A comparative study of prenatal development in Miniopterus schreibersii fuliginosus, Hipposideros armiger and H. pratti

Abstract

Background: Bats comprise the second largest order of mammals. However, there are far fewer morphological studies of post-implantation embryonic development than early embryonic development in bats.

Results: We studied three species of bats (Miniopterus schreibersii fuliginosus, Hipposideros armiger and H. pratti), representing the two suborders Yangochiroptera and Yinpterochiroptera. Using an established embryonic staging system, we identified the embryonic stages for M. schreibersii fuliginosus, H. armiger and H. pratti and described the morphological changes in each species, including the development of the complex and distinctive nose-leaves in H. armiger and H. pratti. Finally, we compared embryonic and fetal morphology of the three species in the present study with five other species for which information is available.

Conclusion: As a whole, the organogenetic sequence of bat embryos is uniform and the embryos appear homoplastic before Stage 16. Morphological differentiation between species occurs mainly after embryonic Stage 16. Our study provides three new bat species for interspecific comparison of post-implantation embryonic development within the order Chiroptera and detailed data on the development of nose-leaves for bats in the superfamily Rhinolophoidea.

Figure 1

Phylogeny of the eight species of bats studied for embryogenesis. Species studied in this paper are underlined. Yinptero-, Yinpterochiroptera.

Figure 2

M. schreibersii fuliginosus at embryonic Stages 13-17. (A1-6) Stage 13. (B1-6) Stage 14. (C1-6) Stage 15. (D1-6) Stage 16. (E1-6) Stage 17. (A1, B1, C1, D1, E1) Lateral view with dorsal to the right; (A2, B2, C2, D2, E2) Ventral view; (A3, B3, C3, D3, E3) Dorsal view of the head and trunk; (A4, B4, C4, D4, E4) Dorsal view of the trunk and tail; (A5, B5, C5, D5, E5) Close-up for the left forelimb; (A6, B6, C6, D6, E6) Close-up for the left hindlimb. aer, apical ectodermal ridge; ah, auditory hillocks; cvf, cervical flexure; chp, chiropatagium; eam, external auditory meatus; eb, elbow; flb, forelimb bud; hlb, hindlimb bud; kn, knee; lv, lens vesicle; np, nasal pit; og, oral groove; plp, plagiopatagium; pi, pinna; pr, pigmented retina; prp, propatagium; tb, tail bud; tg, tragus; urp, uropatagium. Bar = 1 mm in A4, B4, C4, D4 and E4 (applies to A1-4, B1-4, C1-4, D1-4, E1-4); bar = 200 μm in A5-6, B5-6, C5-6, D5-6 and E5-6.

Figure 3

Craniofacial development of M. schreibersii fuliginosus, H. armiger and H. pratti. (A1-10) M. schreibersii fuliginosus: (A1) Lateral view of left side of Stage 13 head; (A2-10) Face-on views of Stage 14 (A2), Stage 15 (A3), Stage 16 (A4), Stage 17 (A5), Stage 18 (A6), Stage 20 (A7), Stage 23 (A8), fetal stage (A9), and adult (A10) heads. (B1-10) H. armiger: (B1) Lateral view of left side of Stage 11 head; (A2-9) Face-on views of Stage 14 (B2), Stage 17 (B3), Stage 18 (B4), Stage 19 (B5), Stage 20 (B6), Stage 22 (B7), fetal stage (B8), and adult (B9) heads; (B10) A diagram of an adult H. armiger's face illustrating nose-leaves. (C1-10) H. pratti: (C1) Lateral view of left side of Stage 11 head; (C2-9) Face-on views of Stage 14 (C2), Stage 15 (C3), Stage 16 (C4), Stage 19 (C5), Stage 20 (C6), Stage 22 (C7), fetal stage (C8), and adult (C9) heads; (C10) A diagram of an adult H. pratti's face illustrating nose-leaves. ah, auditory hillocks; at, antitragus; cc, chin cleft; el, eyelid; ep, eyelid primordium; fd, fold; ff, the 4th fold; fs, frontal sac; fsp, frontal sac primordium; ga, glossopharyngeal arch; ha, hyoid arch; hr, hair; lp, lens placode; lv, lens vesicle; md, mandible; mx, maxilla; ma, mandibular arch; mnl, main nose-leaf; nl, nose-leaf; nlp, nose-leaf primordium; np, nasal pit; nr, naris; og, oral groove; ope, optic evagination; opc, optic cup; otv, otic vesicle; pi, pinna; pig, pigment; pr, pigmented retina; pt, protuberance; sf, the second fold; sh, shield; tg, tragus; to, tongue; tp, tooth primordium; vf, vibrissal follicles. Bar = 200 μm in A1-5, B1-2 and C1-3; bar = 1 mm in A6-9, B3-8 and C4-8; bar = 2 mm in A10, B9 and C9.

