Zebrafish Anatomical Dictionary

Structure description: sensory patches of the ear

by Tanya Whitfield

Name: sensory patches of the ear

Abbreviation: : am, pm, anterior and posterior maculae; ac, lc, pc, anterior, lateral and posterior cristae

Synonyms: anterior macula, posterior macula (also known as the posteromedial macula), cristae

Figures:

4 day ear Sensory patches bmp4/msx expression

Dissected ears Anterior macula polarities Lateral crista polarities Posterior macula polarities

Description: Patches of thickened, pseudostratified epithelium of the inner ear, consisting of regular arrays of sensory hair cells interspersed with supporting cells. Each patch has its own charcteristic shape and polarity pattern. The anterior macula is rounded. At 5 days of development, the hair cell polarity pattern of the anterior macula resembles that of the adult utricle (Platt, 1993), with most hair cells radiating out laterally from a medial point, and a rim of hair cells around the lateral edge of the macula pointing medially. The day 5 posterior macula has a rounded posterior section and a slim anterior projection. At this stage, in the anterior projection, hair cells are arranged in an antiparallel fashion, while in the posterior region of the macula, hair cells point away from a midline separating dorsal and ventral halves. This is the "standard" four-quadrant pattern for a teleost sacculus (Popper et al., 1982), but the adult zebrafish sacculus has been described to have a "vertical" pattern, i.e. lacking the anterior region of antiparallel organisation (Platt, 1993). The anterior and posterior cristae are saddle shaped; the lateral crista, at day 4 and 5, is triangular, with a few hair cells separated from, and lying medial to, the apex of the triangle. Hair cells within a crista all point in the same direction.

Homologues:

• Human: sensory patches of the inner ear
• Mouse: sensory patches of the inner ear
• Chicken: sensory patches of the inner ear
• Frog: sensory patches of the inner ear
• Fly: none

Stages:

• First appears at: 24h (differentiated ear hair cells; the decision to become sensory epithelium probably occurs at a much earlier stage)
• Disappears (or changes name) at: Unknown

Parents (forms from): cranial placodal ectoderm (otic placode)

Children:

• Presumptive (thought to give rise to): The anterior macula of the larva corresponds to the utricular macula of the adult; the posterior macula probably forms the saccular macula. The origins of the lagena and macula neglecta of the adult are unknown.
• Anlage (known to give rise to): Unknown

Group (member of):

• Anatomical (group member): Ear
• Functional (group member): Mechanosensory systems

Markers:

• mRNA:
  
  bmp2b, bmp4, bmp7 (Chin et al., 1997; Dick et al., 2000; Lee et al., 1998; Martinez-Barberá et al., 1997)
  deltaA, deltaB, deltaD, serrateB (Haddon et al., 1998)
  eya1 (Sahly et al., 1999)
  msxc, msxd (Ekker et al., 1997; Ekker et al., 1992)


• Antibodies:
  
  Pax2a (Riley et al., 1999
  S100 zn1, zn5, zn15, zns2


• Other: None

Publications:

• Primary: Haddon, C., and Lewis, J. (1996). Early ear development in the embryo of the zebrafish, Danio rerio. Journal of Comparative Neurology 365, 113-123.
• Secondary:
  

  Chin, A. J., Chen, J.-N., and Weinberg, E. S. (1997). Bone morphogenetic protein-4 expression characterizes inductive boundaries in organs of developing zebrafish. Development, Genes and Evolution 207, 107-114..

  Dick, A., Hild, M., Bauer, H., Imai, Y., Maifeld, H., Schier, A. F., Talbot, W. S., Bouwmeester, T., and Hammerschmidt, M. (2000). Essential role of Bmp7 (snailhouse) and its prodomain in dorsoventral patterning of the zebrafish embryo. Development 127, 343-354

  Ekker, M., Akimenko, M.-A., Bremiller, R., and Westerfield, M. (1992). Regional expression of three homeobox transcripts in the inner ear of zebrafish embryos. Neuron 9, 27-35.

  Haddon, C., Jiang, Y.-J., Smithers, L., and Lewis, J. (1998). Delta-Notch signalling and the patterning of sensory cell differentiation in the zebrafish ear: Evidence from the mindbomb mutant. Development 125, 4637-4644.

  Lee, K.-H., Marden, J. J., Thompson, M. S., Maclennan, H., Kishimoto, Y., Pratt, S. J., Schulte-Merker, S., Hammerschmidt, M., Johnson, S. L., Postlethwait, J. H., Beier, D. C., and Zon, L. I. (1998). Cloning and genetic mapping of zebrafish BMP-2. Developmental Genetics 23, 97-103.

  Martinez-Barberá, J. P., Toresson, H., Da Rocha, S., and Krauss, S. (1997). Cloning and expression of three members of the zebrafish BMP family: Bmp2a, Bmp2b and Bmp4. Gene 198, 53-59

  Platt, C. (1993). Zebrafish inner ear sensory surfaces are similar to those in goldfish. Hearing Research 65, 133-140.

  Popper, A. N., Platt, C., and Saidel, W. M. (1982). Acoustic functions in the fish ear. Trends in Neurosciences 5, 276-280.

  Riley, B. B., Chiang, M.-Y., Farmer, L., and Heck, R. (1999). The deltaA gene of zebrafish mediates lateral inhibition of hair cells in the inner ear and is regulated by pax2.1. Development 126, 5669-5678..

  Sahly, I., Andermann, P., and Petit, C. (1999). The zebrafish eya1 gene and its expression pattern during embryogenesis. Development, Genes and Evolution 209, 399-410.

Comments: None