Evaluation of the uterine hormonal control of the bat Artibeus lituratus during the different phases of its reproductive cycle.

Artibeus lituratus is a frugivorous bat that directly assists in the restoration of degraded habitats through the effective dispersion of seeds and fruits. Given its great importance, this work aimed to evaluate the uterine hormonal control of A. lituratus during its different reproductive phases. The uteri of 30 sexually mature adult females, five specimens for each of the six sample groups (NON, nonreproductive; P1, initial pregnancy; P2, intermediate pregnancy; P3, advanced pregnancy; LAC, lactating; P + LAC, pregnant-lactating), were submitted to analyses of serum estradiol and progesterone concentrations, in addition to immunohistochemical analyses. Both estradiol and progesterone, gradually increased during pregnancy, with a marked significant increase in P3 females. Both returned to low levels in LAC-females; however, estradiol levels decreased further in P + LAC-females, while progesterone increased in the same group. In general, signs indicative of aromatase expression were observed in the endometrium of all analyzed groups and in the placenta of bats in the gestation groups. Similarly, ERα and PR were expressed in the myometrium, endometrium and placenta at varying levels of intensity. The results indicate that the uterine microenvironment of A. lituratus is directly regulated by serum concentrations of estradiol and progesterone, and fluctuations in these concentrations control morphological and physiological changes of this organ during different phases of the reproductive cycle. RESEARCH HIGHLIGHTS: Increases in serum concentrations of estradiol and progesterone coordinate the gestational period of A. lituratus. Estradiol activates ERα, stimulating cell proliferation in the uterus, in addition to activating the expression of PR, which trigger the quiescence of the myometrium and stimulation of the secretion and differentiation of the endometrium. Results showed several similarities to humans, indicating the use of A. lituratus as an animal model in reproductive studies.

Morphological analysis of the male reproductive accessory glands of the bat Artibeus lituratus (Phyllostomidae: Chiroptera).

Bats are distributed worldwide from tropical to temperate regions. Despite their wide geographical radiation and advances in studies using evolutionary approaches, aspects related to the reproduction of these animals remain poorly explored, especially those related to the male reproductive accessory glands (RAGs). Thus, the aim of this study was to analyze the morphophysiology of the male RAGs in the bat Artibeus lituratus. The RAGs in A. lituratus are composed of a compact intra-abdominal glandular complex, consisting of the prostate with two prostatic regions (ventral and dorsal), plus Littre glands and a pair of extra-abdominal bulbourethral glands. The ventral region of the prostate has an epithelium with variable morphology, due to its holocrine type of secretion. In contrast, the dorsal region has a typical cubic-to-columnar pseudostratified epithelium. Both regions contain two cell types, basal and secretory cells. Similar to the epithelial morphology, the secretion also varies, with the ventral region containing numerous PAS-positive globular vesicles, whereas the dorsal region has a more fluid, hyaline and PAS-negative secretion. Littre glands are dispersed in the connective tissue of the urethra, while the bulbourethral glands are located in the penile root, both glands with cubic-to-columnar pseudostratified epithelium and globular PAS-positive secretion. The results demonstrate that the RAGs of A. lituratus are composed of two prostatic regions, ventral and dorsal, and urethral and bulbourethral glands, with no seminal vesicles. Each prostatic region has unique and distinctive characteristics, with the ventral region presenting an exclusive holocrine nature and the dorsal region having similarities to the ventral prostate of rodents.