Morphofunctional evaluation of the testicle and the spermatogenic process of adult white-eyed parakeets (Aratinga leucophthalma MULLER, 1776) during the different seasons of the year

Reproductive biology, morphology, and morphometry of ovaries and oviducts of Trachemys scripta elegans in Brazilian Cerrado

ABSTRACT: Although Trachemys scripta elegans is an exotic species popular as a pet in Brazil, studies on reproductive biology and capacity are non-existent in the Brazilian Cerrado. This study analyzed ovarian and oviduct characteristics and the egg production capacity of T. scripta elegans grown in this biome. The findings will associate with the size of the specimens and the sexual maturity, aiming at comparisons with native and exotic populations, as well as interspecific and contributing to the understanding of its impact on the invaded ecosystems and the establishment of eradication programs. Thus, 39 females had evaluated the body biometry and the morphology and morphometry of the ovaries and oviducts. G2 (N=20): with Class I (>5-10mm) follicles, with Class I and Class II (>10-fold) follicles, 25mm) and G3 (N=9) with Class I, Class II and Class III (>25mm) follicles. Analysis of variance, Scott-Knott’s test, and Pearson’s correlation analysis showed that there was no significant difference between the groups in body biometry; in the mean gonadosomatic index and gonadal morphometry, only the width of the oviducts in the right antimer and the mass and width in the left antimer were higher in G3, the only one that presented eggs. There was positive and harmonic development between body mass, carapace, and plastron, and gonadal growth occurred concomitantly with body growth, indicating a higher reproductive potential and a positive relationship between the size of the litter and the female litter. The gonadosomatic index proved to be an excellent reproductive indicator, and the ovarian evaluation was a better indicator of sexual maturity than the maximum carapace length. Ovaries were irregular structures, without delimitation between the cortical and medullary regions and filled with vitelogenic follicles of different diameters, atresic follicles, and corpora lutea, which reflected the ovarian complexity of the species and the presence of follicular hierarchy. In the scarce stroma, two germinative beds were observed per ovary and the presence of gaps very close to the follicles and associated with the blood vessels. Analysis of gonadal tissue revealed three types of oocytes according to cytoplasmic characteristics: homogeneous, vesicular or vesicular in the cortex with apparent granules. Oviducts were functional and separated, joining only in the final portion to form the cloaca and subdivided into infundibulum, tuba, isthmus, uterus, and vagina. The structure of the uterine tube was composed of serosa, muscular and mucous, which was full of glands. The presence of eggs in the oviducts indicated that the specimens can reproduce in the Brazilian Cerrado. This study provides necessary and relevant information on the reproductive biology and capacity of T. scripta elegans in the Brazilian Cerrado and can contribute to the understanding of its impact on the invaded ecosystems and the establishment of eradication programs. The extraction of females with capacity can reduce the annual reproductive yield of the species and decrease its effect on local biodiversity.

Drought leads to reproductive quiescence in smooth-billed anis: Phenotypic evidence for opportunistic breeding and reproductive readiness

Previous studies have suggested that the smooth-billed ani (Crotophaga ani, Linnaeus, 1758) breeds opportunistically following unpredictable rainfall in drought areas. To obtain proof of this phenomenon, the present study described and compared reproductive morphology and cell proliferation in the gonads of free-living smooth-billed anis during a wet season (April to June 2012) and the following dry season (July to September 2012) in a semiarid area using light and electron microscopy (transmission and scanning) and the AgNOR method. The morphological findings indicated distinct levels of reproductive activity related to seasonal changes. Morphological and morphometric analyses of the gonads confirmed intense gametogenic activity during the wet season, whereas gonadal involution occurred after rainfall ceased. The sizes of the testes and ovaries were significantly reduced compared to those in the wet season. The volumetric fraction of the seminiferous tubules in the testis decreased considerably, and no preovulatory follicles were detected in the ovary in the dry season. Moreover, the AgNOR count in the gonads revealed a significant decline in cell recruitment for gametogenesis after rainfall ceased. The histological findings indicated partial gonadal activation throughout the dry season. The analysis of the seminiferous epithelium confirmed the early testicular recrudescence phase, and sporadic postovulatory follicles indicated random ovulation during this time. The excurrent ducts and the oviduct also underwent remarkable involution in the dry season. Taken together, these findings confirm opportunistic breeding by smooth-billed anis in a semiarid habitat and suggest that gonadal recrudescence has been established as a reproductive strategy to cope with unexpected precipitation events.

Photoperiodic control of testicular growth, histomorphology and serum testosterone levels in the male Eurasian tree sparrow: involvement of circadian rhythm

Experiments were performed on the subtropical population of male Eurasian tree sparrow (Passer montanus) to examine the mediation of the circadian rhythms in photoperiodic regulation of reproductive responses. In the first experiment, photosensitive sparrows were exposed to different resonance light dark cycles viz. 6L/6D, 6L/18D, 6L/30D, 6L/42D, 6L/54D and 6L/66D along with a control group under long day length (14L/10D) for 35days. The birds read the cycles of 6L/6D, 6L/30D and 6L/54D as long day and exhibited significant testicular growth and increased testosterone levels while the cycles of 6L/18D, 6L/42D and 6L/66D were read as short day with no testicular response. In the second experiment, groups of photosensitive birds were subjected to various intermittent light dark cycles of 2L/2D, 3L/3D, 4L/4D, 6L/6D, 8L/8D and 12L/12D with two control groups kept under 9L/15D and 14L/10D for 35days. The birds held under the light/dark cycles of 2L/2D, 3L/3D, 4L/4D, 6L/6D and 12L/12D showed testicular growth and increased serum levels of testosterone while those exposed to 8L/8D did not. The responses were significantly higher in the birds exposed to 2L/2D, 3L/3D, 4L/4D and 6L/6D when compared to 12L/12D. Histomorphology of testes revealed different stages of spermatogenesis only under gonadostimulatory light regimes. The germinative epithelium thickness and diameter of seminiferous tubules increase while the thickness of testicular wall and area of interstitial space decrease with the increase in testicular volume. The above results indicate the involvement of an endogenous circadian rhythm in photoperiodic induction of testicular growth and functions.

Environmental control of seasonal reproduction in the wild and captive Eurasian Tree Sparrow (Passer montanus) with respect to variations in gonadal mass, histology, and sex steroids

The present study was undertaken on both sexes of the subtropical Eurasian Tree Sparrow (Passer montanus (L., 1758)) to investigate seasonal cycles of gonadal mass, histology, and hormones in relation to various environmental factors at Shillong, India. Attempts were also made to examine whether seasonal responses differ under wild and captivity and also between the sexes. Finally, reproductive seasonality of the sparrow under subtropical conditions was compared with the patterns found elsewhere in its distribution. Both sexes of the Tree Sparrow possess annual cycles of gonadal mass, histology, and steroids that follow the annual solar cycle. Increasing day length during spring stimulates gonadal growth with a corresponding increase in gonadal steroids followed by spontaneous gonadal regression leading to steroidal decline and photorefractoriness. Histomorphometric analyses of gonads revealed seasonal variations in the thickness of germinative epithelium and testicular wall, diameters of seminiferous tubules, and area of intertubular space in the males, and in the thickness of follicle wall and ratio of various follicles in the females. Although males responded in a similar fashion under wild and captivity, the responses of females deferred significantly. Thus, the Tree Sparrow exhibited sexual responses almost similar to their conspecifics at other latitudes.