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Figure 1 | Frontiers in Zoology

Figure 1

From: Evolution of clitellate phaosomes from rhabdomeric photoreceptor cells of polychaetes – a study in the leech Helobdella robusta (Annelida, Sedentaria, Clitellata)

Figure 1

H. robusta TX; TEM observations of pigmented eyes (A-C) and extraocular PRCs (D-E). A. Low power micrograph showing half of a cross section, pigmented eyes are made up of several phaosomal PRCs (asterisk) surrounded by a thin layer of pigmented supporting cells (psc). Eyes embedded in the connective tissue below the epidermis. B. The PRCs of the eye and the PSCs are separated by ECM (ecm, arrows), PRCs (prc) are closely apposed. C. Border between two adjacent PRCs (arrow); note densely arranged sensory microvilli (smv) and mitochondria (m). D. Low power micrograph showing half of a cross section anterior to the eyes; extraocular phaosomal PRCs (boxed) dispersed along the anterior head margin. E. Extraocular phaosome, sensory microvilli fill the entire phaosomal cavity (phc). The nucleus (n) is at one edge of the PRC (prc) forming the phaosomal cavity. Note ECM separating two adjacent PRCs (arrows). Detail of D. F. Enlargement of sensory microvilli (smv) cut in various directions. Note dense filamentous core in each microvillus. - asterisks: pigmented eyes; bv blood vessel; ecm ECM; m mitochondrion; mo mouth opening; n nucleus; phc phaosomal cavity; prc photoreceptor cell; psc pigmented supportive cell; smv sensory microvilli.

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