Organization and seasonal quantification of the intertubular compartment in the bat Molossus molossus (Pallas, 1776) testis

Abstract

Environmental factors can influence the reproductive rates in bats, and since morphometric information of bats testis is scarce, we aimed to compare the organization and quantification of the intertubular components in the testes of the bat Molossus molossus, collected in different seasons. Testicular histological sections were evaluated using light and electron microscopy. The intertubular compartment occupied an average 10% of the testes, being predominately constituted of Leydig cells (LC). The percentages of the testes occupied by the intertubular compartment and by LC were significantly higher in summer, while the other intertubular components did not vary significantly among the seasons. As suspected under light microscopy, the ultrastructural analysis confirmed the existence of multinucleated LC during winter. The increase in the nuclear percentage of LC in winter seems to have caused the decrease of the cytoplasmatic measurements in that season, as well as in the volume of LC. The highest cytoplasmatic values and volume of LC registered in the spring, summer, and fall can be related to greater activity of this cell in these seasons. The higher investment in intertubular tissue and in LC observed in summer, compared to winter; suggest an increase in the steroidogenic capacity of this bat during summer. The analyses correlating testicular morphometry and abiotic environmental factors in this study confirm the influence of climatic factors on the reproduction of M. molossus.

The spermatogenic process of the common vampire bat Desmodus rotundus under a histomorphometric view

“…lilium [28], however higher than in Myotis levis [35] and within the recorded for other mammals [22, 29–33]. The Leydigosomatic index was similar to that observed in other bats and higher than the observed in larger animals [21, 27, 28, 30, 32, 33]. …”

“…In vampire bat, the percentage of Leydig cells was lower compared to frugivorous and insectivorous bats and consequently the percentage of lymphatic space was larger [21, 27, 28], yet within the numbers reported for other mammals [22, 29–33]. The larger investment in Leydig cells found in bats might also be associated to their reproductive behavior, as high levels of testosterone would be required for the maintenance of spermatogenesis and male dominance in harem colonies [23, 27, 28]. This steroidogenic capacity is reinforced by the large number of mitochondria in their cytoplasm, being that the shape of this organelle frequently varies from spherical to elongated or tubular in steroidogenic cells [34].…”

“…molossus [27] and in S . lilium [28], however higher than in Myotis levis [35] and within the recorded for other mammals [22, 29–33].…”

Structure, histochemistry and seasonal variations of the male reproductive accessory glands in the Pallas’s mastiff bat, Molossus molossus (Chiroptera: Molossidae)

“…It is the most common bat in the urban areas of Brazil. It is known to be polyestric with two annual reproductive breeding seasons in Brazil, one in March-April and another in November, and sexually active males are found almost year round (Fabián and Marques 1989;Beguelini et al 2010Beguelini et al , 20122013a;Morais et al 2012Morais et al , 2013. However, information about the reproductive process in males is still scarce.…”

Seasonal assessment of the reproductive cycle and energy reserves of male batsSturnira lilium(Chiroptera: Phyllostomidae)

“…Similarly, no differences were observed for the number of Leydig cells in the testis or per gram of testis in animals captured during either season. Taking both seasons together, the number of Leydig cells per gram of testis in S. lilium was greater than that observed in M. molossus and A. lituratus (Miranda 2012;Morais et al 2013b).…”