Preimplantation development, fate of the zona pellucida, and observations on the glycogen‐rich oviduct of the little bulldog bat, Noctilio albiventris

Abstract

The reproductive biology of Noctilio albiventris was investigated histologically in 112 females collected at the start of their synchronized breeding season during two different sampling years in the Cauca Valley of Colombia. Both ovaries were functional, but the animals were generally observed to be monovular. Embryonic development in the oviduct was found to proceed to blastocyst formation and loss of the zona pellucida. In 22 animals the discarded zona had been left behind in the oviduct upon passage of the embryo into the uterus and was still undissolved at the time of amniogenesis, the latest stage examined. The zonae which had passed into the uterus with the embryos often exhibited signs of dissolution. Most of the early blastocyts were morphologically distinctive, lacking a typical inner cell mass and being instead largely bilaminar. Degenerating ova from previous ovulations were found in the oviducts of two pregnant bats, suggesting that Noctilio may be another species in which the embryo stimulates its own escape from the oviduct. During tubal passage of the embryo the secretory cells of the oviductal ampulla and isthmus exhibited a transient engorgement with glycogen, particularly on the side ipsilateral to the new corpus luteum.

Enigmas of mammalian gamete form and function

“…Moreover, the physical character of the cumulus can vary -this being a dense mass with little or no extracellular matrix in some cases, and a matrix-rich short-lived structure in others (Section V.6). Thus the challenge apparently presented to spermatozoa by the short-lived diffuse cumulus in some artiodactyls (Crozet, Theron & Chenine, 1987) and noctilionoid bats (Rasweiler, 1977), may be very different from that in moles and hedgehogs, which have little matrix, and more so that in certain vespertilionid bats and Soricidae which appear to have none. In addition, it is possible that species differences in sperm head morphology, for example between that of Nesomys audeberti ( Fig.…”

“…For example, the cumulus persists for up to 10 h or so after ovulation in the rat and mouse, but for only an hour or so in some artiodactyls (Crozet et al, 1987), and this can display considerable diversity within a single order. Among Chiroptera, for instance, it undergoes extreme mucification in Noctilio albiventris, the little bulldog bat (Rasweiler, 1977), and in a long-winged bat, Miniopterus scheibersii, whereas the often long-lived follicle in many vespertilionids is occupied by a large dense mass of cells that does not mucify, and remains as such during fertilisation (T. Mōri, personal communication). Furthermore, the inference from such as the rat that the cumulus evolved primarily as a sperm-trapping device is complicated by finding that it has an essential role at fertilisation in the Chinese hamster Cricetulus griceus and shrews (and perhaps other Insectivora).…”

Sperm fertility and skewed paternity during sperm competition in the Australian long-eared bat Nyctophilus geoffroyi (Chiroptera: Vespertilionidae)

“…Prolonged storage of sperm is rare among mammals (Birkhead & Mùller, 1993a) but widespread among bats, particularly vespertilionid species, inhabiting temperate latitudes (Racey, 1979(Racey, , 1982. Prolonged sperm storage is typically found in conjunction with an ability to enter torpor (Racey, 1979;Krutzsch & Crichton, 1991; but see Rasweiler, 1977;and Chappell & Roverund, 1990), and, assuming stored sperm are fertile, one advantage of storing sperm when compared with other forms of reproductive delay (such as delayed development or implantation) may be the promotion of sperm competition (Birkhead & Mùller, 1993a).…”

Morphological study of changes in the baboon oviductal epithelium during the menstrual cycle

“…An interesting hypothesis about the function of such glycogen deposits is that of Rasweiler (1977; see also for references) who postulated that in the bat glycogen plays a critical role in maintaining the spermatozoa and the zygote at which time very large accumulations of glycogen are present.…”