Aspects of the histology of reproduction in the female Angolan free-tailed bat Mops condylurus (Microchiroptera: Molossidae) in Mpumalanga, South Africa

Abstract

The reproductive pattern of the female Angolan free-tailed bat Mops condylurus (A. Smith, 1933) was investigated at two localities in Mpumalanga. Female Angolan free-tailed bats displayed a seasonal bimodally polyoestrous reproductive pattern. Parturition in December was followed closely by a post-partum oestrus. Ovarian follicle and endometrium cycles also closely followed the breeding season. The reproductive tract displayed complete dextral dominance with the right ovary and uterus being functionally dominant. Luteal activity was maintained throughout pregnancy and healthy corpora lutea were observed until late in pregnancy. Shedding of the zona pellucida occurred in the oviduct in the region of the ampulla–isthmus junction. The embryo entered the uterus as a morula, where it was transformed into a unilaminar, free-lying blastocyst. A unique feature of the pre-implantation uterus was the formation of a distinct decidua at the implantation site on the mesometrial side. Implantation in the Angolan free-tailed bat was centric and superficial. First attachment of the trophoblast to the endometrium was mesometrial. The formation of a pre-placental pad of trophoblast cells was also initiated on the mesometrial side, while orientation of the embryonic disc was anti-mesometrial. Placental development occurred in the abembryonic hemisphere. Proliferation of the trophoblast over the embryonic hemisphere was slow and a bilaminar arrangement of the trophoblast was not observed in this region until after the primitive streak stage.