A review on the morphology of ovarian follicles in Elasmobranchs: a case study in Rhizoprionodon taylori

SIMPFENDORFER, C.; AWRUCH C. A.; WALTRICK, D.

JOURNAL OF MORPHOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2017 vol. 278 p. 486 - 499

0362-2525

The identification of the elasmobranch secondaryovarian follicles and their function can be challengingand the inconsistent use of terminology derived fromother taxa is a matter of ongoing debate. In this study, theavailable information on the histology of the elasmobranchsecondary ovarian follicles derived from atresia (preovulatoryfollicles) or ovulation (postovulatory follicles) isreviewed highlighting their morphology and steroidogeniccapacity. Based on this literature review, the ovarian folliclesof the Australian sharpnose shark Rhizoprionodontaylori were classified according to their preovulatory orpostovulatory origin. Two types of secondary follicles originatingfrom atresia of developing follicles (atretic previtellogenicfollicles) and ripe follicles (atretic vitellogenicfollicles), and one type of postovulatory follicle were identifiedthroughout the reproductive year of this species.Morphological similarities of the elasmobranch secondaryovarian follicles and their variations in different speciesdenote the difficulty to classify them. Given the multipleorigins of ovarian follicles, their poorly understood functionsand capacity to supply steroids, visual identificationof these structures and the use of terminology derivedfrom mammalian and other vertebrate studies (with theexception of the corpora lutea as a temporary endocrinegland) is not advisable.