Morphometric study of Rynchotus rufescens testis throughout the year

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.

Aspects of spermatogenesis and microscopic testicular morphology in Greater Rhea, Rhea americana (Linnaeus, 1758)

ABSTRACT: The purpose of this study was to study the microscopic morphology of the testicular parenchyma of Rhea americana birds. Fifty-four 2.5±0.5 year-old male adults bred in captivity. were used. During commercial slaughter, samples of testis were collected in November/2005, December/2006 and May/2007, in order to compare possible differences. The samples underwent optical microscopy analysis and measurements of seminiferous tubule (ST) total diameters, lumen, epithelium thickness and the relative volume of parenchyma. The ST had circular form in transverse cross sections. November/2005 and December/2006 samples had many types of germinative cells and spermatozoa in lumen, but in May/2007 the samples of epithelium were poor regarding meiotic and mitotic pictures, and it was difficult to find any spermatozoon; in many tubules the lumen was inexistent or diminished. In December/2006 and May/2007 the averages were: tubule diameter 110.3 and 5.3mμ, lumen 52.4 and 4.5mμ, epithelium thickness 57.8 and 0.7mμ respectively. The volumetric proportions were: seminiferous epithelium 75.6 and 75.9, cysts in epithelium 2.1 and 1.0, ST 93.3 and 84.0, interstitium 6.2 and 15.6 respectively. The sperm reserves were: 19.7±2 and 0±0 x109 sperm cells in December 2006 and May 2007 respectively. Microscopic measures of seminiferous tubules, spermatic cells and diameter of the nuclei were presented. These data confirm reproductive seasonality, with breeding season in spring-summer with sperm production. A great variation n parenchyma, when compared breeding was noticeable.

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.

Breed and seasonal variations in the testicular morphometry, gonadal and extragonadal sperm reserves of the barred plymouth rock and Nigerian indigenous breeds of the domestic fowl

Breed and seasonal influence on testicular morphometry, Gonadal Sperm Reserves (GSR), Extragonadal Sperm Reserves (ESR) was investigated in the barred Plymouth rock and the Nigerian indigenous breeds of the domestic fowl. Twenty sexually matured birds per breed were studied in the four seasons of the year. Breed significantly (p<0.01) influenced the body weight (2.11 +/- 0.05 vs. 1.58 +/- 0.02), paired testes weight (21.92 +/- 1.46 vs. 12.43 +/- 0.91) and all other morphometric parameters with the barred Plymouth Rock showing superiority over the Nigerian indigenous breed. The GSR, ESR and their efficiencies (GSR/g, ESR/g) were highly and significantly (p<0.01) higher in the barred Plymouth rock. Season neither significantly (P>0.05) influenced the testicular morphometric parameters, GSR, ESR nor gonadal sperm reserve/gram testis (GSR/g). The higher numerical differences observed in morphometric parameters, GSR and ESR during the early and late dry seasons suggested that the dry season favors sperm production, hence sperm reserve potentials. The testicular weight was significantly (p<0.001) correlated not only to the body weight (r = 0.63) but to paired Tunica albuginea (= 0.98, p<0.001) and paired epididymal weight (r = 0.69, p<0.001). There was also a significant (p<0.001) and positive correlation between the testicular weight and GSR (r = 0.84, p<0.001). The GSR/g (r = 0.77; p<0.001) ESR (r = 0.86; p<0.001) and ESR/g (r = 0.50, p<0.001). Based on these observations it is concluded that genetic improvement of the Nigerian indigenous breed of the domestic fowl can be carried out by increasing their body weight, hence, testicular weight through crossbreeding with the heavier barred Plymouth rock to achieve improved sperm production and reserve for year round artificial insemination.

Histological and morphometric analyses of seasonal testicular variations in the Jungle Crow (Corvus macrorhynchos)

A histological and morphometric study was conducted to examine the seasonal testicular variations in the Jungle Crow (Corvus macrorhynchos) of the Kanto area, Japan, from January to July. The paired testes mass, diameter and number of germ cells of the seminiferous tubules, and proportion of seminiferous tubule area and interstitium were examined. Hematoxylin and eosin-stained testis sections and ImageJ Software were used. Paired testes weight was found to increase by 55-fold from January to late March-early May, thereafter declining by 18-fold by June-July. Seminiferous tubule diameter increased fivefold from January to late March-early May, followed a fourfold decrease in June-July. The increase in testes weight correlated well with the increase in the diameter of the seminiferous tubule. In January, the seminiferous tubules constituted 56% of the testicular tissue and the interstitium 44%. During late March-early May, there was very little testicular interstitium (7.9%), and the seminiferous tubules were significantly enlarged (P < 0.05) (92%); this was followed by a gradual increase in the interstitial regression of testes. In January, the seminiferous epithelium contained a single layer of spermatogonia and Sertoli cells. The number of spermatogonia, primary and secondary spermatocytes, spermatids, and maturing spermatozoa were significantly increased (P < 0.05) in late March-early May, followed by regression from mid May. Our results indicate that the Jungle Crow has a non-breeding season in January, a pre-breeding season during February-mid March, a main breeding season during late March-early May, a transition period during mid May-late May, and a post-breeding season beginning in June.