Testicular Ultrastructure of Zebu Bulls in Costa Rica

Abstract

Summary The testicular ultrastructure of sexually mature Zebu (Bos indicus) bulls from Costa Rica was studied in relation to their classification based on andrological examinations undertaken in the field. Based on the testicular consistency at palpation, each bull was assigned to one of three groups, ranging from normal (Group A) to markedly reduced testicular consistency (Group C). The ultrastructure of the clinically normal testicle (Group A) in the Zebu bull resembled that of Bos taurus. In testicles with a slight to moderate reduction of testicular consistency (Group B) degenerated primary spermatocytes and spermatids were common at all stages of the seminiferous cycle. Abnormalities in the condensation of the chromatin, acrosomal defects, and the presence of degenerated cells and cellular debris were the most common of disturbances found. In testicles from bulls with a marked reduction of testicular consistency (Group C) the seminiferous epithelium of most tubules showed degenerative changes, thereby making it impossible to classify the stage of the cycle. The changes were mainly restricted to spermatocytes and spermatids, whose relative numbers were reduced. The number of cells undergoing meiotic divisions was also greatly reduced. Changes in the spermatids were also found including the appearance of severe acrosomal defects, such as acrosomal pouches, the failure of nuclear elongation and clear defects in chromatin condensation. The present ultrastructural findings in Bos indicus do not differ from the picture of normal testicular structure and of testicular degeneration usually found in Bos taurus bulls.

Morphological Features of the Seminiferous and Cauda Epididymides Epithelia of Breeding Zebu Bulls with Normal and Decreased Testicular Consistency.

“…The lack of degenerative changes at the spermatogonial level in bulls with reduced TC corresponds with results indicating that primary spermatocytes and spermatids were the main type of cells affected in this pathology, in contrast to the spermatogonia which are more resistant to these changes in the bull [5,12,[16][17][18].…”

“…Although changes in TC seemed to be related to the degree of alteration in the testicular parenchyma, as previously determined [5], some of the bulls in this study with slightly reduced TC had a normal histology in most respects. This is not surprising since testicular palpation is a subjective method for determining TC, and variations in scrotum thickness or edema can confound the findings.…”

“…Bulls with a decreased TC are suspected of having a diminished testicular function and are usually considered unfit for breeding. In a previous study, a significant negative relation between decreased TC and the prevalence of abnormal sperm heads in the ejaculate of Zebu bulls and crosses was established [5]. This fact suggested that that testicular consistency could be related to the structural integrity of the seminiferous epithelium.…”

“…A decrease in TC is commonly found in connection with acute or sub-acute testicular pathologies, such as testicular degeneration. Attempts to establish a relation between TC and seminal or fertility parameters of Bos indicus bulls have been inconclusive thus far [1,4], although morphological alterations of the seminiferous epithelium were more frequent in Zebu breeding bulls with low TC than in control bulls [5] and were often associated with temperature-induced testicular pathologies [6]. For Bos indicus, Bos taurus and crossbred breeding bulls extensively reared in Costa Rica, a negative relationship was found between decreased B mating.…”

Efeitos da Insulação Escrotal sobre a Biometria Testicular e Parâmetros Seminais em Carneiros da Raça Santa Inês Criados no Estado do Ceará

“…O retorno à consistência normal das gônadas coincidiu com a elevação gradual da concentração espermática. A diminuição na consistência do parênquima testicular está associada a uma redução na produção de espermatozóides (COULTER e FOOTE, 1979) e maior número de espermatócitos e espermátides degeneradas em todos os estágios do ciclo da espermatogênese em touros (MULLER et al, 1992). Alterações na motilidade progressiva individual e vigor dos espermatozóides surgiram mais rapidamente do que aquelas observadas na concentração espermática e medidas testiculares.…”