The Neotropical bat species Artibeus planirostris and Eptesicus furinalis present a different morphology of the female reproductive organs: the first presents a simplex uterus, while the second presents a bicornuate uterus, but there is no information about their ovaries. Our aim was to compare the general ovary morphology and the folliculogenesis process in these species to increase the knowledge about the reproductive diversity of tropical bats. We observed a morphological distinction between the ovaries of both species: A. planirostris presents the primordial follicles located in a cranial portion of the ovary and the interstitial gland cells are not distinctive, while in E. furinalis, the primordial follicles are located throughout the cortex, and there is an abundance of interstitial gland cells. Both species present binovular or triovular follicles. Artibeus planirostris is a monovular species, with a preferential ovulation in the left side. Some females of E. furinalis exhibited two corpora lutea in the same ovary, and others presented a corpus luteum in both right and left ovaries at the same time; thus, E. furinalis is a polyovular species. Our results express the variation between two Neotropical species, reflecting the great variation in the reproductive aspects in Chiroptera.

Among species of the Chiroptera, spermatogenesis and the fully differentiated spermatozoa differ in morphological and ultrastructural detail. This study therefore aimed to ultrastructurally characterize the spermatogenesis and the spermatozoa of Carollia perspicillata (Phyllostomidae) and compare the process with other species of bats and mammals. The differentiation of spermatogonia is similar to other bats and to Primates, with three main spermatogonia types: Ad, Ap, and B. Meiotic divisions proceed similarly to those of most mammals and spermiogenesis is clearly divided into 12 steps, in the middle of the range of developmental steps for bats (9-16 steps). The process of acrosome formation is similar to that found in Platyrrhinus lineatus, with the acrosome formed by two different types of proacrosomal vesicles. The ultrastructure of the spermatozoon is similar to other bats already described and resembles the typical mammalian sperm model; however, its morphology differs from other mammals such as marsupials and rodents, on account of a simpler spermatozoon head morphology, which indicates a pattern that is more closely related to the sperm cells of humans and other primates. Our data demonstrated that spermatogenesis in C. perspicillata presents great ultrastructural similarities to P. lineatus. This pattern is not surprising, because both species belong to the same family (Phyllostomidae); however, it is observed that C. perspicillata presents some characteristics that are more closely related to phylogenetically distant species, such as Myotis nigricans (Vespertilionidae), which is a fact that deserves attention.