Figure 4

Alcian blue staining. (A) M. schreibersii fuliginosus at Stage 15. (B) H. armiger at Stage 18 (limbs removed). Red arrows indicate the ribs and the triangle indicates the left hand plate with digit condensation. Bar = 1 mm.

Figure 5

M. schreibersii fuliginosus at embryonic Stages 18-23, the fetal stage and a newborn M. schreibersii fuliginosus. (A1-A6) Stage 18. (B1-B6) Stage 20. (C1-C6) Stage 23. (D1-D6) fetal stage. (E1-E6) newborn. (A1, B1, C1, D1, E1) Lateral view with dorsal to the right; (A2, B2, C2, D2, E2) Ventral view; (A3, B3, C3, D3, E3) Dorsal view of the head and trunk; (A4, B4, C4, D4, E4) Dorsal view of the trunk and tail; (A5, B5, C5, D5, E5) Close-up for the left forelimb; (A6, B6, C6, D6, E6) Close-up for the left hindlimb. a, autopod; cc, calcar; cl, claw; cp, claw primordium; s, stylopod; tm, thumb; tt, tooth; urp, uropatagium; z, zeugopod. Bar = 1 mm in A4, B4, C4, D4, E4 (applies to A1-4, B1-4, C1-4, D1-4, E1-4), A5-6, B5-6, C5-6, D5-6 and E5-6.

Figure 6

H. armiger at embryonic Stages 10-18. (A) Dorsal view of a five-somite embryo at Stage 10. (B) Dorsal view of a twelve-somite embryo at Stage 10. (C1-4) Stage 11. (D1-6) Stage 14. (E1-6) Stage 17. (F1-6) Stage 18. (C1, D1, E1, F1) Lateral view with dorsal to the right; (C2, D2, E2, F2) Ventral view; (C3, D3, E3, F3) Dorsal view of the head and trunk; (C4, D4, E4, F4) Dorsal view of the trunk and tail; (D5, E5, F5) Close-up for the left forelimb; (D6, E6, F6) Close-up for the left hindlimb. al, allantois; cc, calcar; chp, chiropatagium; crf, cranial flexure; cvf, cervical flexure; h, heart; hp, head process; nf, neural fold; np, nasal pit; nt, neural tube; plp, plagiopatagium; pr, pigmented retina; prp, propatagium; so, somite; tm, thumb; urp, uropatagium. Bar = 1 mm in B, C4, D4, E4, F4 (applies to C1-4, D1-4, E1-4, F1-4), E5-6 and F5-6; bar = 500 μm in A and D5-6.

Figure 7

H. armiger at embryonic Stages 19-23 and the fetal stage. (A1-A6) Stage 19. (B1-B6) Stage 22. (C1-C6) Stage 23. (D1-D6) fetal stage. (A1, B1, C1, D1) Lateral view with dorsal to the right; (A2, B2, C2, D2) Ventral view; (A3, B3, C3, D3) Dorsal view of the head and trunk; (A4, B4, C4, D4) Dorsal view of the trunk and tail; (A5, B5, C5, D5) Close-up for the left forelimb; (A6, B6, C6, D6) Close-up for the left hindlimb. a, autopod; cl, claw; cp, claw primordium; s, stylopod; z, zeugopod. Bar = 1 mm in A4, B4, C4, D4 (applies to A1-4, B1-4, C1-4, D1-4), A5-6, B5-6, C5-6 and D5-6.

Figure 8

H. pratti at embryonic Stages 11-22. (A1-4) Stage 11. (B1-6) Stage 14. (C1-6) Stage 15. (D1-6) Stage 16. (E1-6) Stage 22. (A1, B1, C1, D1, E1) Lateral view with dorsal to the right; (A2, B2, C2, D2, E2) Ventral view; (A3, B3, C3, D3, E3) Dorsal view of the head and trunk; (A4, B4, C4, D4, E4) Dorsal view of the trunk and tail; (B5, C5, D5, E5) Close-up for the left forelimb; (B6, C6, D6, E6) Close-up for the left hindlimb. ah, auditory hillocks; al, allantois; crf, cranial flexure; cvf, cervical flexure; eam, external auditory meatus; h, heart; lv, lens vesicle; np, nasal pit; plp, plagiopatagium; pr, pigmented retina; prp, propatagium. Bar = 1 mm in A4, B4, C4, D4, E4 (applies to A1-4, B1-4, C1-4, D1-4, E1-4), D5-6 and E5-6; bar = 500 μm in B5-6 and C5-6.