Reproductive biology of the female leaf-nosed bat, Macrotus californicus, in Southwestern United States: I. a morphometric analysis of the annual ovarian cycle.
In Macrotus californicus (Phyllostomatidae), normal embryogenesis(March-June) is preceded by a period of delayed development (October- March) characterized by implantation and slow growth of the embryo to the primitive streak stage. The events of the annual reproductive cycle can be correlated with ovarian dynamics. Waves of follicular growth appear to be initiated in January and June. Increased multilaminar follicles resulting from the second wave of recruitment appear from August to October. Vesiculation of these follicles is seen in both ovaries from July to January; however, the single Graafian follicle forms only in the right ovary just prior to ovulation in late October-early November. Left ovarian ovulation can be induced by right ovariectomy. High atresia from July to December may retard embryo genesis by failing to provide an optimal hormone milieu for the conceptus. In addition, luteal cells are small during the initial months of embryonic development.The first wave of follicular growth results in the appearance of an increased percentage of growing follicles in April; resultant enhanced estrogen levels may influence the resumption of normal development, an event which also coincides with luteal cell hypertrophy. It would appear possible, therefore,that delayed development in Macrotus is an expression of luteal cell insufficiency and uterine nutritional incompetence resulting from depressed steroid levels. Termination of delay may be brought about by the action of increased levels of estrogen and/or progesterone on the endometrium, perhaps by influencing the activity of mast cells whose products are known in some species to enhance vascularity which in turn could account for added substances essential to normal fetal growth.
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D000818:Animals; D002685:Chiroptera; D004958:Estradiol; D005260:Female; D005640:Follicle Stimulating Hormone; D006801:Humans; D008597:Menstrual Cycle; D006080:Ovarian Follicle; D010053:Ovary; D010060:Ovulation; D011374:Progesterone; D015206:Southwestern United States
D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone