicular tissue and sperm from the cauda epididymidis of 300 boars were obtained in 6 collections during 1 year at a Chicago abattoir. Seventy-five boars (25%) had - 1 sperm abnormality present at rates that could result in infertility. These abnormalities and their frequency criteria were: proximal droplets > or = 15%, loose heads > or = 10%, abnormal middle pieces > or = 10%, abnormal acrosomes > or = 10%, bent tails > or = 15%, coiled tails > or = 15%, and abnormal head shapes > 5%. These 75 abnormal boars were then compared with a control group of 75 boars selected at random from the remaining 225 boars. Frequency of sperm abnormalities, testicular and epididymal weights, relative seminiferous epithelial areas (SEA), and the degree of testicular lesions were used in making comparisons. Testicular lesions were scored on a scale of 1 (normal) to 5. The SEA was measured and was expressed as the mean area of 50 tubules. The SEA was negatively correlated with proximal droplets and abnormal middle pieces in abnormal boars and abnormal head shapes in control boars. The mean SEA was 8.71 and 5.60 cm2 for control and abnormal boars, respectively. The overall mean score for testicular lesions was 1.72 and 3.17 for control and abnormal boars, respectively.