Stereological and morphological analysis of the effects of aging on spermatogenesis in rat testis

Abstract Purpose: To quantify, through stereological and morphometric analysis, spermatogenesis in rats undergoing the natural aging process. Methods: Seventy-two male Wistar rats were divided into 6 equal groups according to age at the time of killing: 3, 6, 9, 12, 18, and 24 months. All the rats were subjected orchiectomy and collection of testicular parenchymal fragments for histological and morphometric analysis. The numerical density of spermatids was calculated using a stereological study, and morphometric analysis was conducted to measure the height of the germinal epithelium and the area of the seminiferous tubules. Results: We found that the 18 and 24 months groups showed a significant reduction in the number of round spermatids. However, the height of the germinal epithelium was not significantly different between the groups. The area of seminiferous tubules was also significantly reduced in the elderly rats compared to that in the young ones. Conclusion: Aging of rats showed a significant reduction in the number of round spermatids and the area of the seminiferous tubules, more pronounced in the rats at 18 and 24 months of life.

Estructura testicular y calidad seminal en ratones seleccionados por peso / Testicular structure and semen quality in mice lines selected for weight

La capacidad reproductiva femenina se modificó como consecuencia de la selección de peso realizada en un par de líneas de selección divergente durante 50 generaciones (s: bajo peso; s': alto peso), originadas a partir de una población testigo (t) de ratones CF1 y criadas en la Facultad de Ciencias Veterinarias (UNR). Se probó la existencia de diferencias reproductivas atribuibles al genotipo paterno observadas en el tamaño de camada al nacimiento y en los días transcurridos desde el ingreso a servicio hasta la parición. Con el propósito de explicar las diferencias se comparó la estructura testicular - peso testicular (PTEST), diámetro del túbulo seminífero (DTS), altura de su epitelio (AES) - y la calidad seminal - número de espermatozoides (NE), porcentaje de células anormales (AN), motilidad y desplazamiento de las células espermáticas (Parámetros CASA) -, en machos adultos de 10 a 14 semanas de edad. Se estimó el promedio del DTS y AES en 100 túbulos seminíferos por individuo. El semen se obtuvo de la porción caudal de los epidídimos y de los conductos deferentes. El recuento de espermatozoides se realizó en cámara de Neubauer hemocitométrica y el porcentaje de células anormales se calculó sobre 100 espermatozoides por extendido. Los parámetros de motilidad se determinaron con analizador computarizado de semen Ceros 12.1. La selección por peso diferenció significativamente a las líneas en el mismo sentido de la selección practicada para PTEST, AES y NE. Los machos de la línea más pesada (s') presentaron PTEST y AES mayores y tuvieron un mayor número de espermatozoides al compararlos con los de las líneas s y t (p<0,05). La calidad del semen, bajo las condiciones del setup utilizado, fue similar para los machos de las tres líneas. Por lo tanto, la calidad del semen no aportó a la explicación de las diferencias de fertilidad masculina entre las líneas.

Reproductive female capacity was affected by the genetic selection performed in a pair of lines of two-way selection of body weight for 50 generations (s: downward selection; s': upward selection). These lines were originated from a control CF1 mice population (t) at the Faculty of Veterinary Sciences (UNR). The existence of reproductive differences attributed to the male genotype in the litter size and in the interval from the service beginning to first parturition was proven. With the aim of explaining them, the testicular structure - testicular weight (PTEST), vas deferens diameter (DTS), epithelium height (AES) - and the semen quality - spermatozoa number (NE), abnormal cell percentage (AN), motility and movement of spermatic cells (CASA parameters) were compared, in adult males between 10 and 14 weeks of age. The means of the DTS and AES were estimated for 100 seminiferous tubules per individual. Semen was obtained from the caudal portion of the epididymides and vasa deferentia. Sperm count was performed in Neubauer hemocytometer and abnormal cell percentage was estimated over 100 spermatozoa per sample. Motility parameters were determined with a Ceros 12.1 semen computerized analyzer. Body weight selection occasioned significant differences between lines in the same way of the selection performed for PTEST, AES and NE. Males of the heaviest line (s') show heavier testicles, higher seminiferous epithelium and, consequently, a higher number of spermatozoa when compared with s and t males (p<0,05). Semen quality under the employed setup conditions was similar for males of the three lines. Therefore, semen quality does not contribute to the explanation of the fertility differences between lines.

