Inner Ear Morphology in the Atlantic Molly Poecilia mexicana—First Detailed Microanatomical Study of the Inner Ear of a Cyprinodontiform Species
Figure 4
Relationship of the depth of the sulcus acusticus, thickness of the otolithic membrane, and curvature of the macula sacculi.
Light micrographs of transversal semithin-sections (thickness: 1 µm) displaying the difference of the thickness of the otolithic membrane between cave (A, B) and surface fish (C, D). (A), cave fish female (SL = 51 mm), (B), cave fish male (SL = 37 mm), (C), surface fish from Río Oxolotán (female, SL = 44 mm), and (D), surface fish from Tampico (female, SL = 30 mm). (B1–D1), sections of the rostral part of the right macula sacculi not overlain by the sagitta. Black arrowheads indicate a dorsal swelling of the basal lamina flanking the macula which is distinctly developed in cave fish and in surface fish from Río Oxolotán. (A, B2–D2), sections in the central region of the sulcus acusticus as indicated by the black dashed line in (B3). (B3–D3) show the medial face of the left otoliths of the same individuals of which the sections in (B1–D1) and (B2–D2) are presented. 1*, upper ‘compact’ part of the otolithic membrane; 2*, lower part of the otolithic membrane displaying numerous pores. BL, basal lamina; OM, otolithic membrane; SE, sensory epithelium (macula sacculi); VIII, part of the eighth cranial nerve. Sections were stained with Richardson's solution. Scale bars = 100 µm.