Formation of reticulated endoderm, Reichert's membrane, and amniogenesis in blastocysts of captive-bred, short-tailed fruit bats,Carollia perspicillata

Abstract

Background and Methods As part of an effort to develop the short‐tailed fruit bat (Carollia perspicillata) as a new animal model for the study of interstitial implantation and trophoblast‐uterine interactions, early embryogenesis was examined histologically and ultrastructurally in captive‐bred females at different intervals after the first appearance of spermatozoa in daily vaginal smears (day 1 postcoitum [p.c.]). Results In most of the early uterine embryos examined on days 16‐18 p.c., much of the endoderm appeared as a reticulated meshwork; however, a unilocular yolk sac was formed prior to the development of any mesoderm. Early blastocysts of Carollia were also unusual in that endoderm surrounded much of the inner cell mass (ICM), Reichert's membrane continued over the dorsal side of the ICM, and basal laminalike material was observed around many of the endoderm and epiblast cells. A primordial amniotic cavity was formed between days 19 and 26 p.c. by cavitation. The first mesoderm appeared between days 23 and 26 p.c., concommitant with the development of an embryonic shield. Conclusion The unusual reticulated appearance of early endoderm in Carollia, which is reminiscent of that seen in early human blastocysts, may be attributable to constraints imposed on growth of the blastocyst by the site and mode of implantation, temporary retardation of trophoblastic invasion by the basal laminae of endometrial epithelial elements, and endodermal proliferation in anticipation of rapid yolk sac expansion. Reichert's membrane appears to play an important role in this species in tethering the ICM and embryonic shield to the developing placenta prior to the formation of significant amounts of mesoderm. Anat. Rec. 247:85‐101 © 1997 Wiley‐Liss, Inc.

Co-expression of cytokeratins and vimentin by highly invasive trophoblast in the white-winged vampire bat, Diaemus youngi, and the black mastiff bat, Molossus ater, with observations on intermediate filament proteins in the decidua and intraplacental trophoblast

“…One female carried a blastocyst (2.30 mm 2.82 mm) in which amniogenesis had been initiated. As in related species, this occurs by cavitation (Rasweiler, 1974;Rasweiler and Badwaik, 1996;Badwaik et al, 1997). Many of the myometrial vessels beneath the placenta had a single layer of highly invasive trophoblast immediately adjacent to the endothelial lining.…”

Ovulation, Fertilization, and Early Embryonic Development in the Menstruating Fruit Bat, Carollia perspicillata

“…It is apparent from studies of many early pregnant Carollia sp. that it takes about 13–14 days for CLs to develop to their full secretory appearance typical of the peri‐implantation period (Rasweiler and de Bonilla, 1992; Badwaik et al, 1997, unpublished observations). It therefore seems likely that all of the regressing CLs observed in this study had been formed by spontaneous ovulation before the introduction of the males.…”

“…These include (1) a temporal overlapping of folliculogenesis, as well as preparation of the oviduct for fertilization and maintenance of the early embryo, with uterine regression, (2) a cycle in which most endometrial regrowth is postovulatory, and (3) holding the embryo in the oviduct for an unusually long time (until at least 11–12 days p.c. in the case of C. perspicillata ) and to an advanced state of development (the expanded, zona‐free blastocyst stage) during endometrial regeneration (Badwaik et al, 1997; Badwaik and Rasweiler, 2000; Oliveira et al 2000; Rasweiler and Badwaik, 2000).…”

Morphological Variation of Primary Reproductive Structures in Males of Five Families of Neotropical Bats

“…Although most emphasis has been to the temperate species, which are subject to abrupt changes in temperature, the results observed for tropical species, has been very interesting. The most studies in tropical species generally deal with aspects of female reproduction and pregnancy (Rasweiler, 1972, 1974, 1978, 1982, 1987, 1993; Quintero and Rasweiler, 1974; Badwaik et al, 1997; Rasweiler and Badwaik, 1997; Badwaik and Rasweiler, 2001; Komar et al, 2007; Nolte et al, 2009), and only a few examinations are focused on male patterns, and these are primarily based in ecological–behavioral perspectives (Wilson and Findley, 1971; Fabián and Marques, 1989; Heideman et al, 1992; Heideman and Bronson, 1994; Zortéa, 2003; Léon‐Galván et al, 2005; Chaverri and Kunz, 2006; Costa et al, 2007; Ortêncio‐Filho et al, 2007).…”