Sperm ultrastructure and spermatogenesis in the lizard, Tropidurus itambere

Spermatogenesis, with emphasis on spermiogenesis, is described for the lizard, Tropidurus itambere, using light microscopy, phase contrast and epifluorescence, as well as scanning and transmission electron microscopy. Cellular differentiation involves events of chromatin condensation, nuclear elongation and the formation of structural complexes, such as the acrosomal and axonemal ones. Other new characteristics, exclusive for this species, include various aspects of the subacrosomal granule, the insertion of the pro-acrosomal vesicle and the development of these structures to participate in the acrosomal complex. Radial projections occurjust above the nuclear shoulders, which have been recognized already from the beginning of cellular elongation. The development of the midpiece, the dense bodies, formation of the flagellum and elimination of residual cytoplasm result in the final characterization of the mature spermatozoon. Comparisons between Tropiduridae and other lizard families are made.

Morphological study of the spermatogenesis in the teleost Piaractus mesopotamicus

The spermatogenesis of Piaractus mesopotamicus was investigated under light and transmission electron microscopy. The specimens were captured from their natural environment (Rio Miranda and Rio Aquidauana, Pantanal Matogrossense, Brazil) during April and September. The results were compared with the spermatogenic data of specimens under captivity condition. In both conditions, P. mesopotamicus presented the typical spermatogenesis pattern of the teleost fishes, showing no significative differences. The spermatozoon was classified as type I, which has a globular head without acrosome, a short middle piece and a long tail constituted only by the flagellum. This type of spermatozoon is considered the basic type in fishes.

Variaciones del funcionamiento testicular en Octopus mimus adultos / Testicular function variations in adult Octopus mimus

Octopus mimus macho madura precozmente. En general, sobre 200 g son maduros y permanecen en dicha condición hasta la muerte. En consideración a que no hay antecedentes de la fisiología testicular de los machos adultos, fueron estudiadas la función gamética mediante análisis histológico de los túbulos seminíferos y la función endocrina, cuantificando en el testículo, progesterona y testosterona, en conjunto con el crecimiento y funcionalidad de los órganos blancos del andrógeno. Se detectaron tres categorías de machos adultos: maduros jóvenes, de madurez máxima y en regresión. Los animales en regresión producen menor cantidad de ambas hormonas y muestran regresión de la función espermatogénica. La declinación de ambas funciones del testículo indica el estado de envejecimiento de Octopus mimus. Por el contrario, los que están en máxima madurez tienen la mayor capacidad espermatogénica y androgénica, en conjunto con el mejor funcionamiento de las glándulas reproductivas anexas, cualidades que podrían ser consideradas en las normativas de manejo y futuras actividades de cultivo de la especie.

Gonado-modulatory effects of high humidity is pineal dependent in Indian palm squirrel Funambulus pennanti (Wroughton).

F. pennanti presented a clear biphasic pineal mediated seasonal sexual cycle. This sexual cycle was essentially characterised by a very short period of sexual quiescence with an arrest of spermatogenesis during October-November. A small but clear decrease in sexual activity was also observed during March-April. This decrease in sexual activity, however, had no quantifiable effect on spermatogenesis. Sexual recrudescence was observed from December-January. The testes remained sexually active from January till September. Almost an inverse relationship was observed between pineal and testicular weight. Pinealectomy, however, prevented naturally induced gonadal regression during both the periods, i.e. September-November and February-April. Exposure of animals to high RH (80 +/- 4%) during sexually active phase induced a steep regression in testicular weight of sham-operated animals even in the presence of gonad stimulatory long photoperiod (16L:8D) and high temperature (40 degrees +/- 5 degrees C) while exposure of animals to moderate RH (65 +/- 5%) during sexual regression phase partially prevented testicular regression even in presence of inhibitory short photoperiod (11L:13D) and normal environmental temperature (30 degrees +/- 5 degrees C). Pinealectomized animals, neither exhibited testicular regression in February-March nor had involuted testes in September-October, thus, suggesting that the effect of humidity is mediated via the pineal gland.